Use of the oral glucose tolerance test to assess insulin release and insulin sensitivity

Higher early pregnancy plasma myo-inositol associates with increased postprandial glycaemia later in pregnancy: Secondary analyses of the NiPPeR randomized controlled trial

AIM

Myo-inositol supplementation from ~13 weeks' gestation reportedly improves glycaemia regulation in metabolically at-risk women, with speculation that earlier supplementation might bring further improvement. However, the NiPPeR trial of a myo-inositol-containing supplement starting preconception did not lower gestational glycaemia in generally healthy women. We postulated that the earlier timing of supplementation influences the maternal metabolic adaptation for gestational glycaemia regulation.

METHODS

In total, 585 women were recruited from Singapore, UK and New Zealand for the NiPPeR study. We examined associations of plasma myo-inositol concentrations at 7 and 28 weeks' gestation with 28 weeks plasma glucose (PG; fasting, and 1 h and 2 h in 75 g oral glucose tolerance test) and insulin indices using linear regression adjusting for covariates.

RESULTS

Higher 7-week myo-inositol, but not 28-week myo-inositol, associated with higher 1 h PG [βadj (95% confidence intervals) 0.05 (0.01, 0.09) loge mmol/L per loge μmol/L, p = .022] and 2 h PG [0.08 (0.03, 0.12), p = .001]; equivalent to 0.39 mmol/L increase in 2 h PG for an average 7-week myo-inositol increase of 23.4 μmol/L with myo-inositol supplementation. Higher 7-week myo-inositol associated with a lower 28-week Stumvoll index (first phase), an approximation of insulin secretion [-0.08 (-0.15, -0.01), p = .020] but not with 28-week Matsuda insulin sensitivity index. However, the clinical significance of a 7-week myo-inositol-related increase in glycaemia was limited as there was no association with gestational diabetes risk, birthweight and cord C-peptide levels. In-silico modelling found higher 28-week myo-inositol was associated with lower gestational glycaemia in White, but not Asian, women after controlling for 7-week myo-inositol effects.

CONCLUSION

To our knowledge, our study provides the first evidence that increasing first trimester plasma myo-inositol may slightly exacerbate later pregnancy post-challenge glycaemia, indicating that the optimal timing for starting prenatal myo-inositol supplementation needs further investigation.

Metabolomic and genetic architecture of gestational diabetes subtypes

AIMS/HYPOTHESIS

Physiological gestational diabetes mellitus (GDM) subtypes that may confer different risks for adverse pregnancy outcomes have been defined. The aim of this study was to characterise the metabolome and genetic architecture of GDM subtypes to address the hypothesis that they differ between GDM subtypes.

METHODS

This was a cross-sectional study of participants in the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study who underwent an OGTT at approximately 28 weeks' gestation. GDM was defined retrospectively using International Association of Diabetes and Pregnancy Study Groups/WHO criteria, and classified as insulin-deficient GDM (insulin secretion <25th percentile with preserved insulin sensitivity) or insulin-resistant GDM (insulin sensitivity <25th percentile with preserved insulin secretion). Metabolomic analyses were performed on fasting and 1 h serum samples in 3463 individuals (576 with GDM). Genome-wide genotype data were obtained for 8067 individuals (1323 with GDM).

RESULTS

Regression analyses demonstrated striking differences between the metabolomes for insulin-deficient or insulin-resistant GDM compared to those with normal glucose tolerance. After adjustment for covariates, 33 fasting metabolites, including 22 medium- and long-chain acylcarnitines, were uniquely associated with insulin-deficient GDM; 23 metabolites, including the branched-chain amino acids and their metabolites, were uniquely associated with insulin-resistant GDM; two metabolites (glycerol and 2-hydroxybutyrate) were associated with the same direction of association with both subtypes. Subtype differences were also observed 1 h after a glucose load. In genome-wide association studies, variants within MTNR1B (rs10830963, p=3.43×10-18, OR 1.55) and GCKR (rs1260326, p=5.17×10-13, OR 1.43) were associated with GDM. Variants in GCKR (rs1260326, p=1.36×10-13, OR 1.60) and MTNR1B (rs10830963, p=1.22×10-9, OR 1.49) demonstrated genome-wide significant association with insulin-resistant GDM; there were no significant associations with insulin-deficient GDM. The lead SNP in GCKR, rs1260326, was associated with the levels of eight of the 25 fasting metabolites that were associated with insulin-resistant GDM and ten of 41 1 h metabolites that were associated with insulin-resistant GDM.

CONCLUSIONS/INTERPRETATION

This study demonstrates that physiological GDM subtypes differ in their metabolome and genetic architecture. These findings require replication in additional cohorts, but suggest that these differences may contribute to subtype-related adverse pregnancy outcomes.

Atypical Diabetes: What Have We Learned and What Does the Future Hold?

As our understanding of the pathophysiology of diabetes evolves, we increasingly recognize that many patients may have a form of diabetes that does not neatly fit with a diagnosis of either type 1 or type 2 diabetes. The discovery and description of these forms of "atypical diabetes" have led to major contributions to our collective understanding of the basic biology that drives insulin secretion, insulin resistance, and islet autoimmunity. These discoveries now pave the way to a better classification of diabetes based on distinct endotypes. In this review, we highlight the key biological and clinical insights that can be gained from studying known forms of atypical diabetes. Additionally, we provide a framework for identification of patients with atypical diabetes based on their clinical, metabolic, and molecular features. Helpful clinical and genetic resources for evaluating patients suspected of having atypical diabetes are provided. Therefore, appreciating the various endotypes associated with atypical diabetes will enhance diagnostic accuracy and facilitate targeted treatment decisions.

Clinical and Metabolic Characterization of Women With Gestational Diabetes Mellitus Within the First Year Postpartum

Context

Women with gestational diabetes mellitus (GDM) have an increased risk of long-term complications, including impaired glucose metabolism, type 2 diabetes (T2DM), cardiovascular disease, and obesity. In current clinical practice, a 1 size fits all approach to GDM is applied, although heterogeneity among women with GDM has been recognized.

Objective

To give the most adequate preventive care and postpartum (PP) guidance, we aimed to make a metabolic characterization and identify subgroups of women with previous GDM within the first year PP.

Methods

In this prospective cohort study, we collected data in gestational week 34-38, at 3 months, and 1 year PP on women with GDM who participated in a PP follow-up program in Central Region Denmark from April 2019 to December 2022.

Results

In total, 1270 women were included in the program in late pregnancy. Of the 768 women participating in either the oral glucose tolerance test 3 months PP (n = 545) or the 1-year follow-up (n = 493) or both (n = 261), 608 (79.2%) were normoglycemic, 137 (17.8%) had prediabetes, 20 (2.6%) had T2DM, and 3 (.4%) had developed T1DM. More than 40% of the women gained weight in the first year PP compared with their pregestational weight.

Conclusion

Our study shows that 20.8% of women with GDM who volunteered to participate in a clinical follow-up program developed prediabetes or diabetes (T1DM and T2DM) within the first year PP. The GDM diagnosis encompasses a heterogenetic group of women and a deeper characterization may provide an opportunity for a more personalized risk assessment to prevent the progression to T2DM.

Estimating insulin sensitivity and β-cell function from the oral glucose tolerance test: validation of a new insulin sensitivity and secretion (ISS) model

Efficient and accurate methods to estimate insulin sensitivity (SI) and β-cell function (BCF) are of great importance for studying the pathogenesis and treatment effectiveness of type 2 diabetes (T2D). Existing methods range in sensitivity, input data, and technical requirements. Oral glucose tolerance tests (OGTTs) are preferred because they are simpler and more physiological than intravenous methods. However, current analytical methods for OGTT-derived SI and BCF also range in complexity; the oral minimal models require mathematical expertise for deconvolution and fitting differential equations, and simple algebraic surrogate indices (e.g., Matsuda index, insulinogenic index) may produce unphysiological values. We developed a new insulin secretion and sensitivity (ISS) model for clinical research that provides precise and accurate estimates of SI and BCF from a standard OGTT, focusing on effectiveness, ease of implementation, and pragmatism. This model was developed by fitting a pair of differential equations to glucose and insulin without need of deconvolution or C-peptide data. This model is derived from a published model for longitudinal simulation of T2D progression that represents glucose-insulin homeostasis, including postchallenge suppression of hepatic glucose production and first- and second-phase insulin secretion. The ISS model was evaluated in three diverse cohorts across the lifespan. The new model had a strong correlation with gold-standard estimates from intravenous glucose tolerance tests and insulin clamps. The ISS model has broad applicability among diverse populations because it balances performance, fidelity, and complexity to provide a reliable phenotype of T2D risk.NEW & NOTEWORTHY The pathogenesis of type 2 diabetes (T2D) is determined by a balance between insulin sensitivity (SI) and β-cell function (BCF), which can be determined by gold standard direct measurements or estimated by fitting differential equation models to oral glucose tolerance tests (OGTTs). We propose and validate a new differential equation model that is simpler to use than current models and requires less data while maintaining good correlation and agreement with gold standards. Matlab and Python code is freely available.

Multiomics analysis revealed the mechanism of the anti-diabetic effect of Salecan

Salecan, a natural β-glucan compromising nine residues connected by β-(1 → 3)/α-(1 → 3) glycosidic bonds, is one of the newly approved food ingredients. Salecan has multiple health-improving effects, yet its mechanism against Type 2 diabetes mellitus (T2DM) remains poorly understood. In this study, the hypoglycemic effect and underlying mechanism of Salecan intervention on STZ-induced diabetic model mice were investigated. After 8 weeks of gavage, Salecan attenuated insulin resistance and repaired pancreatic β cells in a dose-dependent manner. In addition, Salecan supplement remodel the structure of the gut microbiota and altered the level of intestinal metabolites. Serum metabolites, especially unsaturated fatty acids, were also affected significantly. In addition, tight junction proteins in the colon and autophagy-related proteins in the pancreas were upregulated. Multiomics analysis indicated that Lactobacillus johnsonii, Muribaculaceae, and Lachnoclostridium were highly associated with fatty acid esters of hydroxy fatty acids (FAHFA) levels in the colon, accordingly enhancing arachidonic acid and linoleic acid in serum, and promoting GLP-1 release in the intestine and insulin secretion in the pancreas, thus relieving insulin resistance and exhibiting hypoglycemic effects. These findings provide a novel understanding of the anti-diabetic effect of Salecan in mice from a molecular perspective, paving the way for the wide use of Salecan.

Causal relationship between sleep apnea and non-alcoholic fatty liver disease: A Mendelian randomization study

BACKGROUND

Observational studies indicate that sleep apnea is associated with non-alcoholic fatty liver disease (NAFLD) and its related metabolic features, independent of confounding factors including obesity. However, the causal relationships remain to be determined.

METHODS

Univariable and multivariable Mendelian randomization (MR) analyses were performed to investigate the causal relationship between sleep apnea and NAFLD, along with its typical features including liver function, glycemic traits and lipid profiles. Summary-level data for sleep apnea were obtained from the Finngen consortium (33,423 cases and 307,648 controls). Summary-level data for NAFLD were available from a GWAS meta-analysis (8434 cases and 770,180 controls), and data for 12 NAFLD-related features from corresponding published GWASs. The inverse variance weighted (IVW) analysis was employed as the primary statistical method. Bidirectional MR and CAUSE analysis were conducted to avoid reverse causality and false positive findings.

RESULTS

In univariable MR analyses, we found evidence to support a causal effect of genetically predicted sleep apnea on NAFLD (OR = 1.50, 95% CI = 1.18-1.91) and HDL-C (β = -0.045, 95% CI = -0.090 to -0.001). In reverse MR, genetically predicted serum TG was associated with an increased risk of sleep apnea (OR = 1.07, 95% CI = 1.02-1.12), while genetically predicted HDL-C was associated with a decreased risk of sleep apnea (OR = 0.93, 95% CI = 0.89-0.98). After adjusting body mass index or educational attainment, none of these causal associations were retained. However, CAUSE method and MR analyses focusing on lipoprotein subfractions supported a causal effect of sleep apnea on HDL-C and HDL subfractions.

CONCLUSION

This MR study indicated that sleep apnea has no direct causal association with NAFLD, elevated liver enzymes and insulin resistance. Our results showed suggestive inverse associations of genetically predicted sleep apnea on HDL-C and HDL subfractions, indicating that both HDL-C levels and HDL function may be causally implicated in sleep apnea.

Evaluation of insulin secretion and insulin sensitivity in pregnant women: Application value of simple indices

The prevalence of gestational diabetes mellitus (GDM) is increasing annually, which poses substantial harm to the health of both mothers and children. Therefore, selection of clinically applicable and easily detectable indicators in the assessment of maternal insulin secretory function and insulin sensitivity in pregnant women undoubtedly holds great importance in evaluating the risk of GDM, guiding the choice of GDM therapy modalities, and improving the ability to provide early warning of adverse pregnancy outcomes. Compared with the classic clamp technique, many simple indices are more suited for use among pregnant women due to the low frequency of blood sampling and simple administration involved. While indices derived from fasting blood glucose and fasting insulin levels are most readily available, they are unable to provide information on the ability of insulin to manage the glucose load during pregnancy. Although the indices derived from the insulin and glucose values at each time point of the oral glucose tolerance test can provide a more comprehensive picture of the insulin sensitivity and insulin secretory function of the body, their application is constrained by the complexity of the procedure and associated high costs. Concomitantly, the findings from different studies are influenced by a variety of confounding factors, such as the gestational age during testing, race, and detection method. Furthermore, insulin secretory function and insulin sensitivity in pregnant women differ from those in non-pregnant women in that they change significantly with prolonged pregnancy; hence, there is an urgent need to develop a pregnancy-specific reference range. This article reviews the progress in the application of simple indices to help clinicians better understand their potential application in detecting GDM.

Mediation effect of serum zinc on insulin secretion inhibited by methyl tert-butyl ether in gas station workers

Methyl tert-butyl ether (MTBE), a type of gasoline additive, has been found to affect insulin function and glucose homeostasis in animal experiments, but there is still no epidemiological evidence. Zinc (Zn) is a key regulatory element of insulin secretion and function, and Zn homeostasis can be disrupted by MTBE exposure through inducing oxidative stress. Therefore, we suspected that Zn might be involved and play an important role in the process of insulin secretion inhibited by MTBE exposure. In this study, we recruited 201 male subjects including occupational and non-occupational MTBE exposure from Anhui Province, China in 2019. Serum insulin and functional analog fibroblast growth factor 1 (FGF1) and blood MTBE were detected by Elisa and headspace solid-phase microextraction and gas chromatography-high-resolution mass spectrometry. According to MTBE internal exposure level, the workers were divided into low- and high-exposed groups and found that the serum insulin level in the high-exposed group was significantly lower than that in the low-exposed group (p = 0.003) while fasting plasma glucose (FPG) level increased obviously in the high-exposed group compared to the low-exposed group (p = 0.001). Further analysis showed that MTBE exposure level was positively correlated with FPG level, but negatively correlated with serum insulin level, which suggested that the FPG level increase might be related to the decrease of serum insulin level induced by MTBE exposure. The results of further mediation effect analysis showed that changes in serum zinc levels played a major intermediary role in the process of insulin secretion inhibition and blood glucose elevation caused by MTBE exposure. In addition, a significant negative correlation was found between MTBE exposure and serum Zn level, which might play a strong mediating effect on the inhibition of insulin secretion induced by MTBE exposure. In conclusion, our study provided evidence that MTBE could inhibit insulin secretion and interfere with Zn metabolism in gas station workers for the first time, and found that Zn might play an important mediation effect during the process of inhibiting insulin secretion and interfering with glucose metabolism induced by MTBE exposure.

The supplementation of the multi-strain probiotics WHHPRO™ alleviates high-fat diet-induced metabolic symptoms in rats via gut-liver axis

Metabolic syndrome (MS) has emerged as one of the major global health concerns, accompanied by a series of related complications, such as obesity and type-2 diabetes. The gut-liver axis (GLA) is a bidirectional communication between the gut and the liver. The GLA alterations have been revealed to be closely associated with the development of MS. Probiotics within Lactobacillus and Bifidobacterium confer beneficial effects on improving MS symptoms. WHHPRO™ is a mixture of four probiotic strains, with potential MS-improving abilities. This study aimed to investigate the effects of WHHPRO™ on MS symptoms using a high-fat diet (HFD) rat model. Oral administration of WHHPRO™ for 12 weeks improved glucose tolerance, blood lipid, body weight, and liver index in HFD rats. WHHPRO™ shaped the gut microbiome composition by increasing the abundance of Lactobacillus and Akkermansia and normalized the reduced SCFA levels in HFD rats. Besides, WHHPRO™ modulated the fecal bile acids (BAs) profile, with decreased levels of T-b-MCA and 12-KDCA and increased levels of LCA and ILCA. Meanwhile, WHHPRO™ increased total unconjugated BAs in feces and liver and reduced the accumulation of total hepatic BA pool size in HFD rats. Moreover, WHHPRO™ reversed the expression of genes associated with impaired BA metabolism signaling in the ileum and liver. Our findings suggest that WHHPRO™ exerted beneficial effects on improving MS symptoms, involving the modulation of the gut microbiome composition, SCFAs, and the FXR-FGF15 signaling along the GLA. Supplementation of WHHPRO™ may serve as a novel strategy for improving MS symptoms.

Effects of Consuming Beverages Sweetened with Fructose, Glucose, High-Fructose Corn Syrup, Sucrose, or Aspartame on OGTT-Derived Indices of Insulin Sensitivity in Young Adults

(1) Background: Clinical results on the effects of excess sugar consumption on insulin sensitivity are conflicting, possibly due to differences in sugar type and the insulin sensitivity index (ISI) assessed. Therefore, we compared the effects of consuming four different sugars on insulin sensitivity indices derived from oral glucose tolerance tests (OGTT). (2) Methods: Young adults consumed fructose-, glucose-, high-fructose corn syrup (HFCS)-, sucrose-, or aspartame-sweetened beverages (SB) for 2 weeks. Participants underwent OGTT before and at the end of the intervention. Fasting glucose and insulin, Homeostatic Model Assessment-Insulin Resistance (HOMA-IR), glucose and insulin area under the curve, Surrogate Hepatic Insulin Resistance Index, Matsuda ISI, Predicted M ISI, and Stumvoll Index were assessed. Outcomes were analyzed to determine: (1) effects of the five SB; (2) effects of the proportions of fructose and glucose in all SB. (3) Results: Fructose-SB and the fructose component in mixed sugars negatively affected outcomes that assess hepatic insulin sensitivity, while glucose did not. The effects of glucose-SB and the glucose component in mixed sugar on muscle insulin sensitivity were more negative than those of fructose. (4) Conclusion: the effects of consuming sugar-SB on insulin sensitivity varied depending on type of sugar and ISI index because outcomes assessing hepatic insulin sensitivity were negatively affected by fructose, and outcomes assessing muscle insulin sensitivity were more negatively affected by glucose.

Bridging the Gap: Pancreas Tissue Slices From Organ and Tissue Donors for the Study of Diabetes Pathogenesis

Over the last two decades, increased availability of human pancreatic tissues has allowed for major expansions in our understanding of islet biology in health and disease. Indeed, studies of fixed and frozen pancreatic tissues, as well as efforts using viable isolated islets obtained from organ donors, have provided significant insights toward our understanding of diabetes. However, the procedures associated with islet isolation result in distressed cells that have been removed from any surrounding influence. The pancreas tissue slice technology was developed as an in situ approach to overcome certain limitations associated with studies on isolated islets or fixed tissue. In this Perspective, we discuss the value of this novel platform and review how pancreas tissue slices, within a short time, have been integrated in numerous studies of rodent and human islet research. We show that pancreas tissue slices allow for investigations in a less perturbed organ tissue environment, ranging from cellular processes, over peri-islet modulations, to tissue interactions. Finally, we discuss the considerations and limitations of this technology in its future applications. We believe the pancreas tissue slices will help bridge the gap between studies on isolated islets and cells to the systemic conditions by providing new insight into physiological and pathophysiological processes at the organ level.

ARTICLE HIGHLIGHTS

Human pancreas tissue slices represent a novel platform to study human islet biology in close to physiological conditions. Complementary to established technologies, such as isolated islets, single cells, and histological sections, pancreas tissue slices help bridge our understanding of islet physiology and pathophysiology from single cell to intact organ. Diverse sources of viable human pancreas tissue, each with distinct characteristics to be considered, are available to use in tissue slices for the study of diabetes pathogenesis.

Lysophosphatidylinositols Are Upregulated After Human β-Cell Loss and Potentiate Insulin Release

In this study, we identified new lipid species associated with the loss of pancreatic β-cells triggering diabetes. We performed lipidomics measurements on serum from prediabetic mice lacking β-cell prohibitin-2 (a model of monogenic diabetes) patients without previous history of diabetes but scheduled for pancreaticoduodenectomy resulting in the acute reduction of their β-cell mass (∼50%), and patients with type 2 diabetes (T2D). We found lysophosphatidylinositols (lysoPIs) were the main circulating lipid species altered in prediabetic mice. The changes were confirmed in the patients with acute reduction of their β-cell mass and in those with T2D. Increased lysoPIs significantly correlated with HbA1c (reflecting glycemic control), fasting glycemia, and disposition index, and did not correlate with insulin resistance or obesity in human patients with T2D. INS-1E β-cells as well as pancreatic islets isolated from nondiabetic mice and human donors exposed to exogenous lysoPIs showed potentiated glucose-stimulated and basal insulin secretion. Finally, addition of exogenous lysoPIs partially rescued impaired glucose-stimulated insulin secretion in islets from mice and humans in the diabetic state. Overall, lysoPIs appear to be lipid species upregulated in the prediabetic stage associated with the loss of β-cells and that support the secretory function of the remaining β-cells.

ARTICLE HIGHLIGHTS

Circulating lysophosphatidylinositols (lysoPIs) are increased in situations associated with β-cell loss in mice and humans such as (pre-)diabetes, and hemipancreatectomy. Pancreatic islets isolated from nondiabetic mice and human donors, as well as INS-1E β-cells, exposed to exogenous lysoPIs exhibited potentiated glucose-stimulated and basal insulin secretion. Addition of exogenous lysoPIs partially rescued impaired glucose-stimulated insulin secretion in islets from mice and humans in the diabetic state. LysoPIs appear as lipid species being upregulated already in the prediabetic stage associated with the loss of β-cells and supporting the function of the remaining β-cells.

Are postprandial glucose responses sufficiently person-specific to use in personalized dietary advice? Design of the RepEAT study: a fully controlled dietary intervention to determine the variation in glucose responses

Introduction

An elevated postprandial glucose response is associated with an increased risk of cardiometabolic diseases. Existing research suggests large heterogeneity in the postprandial glucose responses to identical meals and food products between individuals, but the effect of other consumed meals during the day and the order of meals during the day on the heterogeneity in postprandial glucose responses still needs to be investigated. In addition, the robustness of the glucose responses to meals or foods is still unknown.

Objectives

The overall aim of the project is to assess whether the glucose response to a meal is sufficiently person-specific to use in personalized dietary advice. We aim to answer the question: "How replicable are glucose responses to meals within individuals and how consistent is the variation in glucose responses between individuals?"

Methods

The question will be assessed under standardized conditions of a 9-week fully controlled dietary intervention in which all meals are the same between individuals and consumed in a fixed order at a fixed time. 63 apparently healthy men and women with a BMI of 25-40 kg/m2 and aged 45-75 years were enrolled in the RepEAT study (NCT05456815), of whom 53 participants completed the study. The RepEAT study comprised a fully controlled dietary intervention of nine weeks, consisting of three repetitive periods of three weeks. Within each three-week period, a variety of meals and food products were offered during breakfast, lunch, dinner and in between meal snacks. Throughout the dietary intervention, glucose was continuously monitored using Freestyle Libre Pro IQ monitors. Physical activity was monitored using the ActiGraph and ActivPAL. To measure the association between glucose responses and an individual's phenotype, various measurements were performed before the start of the dietary intervention including an oral glucose tolerance test, a high-fat mixed meal challenge, assessment of body fat distribution including liver fat (MRI/MRS), and cardiometabolic markers.

Discussion

The repetitive and fully controlled nature of the dietary study allows detailed assessment of the replicability of the glucose responses to meals and food products within individuals. Furthermore, the consistency of the variation between individuals independent of insulin resistance will be determined.

Pregnancy glucagon-like peptide 1 predicts insulin but not glucose concentrations

AIMS

Incretin hormones glucagon-like peptide 1 (GLP-1) and gastric inhibitory peptide (GIP) cause increased insulin secretion in non-pregnant adults, but their role in pregnancy, where there are additional metabolically-active hormones from the placenta, is less clear. The aim of the present study was to assess if fasting and post-load incretin concentrations were predictive of pregnancy insulin and glucose concentrations.

METHODS

Pregnant women (n = 394) with one or more risk factors for gestational diabetes were recruited at 28 weeks for a 75 g oral glucose tolerance test (OGTT). Glucose, insulin, GLP-1 and GIP were measured in the fasting state and 120 min after glucose ingestion.

RESULTS

Fasting plasma GLP-1 concentrations were associated with plasma insulin (standardised β' 0.393 (0.289-0.498), p = 1.3 × 10-12; n = 306), but not with glucose concentrations (p = 0.3). The association with insulin was still evident when adjusting for BMI (β' 0.271 (0.180-0.362), p = 1.1 × 10-8; n = 297). Likewise, at 120 min the OGTT GLP-1 concentrations were associated with plasma insulin concentrations (β' 0.216 (0.100-0.331), p  = 2.7 × 10-4; n = 306) even after adjusting for BMI (β' 0.178 (0.061-0.294), p = 2.9 × 10-3; n = 296), but not with glucose (p  = 0.9). GIP concentrations were not associated with insulin or glucose concentrations at either time point (all p  > 0.2). In pregnancy plasma GLP-1, but not GIP, concentrations appear to be predictive of circulating insulin concentrations, independently of associations with BMIs.

CONCLUSIONS

These results suggest that the relationship between insulin and incretins is preserved in pregnancy, but that other factors, such as placental hormones or counter-regulatory hormones, may be more important determinants of glycaemia and gestational diabetes aetiology.

Distinct Insulin Physiology Trajectories in Euglycemic Pregnancy and Gestational Diabetes Mellitus

OBJECTIVE

To evaluate changes in insulin physiology in euglycemic pregnancy and gestational diabetes mellitus (GDM).

RESEARCH DESIGN AND METHODS

Participants underwent oral glucose tolerance tests at ≤15 weeks' gestation (early pregnancy), 24-32 weeks' gestation (mid-late pregnancy), and 6-24 weeks postpartum. We evaluated longitudinal changes in insulin secretory response (log Stumvoll first-phase estimate) and insulin sensitivity (log Matsuda index) using linear mixed models. We then evaluated participants who met GDM criteria in early pregnancy (early GDM) and mid-late pregnancy (classic GDM) separately from those without GDM. We derived the pregnancy insulin physiology (PIP) index to quantify β-cell compensation for insulin resistance.

RESULTS

Among 166 participants, 21 had early GDM and 24 developed classic GDM. Insulin sensitivity was reduced slightly in early pregnancy (β = -0.20, P < 0.001) and substantially in mid-late pregnancy (β = -0.47, P < 0.001) compared with postpartum. Insulin secretory response (adjusted for insulin sensitivity) was augmented in early pregnancy (β = 0.16, P < 0.001) and mid-late pregnancy (β = 0.16, P = 0.001) compared with postpartum. Compared with postpartum, the PIP index was augmented in early pregnancy (β = 215, P = 0.04) but not mid-late pregnancy (β = 55, P = 0.64). Early GDM was distinguished by a substantial reduction in early pregnancy insulin sensitivity (β = -0.59, P < 0.001) compared with postpartum. Both early and classic GDM lacked evidence of early pregnancy augmentation of insulin secretory response (adjusted for insulin sensitivity) and the PIP index (P > 0.1 vs. postpartum). Early pregnancy PIP index predicted GDM independent of participant characteristics (area under the curve without PIP index 0.70 [95% CI 0.61-0.79], area under the curve with PIP index 0.87 [95% CI 0.80-0.93]).

CONCLUSIONS

β-Cell function is enhanced in early pregnancy. Deficient first-trimester β-cell function predicts GDM.

Effects of an Unripe Avocado Extract on Glycaemic Control in Individuals with Obesity: A Double-Blinded, Parallel, Randomised Clinical Trial

BACKGROUND

Unripe avocados (Persea americana) are naturally enriched in mannoheptulose (MH), which is a candidate caloric restriction mimetic.

OBJECTIVES

To evaluate the effects of a diet supplement made from unripe avocado on glucose tolerance, and cardiometabolic risk factors in free-living nondiabetic adults with obesity.

METHODS

In a double-blinded, randomised controlled trial, 60 adults (female n = 47, age 48 ± 13 years, BMI 34.0 ± 2.6 kg/m2) were stratified by sex and randomised to avocado extract (AvX, 10 g finely ground, freeze-dried unripe avocado) or placebo (10 g finely ground cornmeal plus 5% spinach powder) daily, for 12 weeks. The primary outcome was a change in glucose area under the curve (AUC) in response to a 75 g oral glucose tolerance test. A post-hoc analysis was subsequently performed in a subgroup with insulin AUC above the median of baseline values after removal of participants >2 SD from the mean.

RESULTS

There were no between-group differences in glucose AUC (p = 0.678), insulin AUC (p = 0.091), or cardiovascular outcomes. In the subgroup analysis, insulin AUC was lower in AxV versus placebo (p = 0.024).

CONCLUSIONS

Daily consumption of unripe avocado extract enriched in MH did not alter glucose tolerance or insulin sensitivity in nondiabetic adults with obesity, but the data provided preliminary evidence for a benefit in insulin AUC in a subgroup of participants with elevated baseline postprandial insulin levels.

A Preoperative Nomogram for Prediction of Postoperative Hypocortisolism in Patients with Pituitary Adenomas: A Single-Center Retrospective Cohort Study

BACKGROUND

Patients with pituitary adenomas (PAs) are at an increased risk preoperatively and postoperatively for hypopituitarism. Postoperative hypocortisolism is associated with increased mortality and morbidity as well as poor quality of life. However, research about the risk factors for postoperative hypocortisolism is limited, and a predictive nomogram for postoperative hypocortisolism has not yet been developed. We aimed to investigate the predictive factors for postoperative hypocortisolism and construct a dynamic online nomogram.

METHODS

Our database included 438 consecutive PA patients who were hospitalized and treated with transsphenoidal surgery by experienced neurosurgeons from the different medical teams in the Neurosurgery Department, Jinling Hospital, between January 2018 and October 2020. The final study group included 238 eligible patients. Data on possible predictors, including age, sex, treatment history of PAs, preoperative signs and symptoms, primary recurrence subtype, and clinical subtypes, were collected. Univariable and multivariable logistic regression analyses were applied to identify independent predictors, which were included in constructing the nomogram model. The calibration curve and receiver operating characteristic curve were computed to evaluate the predictive performance of the nomogram model.

RESULTS

The incidence of postoperative hypocortisolism was 12.08%. Three preoperative predictors were identified to construct the nomogram: surgical type (microscopic or endoscopic, with endoscopic surgery proven to be the protective factor) (odds ratio, 0.24; 95% confidence interval [CI], 0.093-0.610; P = 0.003), prothrombin time (odds ratio, 2.40; 95% CI, 1.332-4.326; P = 0.004), and basophil cell count (odds ratio, 5.25; 95% CI, 1.270-21.816; P = 0.022,). The area under the curve of receiver operating characteristic curve for the constructed nomogram was 0.749 (95% CI, 0.640-0.763); a well-fixed calibration curve was generated for the nomogram model. An interactive web-based dynamic nomogram application was also constructed.

CONCLUSIONS

In this study, surgical type, prothrombin time, and basophil cell count were the most relevant predictive factors for postoperative hypocortisolism. A predictive nomogram that can preoperatively assess the risk of hypocortisolism after surgical treatment of PAs was developed. This nomogram could be helpful in identifying high-risk patients who require close monitoring of serum cortisol levels and initiating clinical procedures for patients requiring cortisol administration therapy as a lifesaving strategy.

Randomised controlled trial of preconception lifestyle intervention on maternal and offspring health in people with increased risk of gestational diabetes: study protocol for the BEFORE THE BEGINNING trial

INTRODUCTION

Gestational diabetes mellitus (GDM) is associated with increased risk for type 2 diabetes in the mother and cardiometabolic diseases in the child. The preconception period is an optimal window to adapt the lifestyle for improved outcomes for both mother and child. Our aim is to determine the effect of a lifestyle intervention, initiated before and continued throughout pregnancy, on maternal glucose tolerance and other maternal and infant cardiometabolic outcomes.

METHODS AND ANALYSIS

This ongoing randomised controlled trial has included 167 females aged 18-39 years old at increased risk for GDM who are contemplating pregnancy. The participants were randomly allocated 1:1 to an intervention or control group. The intervention consists of exercise (volume is set by a heart rate-based app and corresponds to ≥ 1 hour of weekly exercise at ≥ 80% of individual heart rate maximum), and time-restricted eating (≤ 10 hours/day window of energy intake). The primary outcome measure is glucose tolerance in gestational week 28. Maternal and offspring outcomes are measured before and during pregnancy, at delivery, and at 6-8 weeks post partum. Primary and secondary continuous outcome measures will be compared between groups based on the 'intention to treat' principle using linear mixed models.

ETHICS AND DISSEMINATION

The Regional Committees for Medical and Health Research Ethics in Norway has approved the study (REK 143756). The anonymised results will be submitted for publication and posted in a publicly accessible database of clinical study results.

TRIAL REGISTRATION NUMBER

Clinical trial gov NCT04585581.

Impact of saturated compared with unsaturated dietary fat on insulin sensitivity, pancreatic β-cell function and glucose tolerance: a systematic review and meta-analysis of randomized, controlled trials

BACKGROUND

The impact of the dietary fat type on type 2 diabetes (T2D) remains unclear.

OBJECTIVES

We aimed to evaluate the effects of replacing dietary saturated fatty acids (SFA) with mono- or poly-unsaturated fatty acids (MUFA and PUFA, respectively) on insulin sensitivity, pancreatic β-cell function, and glucose tolerance, as surrogate endpoints for T2D.

METHODS

We conducted a systematic review and meta-analysis of randomized controlled trials that replaced ≥5% of total energy intake provided by SFA with MUFA or PUFA and reported indexes of insulin sensitivity, β-cell function, and/or glucose tolerance. We searched MEDLINE, Scopus, and the Cochrane Library (CENTRAL) up to 9 January, 2023. Eligible interventions had to be isocaloric, with no significant difference in other macronutrients. Data were synthesized using random-effects model meta-analysis.

RESULTS

Of 6355 records identified, 10 parallel and 20 crossover trials with 1586 participants were included. The mean age of the participants was 42 years, 47% were male, mean body mass index (BMI; in kg/m2) was 26.8, median baseline fasting glucose was 5.13 mmol/L, and the median duration of interventions was 5 weeks. Replacing SFA with MUFA or PUFA had no significant effects on insulin sensitivity [standardized mean difference (SMD) SFA compared with MUFA: 0.01, 95% confidence interval (CI): -0.06 to 0.09, I2 = 0% and SMD SFA compared with PUFA: 0, 95% CI: -0.15 to 0.14, I2 = 0%]. Replacing SFA with MUFA did not significantly impact the β-cell function, evaluated by the disposition index (mean difference: -12, 95% CI: -158 to 133, I2=0%). Evidence on glucose tolerance (SFA compared with MUFA or PUFA) and on β-cell function when SFA were replaced with PUFA was scant.

CONCLUSIONS

Short-term substitution of saturated with unsaturated fat does not significantly affect insulin sensitivity nor β-cell function (the latter in the SFA compared with MUFA comparison). Future studies are needed to elucidate longer term effects of dietary fat saturation on glucose homeostasis. This trial was registered at PROSPERO as CRD42020178382.

Energy expenditure and intensity of ritual jumping-dancing in male Maasai

OBJECTIVES

Traditional jumping-dance rituals performed by Maasai men involve prolonged physical exertion that may contribute significantly to overall physical activity level. We aimed to objectively quantify the metabolic intensity of jumping-dance activity and assess associations with habitual physical activity and cardiorespiratory fitness (CRF).

METHODS

Twenty Maasai men (18-37 years) from rural Tanzania volunteered to participate in the study. Habitual physical activity was monitored using combined heart rate (HR) and movement sensing over 3 days, and jumping-dance engagement was self-reported. A 1-h jumping-dance session resembling a traditional ritual was organized, during which participants' vertical acceleration and HR were monitored. An incremental, submaximal 8-min step test was performed to calibrate HR to physical activity energy expenditure (PAEE) and assess CRF.

RESULTS

Mean (range) habitual PAEE was 60 (37-116) kJ day-1  kg-1 , and CRF was 43 (32-54) mL O2  min-1  kg-1 . The jumping-dance activity was performed at an absolute HR of 122 (83-169) beats·min-1 , and PAEE of 283 (84-484) J min-1  kg-1 or 42 (18-75)% when expressed relative to CRF. The total PAEE for the session was 17 (range 5-29) kJ kg-1 , ~28% of the daily total. Self-reported engagement in habitual jumping-dance frequency was 3.8 (1-7) sessions/week, with a total duration of 2.1 (0.5-6.0) h/session.

CONCLUSIONS

Intensity during traditional jumping-dance activity was moderate, but on average sevenfold higher than habitual physical activity. These rituals are common, and can make a substantial contribution to overall physical activity in Maasai men, and thus be promoted as a culture-specific activity to increase energy expenditure and maintain good health in this population.

Glucose Regulation after Partial Pancreatectomy: A Comparison of Pancreaticoduodenectomy and Distal Pancreatectomy in the Short and Long Term

BACKGRUOUND

Long term quality of life is becoming increasingly crucial as survival following partial pancreatectomy rises. The purpose of this study was to investigate the difference in glucose dysregulation after pancreaticoduodenectomy (PD) or distal pancreatectomy (DP).

METHODS

In this prospective observational study from 2015 to 2018, 224 patients who underwent partial pancreatectomy were selected: 152 (67.9%) received PD and 72 (32.1%) received DP. Comprehensive assessment for glucose regulation, including a 75 g oral glucose tolerance test was conducted preoperatively, and 1, 12, and 52 weeks after surgery. Patients were further monitored up to 3 years to investigate development of new-onset diabetes mellitus (NODM) in patients without diabetes mellitus (DM) at baseline or worsening of glucose regulation (≥1% increase in glycosylated hemoglobin [HbA1c]) in those with preexisting DM.

RESULTS

The disposition index, an integrated measure of β-cell function, decreased 1 week after surgery in both groups, but it increased more than baseline level in the PD group while its decreased level was maintained in the DP group, resulting in a between-group difference at the 1-year examination (P<0.001). During follow-up, the DP group showed higher incidence of NODM and worsening of glucose regulation than the PD group with hazard ratio (HR) 4.29 (95% confidence interval [CI], 1.49 to 12.3) and HR 2.15 (95% CI, 1.09 to 4.24), respectively, in the multivariate analysis including dynamic glycemic excursion profile. In the DP procedure, distal DP and spleen preservation were associated with better glucose regulation. DP had a stronger association with glucose dysregulation than PD.

CONCLUSION

Proactive surveillance of glucose dysregulation is advised, particularly for patients who receive DP.

Assessment of circulating insulin using liquid chromatography-mass spectrometry during insulin glargine treatment in type 2 diabetes: Implications for estimating insulin sensitivity and β-cell function

AIM

To determine the potential impact of the cross-reactivity of insulin glargine U-100 and its metabolites on insulin sensitivity and β-cell measures in people with type 2 diabetes.

MATERIALS AND METHODS

Using liquid chromatography-mass spectrometry (LC-MS), we measured concentrations of endogenous insulin, glargine and its two metabolites (M1 and M2) in fasting and oral glucose tolerance test-stimulated plasma from 19 participants and fasting specimens from another 97 participants 12 months after randomization to receive the insulin glargine. The last dose of glargine was administered before 10:00 PM the night before testing. Insulin was also measured on these specimens using an immunoassay. We used fasting specimens to calculate insulin sensitivity (Homeostatic Model Assessment 2 [HOMA2]-S%; QUICKI index; PREDIM index) and β-cell function (HOMA2-B%). Using specimens following glucose ingestion, we calculated insulin sensitivity (Matsuda ISI[comp] index) and β-cell response (insulinogenic index [IGI], and total incremental insulin response [iAUC] insulin/glucose).

RESULTS

In plasma, glargine was metabolized to form the M1 and M2 metabolites that were quantifiable by LC-MS; however, the analogue and its metabolites cross-reacted by less than 100% in the insulin immunoassay. This incomplete cross-reactivity resulted in a systematic bias of fasting-based measures. By contrast, because M1 and M2 did not change following glucose ingestion, a bias was not observed for IGI and iAUC insulin/glucose.

CONCLUSIONS

Despite glargine metabolites being detected in the insulin immunoassay, dynamic insulin responses can be used to assess β-cell responsiveness. However, given the cross-reactivity of the glargine metabolites in the insulin immunoassay, fasting-based measures of insulin sensitivity and β-cell function are biased.

Genome-wide association study and functional characterization identifies candidate genes for insulin-stimulated glucose uptake

Distinct tissue-specific mechanisms mediate insulin action in fasting and postprandial states. Previous genetic studies have largely focused on insulin resistance in the fasting state, where hepatic insulin action dominates. Here we studied genetic variants influencing insulin levels measured 2 h after a glucose challenge in >55,000 participants from three ancestry groups. We identified ten new loci (P < 5 × 10-8) not previously associated with postchallenge insulin resistance, eight of which were shown to share their genetic architecture with type 2 diabetes in colocalization analyses. We investigated candidate genes at a subset of associated loci in cultured cells and identified nine candidate genes newly implicated in the expression or trafficking of GLUT4, the key glucose transporter in postprandial glucose uptake in muscle and fat. By focusing on postprandial insulin resistance, we highlighted the mechanisms of action at type 2 diabetes loci that are not adequately captured by studies of fasting glycemic traits.

Exercise and Prediabetes After Renal Transplantation (EXPRED-I): A Prospective Study

BACKGROUND

Post-transplant diabetes mellitus (PTDM) beyond 12 months (late PTDM) is a severe complication after renal transplantation. Late PTDM develops mostly in subjects with prediabetes. Although exercise may have a potential role in preventing late PTDM, there are no previous data on the effect of exercise in patients with prediabetes.

MATERIAL AND METHODS

The design was a 12-month exploratory study to test the capacity of exercise in reverting prediabetes in order to prevent late-PTDM. The outcome was the reversibility of prediabetes, assessed every 3 months with oral glucose tolerance tests (OGTT). The protocol included an incremental plan of aerobic and/or strength training as well as an active plan for promoting adherence (telephone calls, digital technology, and visits). A priori, a sample size cannot be calculated which makes this an exploratory analysis. Based on previous studies, the spontaneous reversibility of prediabetes was 30% and the reversibility induced by exercise will account for another 30%, a total reversibility of 60% (p value < 0.05, assuming a potency of 85%). Ad interim analysis was performed during follow-up to test the certainty of this sample calculation. Patients beyond 12 months after renal transplantation with prediabetes were included.

RESULTS

The study was interrupted early due to efficacy after the evaluation of the follow-up of 27 patients. At the end of follow-up, 16 (60%) patients reverted to normal glucose levels at fasting (from 102.13 mg/dL ± 11 to 86.75 ± 6.9, p = 0.006) and at 120 min after the OGTTs (154.44 mg/dL ± 30 to 113.0 ± 13.1, p = 0.002) and 11 patients had persistent prediabetes (40%). Also, insulin sensitivity improved with the reversibility of prediabetes, compared to those with persistent prediabetes: 0.09 [0.08-0.11] versus 0.04 [0.01-0.07], p = 0.001 (Stumvoll index). Most needed at least one increment in the prescription of exercise and compliance. Finally, measures aimed at the improvement of compliance were successful in 22 (80%) patients.

CONCLUSION

Exercise training was effective to improve glucose metabolism in renal transplant patients with prediabetes. Exercise prescription must be conducted considering both the clinical characteristics of the patients and pre-defined strategy to promote adherence. The trial registration number of the study was NCT04489043.

Associations of alanine aminotransferase/aspartate aminotransferase with insulin resistance and β-cell function in women

We tested whether alanine aminotransferase/aspartate aminotransferase (ALT/AST), a marker of hepatosteatosis, associates with insulin resistance, β-cell function and postglucose glycemia. We studied 311 young and 148 middle-aged Japanese women, whose BMI averaged < 23.0 kg/m². Insulinogenic index and Matsuda index were evaluated in 110 young and 65 middle-aged women. In two groups of women, ALT/AST was associated positively with homeostasis model assessment insulin resistance (HOMA-IR) and inversely with Matsuda index. In middle-aged women only, the ratio was also associated positively with fasting and postload glycemia and HbA1c. The ratio showed negative association with disposition index (a product of insulinogenic index and Matsuda index). On multivariate linear regression analysis, HOMA-IR emerged as a single determinant of ALT/AST in young and middle-aged women (standardized β: 0.209, p = 0.003 and 0.372, p = 0.002, respectively). ALT/AST was associated with insulin resistance and β-cell function even in non-obese Japanese women, suggesting a pathophysiologic basis in its prediction of diabetic risk.

Ultrasound Stimulation Potentiates Management of Diabetic Hyperglycemia

OBJECTIVE

Glucose homeostasis is the only way to manage diabetic progression as all medications used do not cure diabetes. This study was aimed at verifying the feasibility of lowering glucose with non-invasive ultrasonic stimulation.

METHODS

The ultrasonic device was homemade and controlled via a mobile application on the smartphone. Diabetes was induced in Sprague-Dawley rats through high-fat diets followed by streptozotocin injection. The treated acupoint CV12 was at the middle of the xiphoid and umbilicus of the diabetic rats. Parameters of ultrasonic stimulation were an operating frequency of 1 MHz, pulse repetition frequency of 15 Hz, duty cycle of 10% and sonication time of 30 min for a single treatment.

DISCUSSION

The diabetic rats exhibited a significant decrease of 11.5% ± 3.6% in blood glucose in 5 min of ultrasonic stimulation (p < 0.001). After the single treatment on the first day, third day and fifth day in the first week, the treated diabetic rats had a significantly small area under the curve of the glucose tolerance test (p < 0.05) compared with the untreated diabetic rats in the sixth week. Hematological analyses indicated that the serum concentrations of β-endorphin were significantly increased by 58% ± 71.9% (p < 0.05) and the insulin level was increased by 56% ± 88.2% (p = 0.15) without statistical significance after a single treatment.

CONCLUSION

Therefore, non-invasive ultrasound stimulation at an appropriate dose can produce a hypoglycemic effect and improve glucose tolerance for glucose homeostasis and may play a role as adjuvant therapy with diabetic medications in the future.

The Glycemic Curve during the Oral Glucose Tolerance Test: Is It Only Indicative of Glycoregulation?

The shape of the glycemic curve during the oral glucose tolerance test (OGTT), interpreted in the correct context, can predict impaired glucose homeostasis. Our aim was to reveal information inherent in the 3 h glycemic trajectory that is of physiological relevance concerning the disruption of glycoregulation and complications beyond, such as components of metabolic syndrome (MS).

METHODS

In 1262 subjects (1035 women, 227 men) with a wide range of glucose tolerance, glycemic curves were categorized into four groups: monophasic, biphasic, triphasic, and multiphasic. The groups were then monitored in terms of anthropometry, biochemistry, and timing of the glycemic peak.

RESULTS

Most curves were monophasic (50%), then triphasic (28%), biphasic (17.5%), and multiphasic (4.5%). Men had more biphasic curves than women (33 vs. 14%, respectively), while women had more triphasic curves than men (30 vs. 19%, respectively) (p < 0.01). Monophasic curves were more frequent in people with impaired glucose regulation and MS compared to bi-, tri-, and multiphasic ones. Peak delay was the most common in monophasic curves, in which it was also most strongly associated with the deterioration of glucose tolerance and other components of MS.

CONCLUSION

The shape of the glycemic curve is gender dependent. A monophasic curve is associated with an unfavorable metabolic profile, especially when combined with a delayed peak.

Performance of the FreeStyle Libre Flash Glucose Monitoring System during an Oral Glucose Tolerance Test and Exercise in Healthy Adolescents

This study's aim was to assess FreeStyle Libre Flash glucose monitoring (FGM) performance during an oral glucose tolerance test (OGTT) and treadmill exercise in healthy adolescents. This should advance the feasibility and utility of user-friendly technologies for metabolic assessments in adolescents. Seventeen healthy adolescents (nine girls aged 12.8 ± 0.9 years) performed an OGTT and submaximal and maximal treadmill exercise tests in a laboratory setting. The scanned interstitial fluid glucose concentration ([ISFG]) obtained by FGM was compared against finger-prick capillary plasma glucose concentration ([CPG]) at 0 (pre-OGTT), -15, -30, -60, -120 min post-OGTT, pre-, mid-, post- submaximal exercise, and pre- and post- maximal exercise. Overall mean absolute relative difference (MARD) was 13.1 ± 8.5%, and 68% (n = 113) of the paired glucose data met the ISO 15197:2013 criteria. For clinical accuracy, 84% and 16% of FGM readings were within zones A and B in the Consensus Error Grid (CEG), respectively, which met the ISO 15197:2013 criteria of having at least 99% of results within these zones. Scanned [ISFG] were statistically lower than [CPG] at 15 (-1.16 mmol∙L^-1, p < 0.001) and 30 min (-0.74 mmol∙L^-1, p = 0.041) post-OGTT. Yet, post-OGTT glycaemic responses assessed by total and incremental areas under the curve (AUCs) were not significantly different, with trivial to small effect sizes (p ≥ 0.084, d = 0.14-0.45). Further, [ISFGs] were not different from [CPGs] during submaximal and maximal exercise tests (interaction p ≥ 0.614). FGM can be a feasible alternative to reflect postprandial glycaemia (AUCs) in healthy adolescents who may not endure repeated finger pricks.

A New Index of Insulin Sensitivity from Glucose Sensor and Insulin Pump Data: In Silico and In Vivo Validation in Youths with Type 1 Diabetes

Background: Estimation of insulin sensitivity (SI) and its daily variation are key for optimizing insulin therapy in patients with type 1 diabetes (T1D). We recently developed a method for SI estimation from continuous glucose monitoring (CGM) and continuous subcutaneous insulin infusion (CSII) data in adults with T1D (SISP) and validated it under restrained experimental conditions. Herein, we validate in vivo a new version of SISP performing well in daily life unrestrained conditions. Methods: The new SISP was tested in both simulated and real data. The simulated dataset consists of 100 virtual adults of the UVa/Padova T1D Simulator monitored during an open-loop experiment, whereas the real dataset consists of 10 youths with T1D monitored during a hybrid closed-loop meal study. In both datasets, participants underwent two consecutive meals (breakfast and lunch, at 7 and 11 am) with the same carbohydrate content (70 g). Plasma glucose and insulin were measured during each meal to estimate the oral glucose minimal model SI (SIMM). CGM and CSII data were used for SISP calculation, which was then validated against the gold standard SIMM. Results: SISP was estimated with good precision (median coefficient of variation <20%) in 100% of the real and 91% of the simulated meals. SISP and SIMM were highly correlated, both in the simulated and real datasets (R = 0.82 and R = 0.83, P < 0.001), and exhibited a similar intraday pattern. Conclusions: SISP is suitable for estimating SI in both closed- and open-loop settings, provided that the subject wears a CGM sensor and a subcutaneous insulin pump.

Low-density lipoprotein cholesterol levels are associated with first-phase insulin release

AIMS

Prior studies provided evidence that low-density lipoprotein (LDL)-cholesterol-lowering statins reduce cardiovascular events while conveying an increased risk of type 2 diabetes. The aim of this study was to investigate the association between LDL levels and both insulin sensitivity and insulin secretion in a cohort of 356 adult first-degree relatives of patients with type 2 diabetes.

METHODS

Insulin sensitivity was assessed by euglycemic hyperinsulinemic clamp and first-phase insulin secretion was measured by both intravenous glucose tolerance test (IVGTT) and OGTT.

RESULTS

LDL-cholesterol levels were not independently associated with insulin-stimulated glucose disposal. After adjusting for several potential confounders, LDL-cholesterol concentration exhibited a positive independent association with acute insulin response (AIR) during IVGTT and with the OGTT derived Stumvoll first-phase insulin secretion index. When insulin release was adjusted for the underlying degree of insulin sensitivity, using the disposition index (AIR × insulin-stimulated glucose disposal), β-cell function was significantly associated with LDL-cholesterol levels, even after further adjusting for several potential confounders.

CONCLUSIONS

The present results suggest that LDL cholesterol is a positive modulator of insulin secretion. The deterioration in glycemic control observed during treatment with statins might thus be explained by an impairment in insulin secretion due to the cholesterol-lowering effect of statins.

Association between tea consumption and glucose metabolism and insulin secretion in the Shanghai High-risk Diabetic Screen (SHiDS) study

INTRODUCTION

The relationship between tea consumption and glucose metabolism remains controversial. This study investigated the associations of tea consumption with impaired glucose regulation, insulin secretion and sensitivity in Shanghai High-risk Diabetic Screen project.

RESEARCH DESIGN AND METHODS

A total of 2337 Chinese subjects were enrolled in the study from 2014 to 2019. Each participant conducted a 75 g oral glucose tolerance test (OGTT) with five-point glucose and insulin level examined. They also completed a nurse-administered standard questionnaire including tea, coffee, and alcohol consumption, smoking habit, physical activity, education, sleep quality, etc. RESULTS: The result showed that tea consumption was positively associated with plasma glucose levels during OGTT after adjusting for confounder (Ps <0.05) and was associated with worsening glucose tolerance (OR 1.21, 95% CI 1.01-1.44; p=0.034). Strong tea consumption or long-term tea intake (>10 years) had an increased risk of glucose intolerance (all p<0.05). These associations did not vary in participants drinking green tea. In addition, insulin secretion indexes were decreased 7.0%-13.0% in tea consumption group. Logistic regression analysis showed that tea consumption was independently associated with lower insulin secretion (homeostasis model assessment of β-cell function (HOMA-β) (OR 0.81, 95% CI 0.68-0.97; p=0.021); Stumvoll first-phase index (OR 0.81, 95% CI 0.68-0.97; p=0.020)) in a fully adjusted model. Green tea consumption showed a negative association with insulin secretion (HOMA-β (OR 0.77, 95% CI 0.62-0.96; p=0.019)).

CONCLUSIONS

Tea intake is associated with an increased risk of glucose intolerance in a large high-risk diabetic Chinese population. Habitual tea consumption subjects might have lower pancreatic β-cell function.

Circulating spexin levels are influenced by the glycemic status and correlated with pancreatic β-cell function in Chinese subjects

AIMS

Spexin plays a role in regulating glucose metabolism. This study investigated the spexin levels in different glycemic status and its association with insulin secretion in humans.

METHODS

A total of 462 subjects were recruited in this study, including 52 healthy subjects, 106 first-degree relatives (FDRs) of type 2 diabetes mellitus (T2DM), 115 impaired glucose regulation (IGR), 80 newly diagnosed T2DM, and 106 established T2DM. Serum spexin was measured using ELISA. The homeostasis model assessment of insulin resistance (HOMA2-IR) and β-cell function (HOMA2-β), and Stumvoll index estimating first- and second-phase insulin secretion were calculated.

RESULTS

Spexin levels were higher in FDRs [235.53 pg/ml (185.28, 293.95)] and IGR [239.79 pg/ml (191.52, 301.69)], comparable in newly diagnosed T2DM [224.68 pg/ml (187.37, 279.74)], and lower in established T2DM [100.11 pg/ml (78.50, 137.34)], compared with healthy subjects [200.23 pg/ml (160.32, 275.65)]. Spexin levels were negatively correlated with fasting plasma glucose (FPG) (r =  - 0.355, P < 0.001), hemoglobin A1C (HbA1c) (r =  - 0.379, P < 0.001), and HOMA2-IR (r =  -  0.225, P < 0.001), and positively correlated with HOMA2-β (r = 0.245, P < 0.001) after adjusting for age, sex, and BMI. Multivariate linear regression analysis showed that established T2DM and HOMA2-β were independently associated with serum spexin levels.

CONCLUSIONS

Serum spexin levels represented as a bell-shaped curve along the glycemic continuum and is closely related with insulin secretion in humans.

Time-restricted eating did not alter insulin sensitivity or β-cell function in adults with obesity: A randomized pilot study

OBJECTIVE

Decreased insulin sensitivity and impairment of β-cell function predate and predict development of type 2 diabetes mellitus. Time-restricted eating (TRE) might have a benefit for these parameters. The objective of this pilot study was to investigate this possibility.

METHODS

Secondary analysis of a randomized controlled trial comparing 12 weeks of TRE (8-hour eating window) to unrestricted eating (non-TRE) was performed. Participants were adults with overweight or obesity and without diabetes. Two-hour oral glucose tolerance testing was performed at baseline and end-intervention. Glucose tolerance test-derived measures of insulin sensitivity, insulin secretion, and β-cell function were compared between groups.

RESULTS

Participants (17 women/3 men with mean [SD] age 45.5 [12.1] years and BMI 34.1 [7.5] kg/m2 ) with a prolonged eating window (15.4 [0.9] hours) were randomized to TRE (n = 11) or non-TRE (n = 9). The quantitative insulin sensitivity check index (QUICKI), Stumvoll index, Avignon index, insulinogenic index, insulin area under the curve/glucose area under the curve, and oral disposition index did not differ between the TRE and non-TRE groups at end-intervention.

CONCLUSIONS

In adults with overweight or obesity and without diabetes, TRE did not significantly alter insulin sensitivity, insulin secretion, or β-cell function over a 12-week intervention. Whether TRE is beneficial in adults with prediabetes or type 2 diabetes mellitus warrants further investigation.

Perindopril prevents development of obesity and hypertension in middle aged diet-induced obese rat models of metabolic syndrome

AIMS

The therapeutic properties of anti-hypertensive medications that extend beyond blood pressure lowering have started to become important clinical targets in recent years. This study aimed to assess the cardioprotective effects of perindopril in attenuating complications associated with metabolic syndrome in diet induced obese rats.

MAIN METHODS

Male Wistar-Kyoto (WKY) rats aged 16 weeks were fed either standard rat chow (SC) or given a high-fat-high-carbohydrate (HFHC) diet for 20 weeks. Perindopril treatment (1 mg/kg/day) was administered to a subset of WKY rats commencing at week 8 of the 20 week HFHC feeding period. Body weights, food, water and energy intakes, blood pressure, heart rate and glucose tolerance were measured throughout the treatment period. Oxidative stress and inflammatory markers, lipid levels, cardiac collagen deposition, vascular function, aortic and cardiac electrical function were examined after the treatment.

KEY FINDINGS

WKY rats developed metabolic syndrome after 20 weeks of HFHC feeding, evidenced by the presence of abdominal obesity, dyslipidaemia, glucose intolerance and hypertension. Perindopril treatment prevented the development of obesity and hypertension in WKY-HFHC. Perindopril improved blood lipid profiles in HFHC rats with decreases in LDL cholesterol, triglycerides and total cholesterol. Type I collagen levels were decreased in WKY-HFHC rats along with decreases in left ventricle mass. Perindopril treated rats also showed improved cardiac electrical function indicated by decreases in action potential at 90 % of repolarisation in WKY-HFHC rats.

SIGNIFICANCE

These results show that perindopril has a profound effect on preventing the development of metabolic syndrome in animals fed a HFHC diet.

Effect of Vitamin D and/or Calcium Supplementation on Pancreatic β-Cell Function in Subjects with Prediabetes: A Randomized, Controlled Trial

So far, the potential role of vitamin D in β-cell function remains a matter of debate. Therefore, a randomized, placebo-controlled trial (RCT) was conducted to evaluate the effect of a vitamin D supplement with or without calcium on β-cell function in a Chinese population with prediabetes. Two hundred and forty-three subjects were randomly assigned in a 2-by-2 factorial-design RCT to receive either 1600 IU/day vitamin D₃ with/or 500 mg/day calcium for 24 weeks. The results showed that oral administration of vitamin D and calcium could increase the secretion of insulin. Vitamin D-insufficient individuals displayed an increment in the disposition index (adjusted change = 0.31, 95%CI: 0.07, 0.56) after treatment by vitamin D + calcium. It illustrated that supplementation with vitamin D and calcium might improve the function of pancreatic β-cell in prediabetes with low serum 25(OH)D levels. However, further studies are needed to confirm the findings. Given the low vitamin D content in natural foods, it is necessary to fortify processed foods with vitamin D.

Antidiabetic activity of Anredera cordifolia (Ten.) Stennis extracts with different ethanol percentages: an evaluation based on in vitro, in vivo, and molecular studies

Anredera cordifolia (Ten.) Stennis, also known as Binahong (B), is an Indonesian plant used to treat diabetes. The purpose of this study was to determine the best extragent for preparing Binahong extract as an antidiabetic agent using different concentrations of ethanol (50%, 70%, and 96%), labelled as BE50%, BE70%, and BE96%. An alpha-glucosidase inhibiting assay was used to assess the activity. The most active extract was tested in vivo assay using an oral glucose tolerance test (OGTT) and alloxan-high feed diet (alloxan-HFD)-induced diabetes in rats, with glucose level and beta cell Langerhans repair as parameters. A molecular assay was also performed to look into the expression of homeostasis regulator genes on 3T3-L1 adipose cells. The results showed that 96% ethanol extract (BE96%) inhibited alpha-glucosidase the most effectively (IC50 119.78± 11.14 μg/mL). The in vivo assay revealed that the treatment BE96% at 250 mg/kg BW for 21 consecutive days significantly reduced plasma glucose levels in Type 2 DM rats compared to the control group (p ≤ .05) with improved of Langerhans beta cells. BE96% also significantly reduced postprandial glucose levels. At the cellular level, Oil-Red-O staining revealed that differentiated adipocytes treated with BE96% had the highest lipid absorbance (p ≤ .05), compared to the control. BE96% significantly increased the expression of Glucose Transporter Isoform 4 (GLUT4) at the molecular level. It could be concluded that BE96% exhibited the best antidiabetic properties.

The Application of the Insulin to C-Peptide Molar Ratio (ICPR) in Primary Screening for Insulin Antibodies in Type 2 Diabetes Mellitus Patients: A Further Quantitative Study on the Relationship Between ICPR and Insulin Antibodies

Purpose

This study aimed to further quantify the relationship between insulin antibodies (IAs) and the 2-hour insulin to C-peptide molar ratio (2h-ICPR) using a multiple linear regression model in T2DM patients.

Methods

A total of 274 T2DM patients from April 2019 to December 2022 in Xiang'an Hospital of Xiamen University were included in this study. Multiple Linear Model Fitting was conducted on the candidate independent variables (age, BMI, HbA1c, and 2h-ICPR) for the multiple linear regression. The linear relationship between insulin antibodies (IAs) and the significant independent variables was presented by making multiple linear regression equations.

Results

The total demographic characteristics of the included patients were as follows: age (51.92±13.10 years), BMI (24.94±3.99 kg/m²), HbA1c (9.70±2.39%), 2h-ICPR (0.12±0.11), and IAs (0.37±1.12COI). Linear relationships of independent variables: age (r=0.163, p=0.007), 2h-ICPR (r=0.259, p=0.001), BMI (r=0.007, p=0.907) and 2h-ICPR (r=0.092, p=0.129). Multiple linear regression: age (unstandardized β=0.014, 95% CI: 0.004-0.024, p=0.004), 2h-ICPR (unstandardized β=2.758, 95% CI: 1.555-3.962, p≤0.001). The regression equation: .

Conclusion

The quantitative relationship between 2h-ICPR and insulin antibodies was . 2h-ICPR can be a preliminary screening indicator for insulin antibody testing in patients with type 2 diabetes.

Dysglycemia With Impaired Insulin Secretion After Resection of a High-Molecular-Weight IGF-II-Producing Tumor

Analysis of insulin and related glucoregulatory hormone secretion following high-molecular-weight insulin-like growth factor II (HMW-IGF-II)-releasing tumor excision has never been reported. In a man with chronic hypoglycemia-plasma glucose (PG), 2.1 mmol/L with undetectable serum insulin, less than 7.2 pmol/L on admission-the cause of the hypoglycemia was HMW-IGF-II in the serum secreted by an intrathoracic benign pleural solitary fibrous tumor (size: 15 × 17 × 12 cm). Removal of the tumor nullified serum HMW-IGF-II and hypoglycemia. Postoperative glucose metabolism was evaluated day 272 by 75 g oral glucose tolerance test (OGTT) and on days 5, 202, and 990 by fasted sampling. Glycated hemoglobin A1c (HbA1c) was 37 to 41 mmol/mol, fasting PG was 5.3 to 5.4 mmol/L, and 2-hour PG at 75 g OGTT was 6.9 mmol/L, indicating that he was at the prediabetes stage. Homeostasis Model Assessment 2 of Insulin Resistance and Homeostasis Model Assessment 2 of β-Cell levels were within the normal range but the Stumvoll first phase was lowered. Insulin sensitivity and secretion were compared to age-, sex-, and body mass index-matched controls with normal glucose metabolism. Long-term HMW-IGF-II exposure of pancreatic islet β cells caused the functional impairment, that is, suppressed glucose-stimulated insulin secretion (GSIS), leading to nondiabetic hyperglycemia. This fact suggests long-term HMW-IGF-II exposure of the islet β cell specifically dampens GSIS.

No Indices of Increased Type 2 Diabetes Risk in Individuals with Reactive Postprandial Hypoglycemia

Reactive postprandial hypoglycemia (RPH) is an understudied condition that lacks clinical definition, knowledge of future health implications, and an understanding of precise underlying mechanisms. Therefore, our study aimed to assess the glycemic response after glucose ingestion in individuals several years after the initial evaluation of RPH and to compare glucose regulation in individuals with RPH vs. healthy volunteers. We assessed the inter- and intra-individual differences in glucose, insulin, and C-peptide concentrations during 5-h oral glucose tolerance tests (OGTTs); the surrogate markers of insulin resistance (HOMA-IR and Matsuda index); and beta-cell function (distribution index and insulinogenic index). The study included 29 subjects with RPH (all females, aged 39 (28, 46) years) and 11 sex-, age-, and body mass index (BMI)-matched controls. No biochemical deterioration of beta-cell secretory capacity and no progression to dysglycemia after 6.4 ± 4.2 years of follow-up were detected. RPH subjects were not insulin resistant, and their insulin sensitivity did not deteriorate. RPH subjects exhibited no differences in concentrations or in the shape of the glucose-insulin curves during the 5-h OGTTs compared to age- and BMI-matched controls. No increased incident type 2 diabetes risk indices were evident in individuals with RPH. This dictates the need for further research to investigate the magnitude of future diabetes risk in individuals experiencing RPH.

Effects of Roux-en-Y Gastric Bypass and Sleeve Gastrectomy on β-Cell Function at 1 Year After Surgery: A Systematic Review

Bariatric surgery is a highly effective obesity treatment resulting in substantial weight loss and improved glucose metabolism. We hereby aimed to summarize available evidence of the effect of the 2 most common bariatric surgery procedures, Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG), on dynamic measures of β-cell function (BCF). A systematic search of the literature was conducted in 3 bibliographic databases for studies reporting effects of RYGB and/or SG on BCF assessed using dynamic metabolic perturbation (oral or intravenous bolus stimulation), performed before and 1 year (±3 months) after surgery. Twenty-seven unique studies (6 randomized controlled trials and 21 observational studies), involving a total of 1856 obese adults, were included for final analysis. Twenty-five and 9 studies report effects of RYGB and SG on BCF, respectively (7 studies compared the 2 procedures). Seven studies report results according to presurgical diabetes status. Owing to variable testing procedures and BCF indices reported, no meta-analysis was feasible, and data were summarized qualitatively. For both surgical procedures, most studies suggest an increase in BCF and disposition index, particularly when using oral stimulation, with a more pronounced increase in diabetic than nondiabetic individuals. Additionally, limited indications for greater effects after RYGB versus SG were found. The quality of the included studies was, in general, satisfactory. The considerable heterogeneity of test protocols and outcome measures underscore the need for a harmonization of BCF testing in future research.

Interscapular fat is associated with impaired glucose tolerance and insulin resistance independent of visceral fat mass

OBJECTIVE

Dysregulated body fat distribution is a major determinant of various diseases. In particular, increased visceral fat mass and ectopic lipids in the liver are linked to metabolic disorders such as insulin resistance and type 2 diabetes. Furthermore, interscapular fat is considered to be a metabolically active fat compartment.

METHODS

This study measured interscapular fat mass and investigated its relationship with glucose metabolism in 822 individuals with a wide range of BMI values and different glucose tolerance statuses. Magnetic resonance imaging was used to quantify body fat depots, and an oral glucose tolerance test was performed to determine glucose metabolism.

RESULTS

Elevated interscapular fat mass was positively associated with age, BMI, and total body, visceral, and subcutaneous adipose tissue mass. High interscapular fat mass associated with elevated fasting glucose levels, glucose levels at 2 hours during the oral glucose tolerance test, glycated hemoglobin, and insulin resistance, independent of sex, age, and total body and visceral fat mass.

CONCLUSIONS

In conclusion, interscapular fat might be a highly specific fat compartment with a potential impact on glucose metabolism and the pathogenesis of diabetes mellitus.

Lower Glucose Effectiveness Is Associated with Postprandial Hyperglycemia in Obese/Overweight Men, Independently of Insulin Secretion

The role of glucose effectiveness on postprandial hyperglycemia in daily life is not fully studied. Here, we examined the association between SgIo, an index of glucose effectiveness calculated from a 75 g oral glucose tolerance test, and the indices of hyperglycemia in obese/overweight men. SgIo was significantly associated with 1,5-anhydroglycitol, a biochemical marker for postprandial hyperglycemia. The receiver operating characteristic analyses of SgIo and oral disposition index for detecting the subjects with 1,5-anhydroglycitol < 14 μg/mL revealed that the areas under the curves were 0.77 and 0.76, while the cutoff points (sensitivity, selectivity) were 2.53 (0.9, 0.7) and 2.06 (0.36, 0.79), respectively. Both the SgIo < 2.53 category and the disposition index < 2.06 category were significantly associated with the percentages of meals with postprandial glucose levels ≥ 200 mg/dL, and the percentages of time when continuous glucose monitoring sensor readings were ≥200 mg/dL. After adjustment with disposition index, 45.5% of the subjects with the SgIo < 2.53 category had their 1,5-anhydroglycitol < 14 μg/mL, while, in the SgIo ≥ 2.53 category, 3.6% of the subjects had the hyperglycemia (p < 0.001). In addition, there were tendencies toward higher and lower SgIo quartile categories in subjects with walking (≥8000 steps) ≥60% of days and with noodle ingestion ≥20% of meals, respectively (p for trend, 0.008 and 0.038). In conclusion, lower glucose effectiveness is associated with postprandial hyperglycemia in the daily life of obese/overweight men, independently of insulin secretion. Lifestyles such as habits of walking and noodle ingestion are significantly associated with higher and lower glucose effectiveness, respectively.

Effects of gender-affirming hormone therapy on cardiovascular risk factors focusing on glucose metabolism in an Austrian transgender cohort

Objective

We aimed to investigate the effect of gender-affirming hormone therapy (GAHT) on cardiovascular disease risk factors focusing on glucose tolerance.

Patients and Methods

This primarily translational study enrolled 16 transgender persons assigned female at birth (AFAB), 22 assigned male at birth (AMAB), and 33 age- and BMI-matched cisgender controls at the Medical University of Vienna from 2013 to 2020. A 3-Tesla MRI scan to measure intramyocardial, pancreatic, hepatic fat content and subcutaneous-to-visceral adipose tissue ratio (SAT/VAT-ratio), an oral glucose tolerance test (oGTT), bloodwork including brain natriuretic peptide (pro-BNP), sex hormones and two glucose-metabolism related biomarkers (adiponectin, betatrophin) were performed.

Results

Estrogen intake was associated with higher fasting insulin (p = 0.034) and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) (p = 0.037), however, lower HbA1c levels (p = 0.031) in AMAB than cisgender males. Adiponectin (p = 0.001) and betatrophin (p = 0.034) levels were higher in AMAB than cisgender males, but similar to cisgender females. Compared to cisgender females, AFAB displayed no differences in glucose metabolism or SAT/VAT-ratio. AFAB had lower pro-BNP levels (p = 0.014), higher liver enzymes (AST: p = 0.011; ALT: p = 0.012) and lower HDL levels (p = 0.017) than cisgender females, but comparable levels to cisgender males. AMAB showed an increased heart rate (p < 0.001) and pro-BNP (p = 0.002) levels, but a more favorable SAT/VAT-ratio (p = 0.013) and lower creatine kinase (CK) (p = 0.001) than cisgender males. There were no relevant differences in organ fat content between transgender persons and their respective cisgender controls.

Conclusion

In AMAB, most investigated parameters adapted to levels seen in cisgender females except for parameters related to fasted insulin resistance. AMAB should be monitored with respect to the development of insulin resistance.

Differences in Insulin Sensitivity, Secretion, and the Metabolic Clearance Rate of Glucose in Newly Diagnosed Type 2 Diabetes Mellitus Patients: The Influences of Body Mass Index and Fatty Liver

Background: Obesity and nonalcoholic fatty liver disease are strongly associated with type 2 diabetes mellitus (T2DM), affecting insulin sensitivity and β-cell function. They interact, exacerbating the development of hyperinsulinemia to T2DM. Methods: Through oral glucose tolerance and insulin secretion tests, the relationships between insulin sensitivity and secretion, glucose clearance, body mass index (BMI), and fatty liver were studied in newly diagnosed T2DM patients. The homeostasis model assessment of insulin resistance (HOMA-IR), homeostasis model assessment of β-cell function (HOMA-β), insulin sensitivity index (ISI), and metabolic clearance rate (MCR) of glucose were calculated to analyze insulin sensitivity and β-cell function. Results: There were no differences in HOMA-IR, HOMA-β, first-phase insulin secretion (1st PH), second-phase insulin secretion (2nd PH), ISI, or MCR between lean fatty liver and lean nonfatty liver patients. Both overweight/obesity (ow/ob) and patients with fatty liver increased HOMA-IR, and decreased ISI and MCR. In the ow/ob subgroup, patients with fatty liver had severe insulin resistance but greater HOMA-β, 1st PH, and 2nd PH than individuals with nonfatty liver. The difference in MCR between fatty liver and nonfatty liver groups was not significant. Conclusion: BMI and hepatic steatosis are independent determinants of increased insulin resistance and decreased MCR. However, it is steatosis, not BMI, related to the increase in insulin secretion.

The Association of Measures of Cardiovascular Autonomic Function, Heart Rate, and Orthostatic Hypotension With Incident Glucose Disorders: The Cardiovascular Health Study

OBJECTIVE

The autonomic nervous system (ANS) innervates pancreatic endocrine cells, muscle, and liver, all of which participate in glucose metabolism. We tested whether measures of cardiovascular ANS function are independently associated with incident diabetes and annual change in fasting glucose (FG) levels as well as with insulin secretion and insulin sensitivity in older adults without diabetes.

RESEARCH DESIGN AND METHODS

Heart rate (HR) and measures of HR variability (HRV) were derived from 24-h electrocardiographic monitoring. Blood pressure, seated and standing, was measured. Cox proportional hazards models and linear mixed models were used to analyze the associations between HRV, HR, and orthostatic hypotension (SBP >20 mmHg decline) and incident diabetes or longitudinal FG change.

RESULTS

The mean annual unadjusted FG change was 1 mg/dL. Higher detrended fluctuation analyses (DFA) values, averaged over 4-11 (DFA1) or 12-20 beats (DFA2)-reflecting greater versus less organization of beat-to-beat intervals-were associated with less FG increase over time (per 1-SD increment: DFA1: -0.49 mg/dL/year [-0.96, -0.03]; DFA2: -0.55 mg/dL/year [-1.02, -0.09]). In mutually adjusted analyses, higher SD of the N-N interval (SDNN) was associated with less FG increase over time (per 1-SD increment: SDNN: -0.62 mg/dL/year [-1.22, -0.03]). Higher values of DFA1, DFA2, and SDNN were each associated with greater insulin secretion and insulin sensitivity but not with incident diabetes. We observed no association of HR or orthostatic hypotension with diabetes or FG change.

CONCLUSIONS

Specific measures of cardiac autonomic function are prospectively related to FG level changes and insulin secretion and action.

Circulating 1,5-Anhydroglucitol as a Biomarker of ß-cell Mass Independent of a Diabetes Phenotype in Human Subjects

CONTEXT

During an asymptomatic prediabetic state, the functional ß-cell mass decreases to a critical threshold, triggering diabetes and related symptoms. To date, there are no reliable readouts able to capture in vivo a potential drop of the ß-cell mass.

OBJECTIVE

Beside its use as a short-term marker of glycemic control, the deoxyhexose 1,5-anhydroglucitol was identified in rodents as a circulating biomarker of the functional ß-cell mass already in the asymptomatic prediabetic stage. The present study investigated the putative corresponding relevance of circulating 1,5-anhydroglucitol in different human cohorts.

METHODS

We analyzed clinical and blood parameters in patients with established type 2 diabetes and subjects considered at high risk of developing diabetes, as well as patients with no history of diabetes scheduled for pancreaticoduodenectomy.

RESULTS

Circulating 1,5-anhydroglucitol was reduced in type 2 diabetic patients, negatively correlating with fasting plasma glucose (P < 0.0001) and hemoglobin A1c (P < 0.0001). In healthy subjects, 1,5-AG levels positively correlated with body mass index (P = 0.004) and Homeostatic Model Assessment of Insulin Resistance %S (P < 0.03) and was particularly high in nondiabetic obese individuals, potentially accounting for compensatory ß-cell expansion. Patients with no history of diabetes undergoing pancreaticoduodenectomy exhibited a 50% reduction of circulating 1,5-anhydroglucitol levels following surgery leading to an acute loss of their ß-cell mass (P = 0.002), regardless their glucose tolerance status.

CONCLUSION

In summary, plasma concentration of 1,5-anhydroglucitol follows the ß-cell mass and its noninvasive monitoring may alert about the loss of ß cells in subjects at risk for diabetes, an event that cannot be captured by other clinical parameters of glycemic control.

Comprehensive validation of fasting-based and oral glucose tolerance test-based indices of insulin secretion against gold standard measures

INTRODUCTION

With pre-diabetes and diabetes increasingly recognized as heterogeneous conditions, assessment of beta-cell function is gaining clinical importance to identify disease subphenotypes. Our study aims to comprehensively validate all types of surrogate indices based on oral glucose tolerance test (OGTT) and fasting measurements in comparison with gold standard methods.

RESEARCH DESIGN AND METHODS

The hyperglycemic clamp extended with glucagon-like peptide 1 (GLP-1) infusion and intravenous glucose tolerance test (IVGTT), as well as OGTT, was performed in two well-phenotyped cohorts. The gold standard-derived indices were compared with surrogate insulin secretion markers, derived from fasting state and OGTT, using both Pearson's and Spearman's correlation coefficients. The insulin-based and C-peptide-based indices were analyzed separately in different groups of glucose tolerance and the entire cohorts.

RESULTS

The highest correlation coefficients were found for area under curve (AUC) (I_0-30)/AUC (G_0-30), I₃₀/G₃₀, first-phase Stumvoll and Kadowaki model. These indices have high correlation coefficients with measures obtained from both insulin and C-peptide levels from IVGTT and hyperglycemic clamp. AUC (I_0-120)/AUC (G_0-120), BIGTT-AIR_0-60-120, I₃₀/G₃₀, first-phase Stumvoll and AUC (I_0-30)/AUC (G_0-30) demonstrated the strongest association with incretin-stimulated insulin response.

CONCLUSIONS

We have identified glucose-stimulated and GLP-1-stimulated insulin secretion indices, derived from OGTT and fasting state, that have the strongest correlation with gold standard measures and could be potentially used in future researches and clinical practice.

Diabetic family history in young Japanese persons with normal glucose tolerance associates with k-means clustering of glucose response to oral glucose load, insulinogenic index and Matsuda index

Aims

The present study aimed to clarify the relationships between diabetic family history (FH), and dysglycemic response to the oral glucose tolerance test (OGTT), insulin secretion, and insulin sensitivity in young Japanese persons with normal glucose tolerance (NGT).

Methods

We measured plasma glucose (PG) and immunoreactive insulin levels in 1,309 young Japanese persons (age <40 years) with NGT before and at 30, 60, and 120 min during a 75-g OGTT. Dysglycemia during OGTT was analyzed by k-means clustering analysis. Body mass index (BMI), blood pressure (BP), and lipids were measured. Insulin secretion and sensitivity indices were calculated.

Results

PG levels during OGTT were classified by k-means clustering analysis into three groups with stepwise decreases in glucose tolerance even among individuals with NGT. In these clusters, proportion of males, BMI, BP and frequency of FH were higher, and lipid levels were worse, together with decreasing glucose tolerance. Subjects with a diabetic FH showed increases in PG after glucose loading and decreases in insulinogenic index and Matsuda index.

Conclusions

Dysglycemic response to OGTT by k-means clustering analysis was associated with FH in young Japanese persons with NGT. FH was also associated with post-loading glucose, insulinogenic index, and Matsuda index.

Impaired pancreatic beta-cell function after a single dose of oral iron: a before-and-after (pre-post) study

INTRODUCTION

Although in vitro and animal studies have shown that iron loading in pancreatic beta-cells impaired insulin secretion, no human studies have documented the acute effects of oral iron on beta-cell insulin secretory capacity. In this study, we determined beta-cell insulin secretory capacity at baseline and after a single oral dose of iron (ferrous sulphate, 120 mg elemental iron) in healthy male individuals.

METHODS

Fifteen healthy male volunteers underwent an oral glucose tolerance test (OGTT) to document baseline glucose tolerance and insulin secretion kinetics (baseline OGTT). One week later, the same subjects underwent a second OGTT, two hours after an oral dose of ferrous sulfate (120 mg of elemental iron) (post-iron OGTT). Changes in disposition index, insulin secretion kinetics, glucose tolerance, insulin resistance, insulin clearance, and iron-related parameters in serum were determined.

RESULTS

Compared to baseline OGTT, the areas under the curve (AUC) for serum iron and transferrin saturation increased by 125% and 118% respectively, in the post-iron OGTT. The disposition index decreased by 20% (p=0.009) and the AUC for glucose concentrations increased by 5.7% (p<0.001) during the post-iron OGTT. The insulin secretion rate was marginally lower during the first hour (-3.5%, p=0.63), but became significantly higher during the second hour (22%, p=0.005) of the post-iron OGTT. Insulin resistance and insulin clearance rate were not affected by iron intake.

CONCLUSION

The decrease in disposition index and glucose tolerance observed after the oral dose of iron points to an acute iron-induced impairment in pancreatic beta-cell insulin secretory capacity. This article is protected by copyright. All rights reserved.