Characterization of β-cell function and insulin resistance in overweight Chinese adolescents with normal glucose tolerance

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.

Impact of triglycerides and waist circumference on insulin resistance and β-cell function in non-diabetic first-degree relatives of type 2 diabetes

BACKGROUND

Although there is abundant evidence indicating the relative contribution of insulin resistance (HOMA-IR) and β-cell dysfunction (HOMA-β) among first-degree relatives (FDRs) of Type 2 DM patients, few studies reported the association between HOMA-IR and HOMA-β with metabolic syndrome. Our objective was to evaluate the impact of metabolic syndrome factors on HOMA-IR, HOMA-β and glycoproteins in non-diabetic FDRs.

METHODS

In this study, 103 Yemeni male subjects aged 25-42 years, with BMI < 25 kg/m² were examined, 39 of whom were normal subjects with no family history of diabetes served as control and 64 subjects were non-diabetic FDRs of Type 2 DM patients.

RESULTS

Both glycoproteins, glycated haemoglobin (HbA1c) and fructosamine as well as insulin, HOMA-IR and HOMA-β were significantly (p = 4.9 × 10^-9; 6.0 × 10^-8; 6.6 × 10^-12; 1.3 × 10^-7; 5.5 × 10^-12, respectively) higher in non-diabetic FDRs as compared to control group. Fasting plasma glucose, though within normal range, were significantly (p = 0.026) higher in non-diabetic FDRs. Linear regression analysis showed that both TG and WC are the main metabolic syndrome factors that significantly increased HOMA-IR (B = 0.334, p = 1.97 × 10^-6; B = 0.024, p = 1.05 × 10^-5), HOMA-β (B = 16.8, p = 6.8 × 10^-5; B = 0.95, p = 0.004), insulin (B = 16.5, p = 1.2 × 10^-6; B = 1.19, p = 8.3 × 10^-6) and HbA1c (B = 0.001, p = 0.034; B = 0.007, p = 0.037).

CONCLUSION

Triglyceride and WC are the important metabolic syndrome factors associated with insulin resistance, basal β-cell function and insulin levels in non-diabetic FDR men of Type 2 DM patients. Moreover, FDRs showed insulin resistance with compensatory β-cell function (hyperinsulinaemia) suggesting that insulin resistance precede the development of pancreatic β-cell dysfunction in individuals at risk of Type 2 DM.

Metabolically healthy overweight adolescents: definition and components

PURPOSE

In adolescents, the definition and clinical implications of metabolically healthy overweight (MHO) status have not been established. This study aimed to investigate the prevalence of MHO according to its most widespread definition, which is based on metabolic syndrome (MS), and to explore further metabolic indicators such as Homeostatic Model Assessment of Insulin Resistance, total cholesterol, low-density lipoprotein cholesterol, alanine aminotransferase, and C-reactive protein levels, together with metabolic health predictors in a sample of adolescents attending a pediatric obesity clinic.

METHODS

Data from 487 adolescents categorized as overweight (52.6% females, 88.1% white), with a mean body mass index (BMI) z-score of 2.74 (±1.07 standard deviation [SD]), and a mean age of 14.4 years (±2.2 SD) were cross-sectionally analyzed. From this original sample, a subsample of 176 adolescents underwent a second assessment at 12 (±6 SD) months for longitudinal analysis.

RESULTS

From the 487 adolescents originally analyzed, 200 (41.1%) were categorized as MHO, but only 93 (19.1%) had none of the metabolic indicators considered in this study. According to longitudinal analysis, 30 of the 68 adolescents (44%) categorized as MHO at baseline became non-MHO over time. BMI z-score was the best predictor of metabolic health both in cross-sectional and longitudinal analyses. Increased BMI z-score reduced the odds of being categorized as MHO (odds ratio [OR], 0.6; 95% confidence interval [CI], 0.4-0.9; P=.008) and increased the odds of having hypertension (OR 2.1, 95% CI: 1.4-3.3, P=0.001), insulin resistance (OR, 2.4; 95% CI, 1.4-4.1, P=0.001), or a proinflammatory state (OR, 1.2; 95% CI, 1.1-1.3, P=0.002).

CONCLUSION

Diagnosis of MHO should not be exclusively based on MS parameters, and other metabolic indicators should be considered. Adolescents categorized as overweight should participate in weight-management lifestyle interventions regardless of their metabolic health phenotype.

Differences in early-phase insulin secretion and glucose disposition index between aged and middle-aged patients with newly diagnosed type 2 diabetes

AIM

This cross-sectional study aimed to investigate the differences in β-cell function and insulin sensitivity between newly diagnosed aged and middle-aged type 2 diabetes mellitus (T2DM) patients.

METHODS

A total of 206 newly diagnosed T2DM patients aged ≥60 years (A-DM group) and 206 newly diagnosed sex- and glycated hemoglobin-matched T2DM patients aged <60 years (MA-DM group) were recruited. All patients underwent the 75-g oral glucose tolerance test. Plasma glucose, lipid profiles, liver and renal function, glycated hemoglobin, and insulin were measured. Homeostasis model assessment for insulin resistance, quantitative insulin sensitivity check index, area under the curve of glucose during 0-30 min (GluAUC30) × area under the curve of insulin during 0-30 min (InsAUC30) and β-cell function indexes were calculated.

RESULTS

The mean age of the total 412 patients (356 men and 56 women) was 59.76 ± 13.32 years. There were no significant differences in GluAUC120 between the two groups (106.89 ± 27.70 in A-DM vs 108.32 ± 27.58 in MA-DM; P = 0.6), but ΔI30/ΔG30, InsAUC30 and GluAUC30 × InsAUC30 levels were significantly higher in the A-DM group than in the MA-DM group (3.55 ± 4.54 vs 2.53 ± 3.83; P = 0.014, and 39.19 ± 32.19 vs 32.71 ± 28.81; P = 0.032, 675.05 ± 475.60 vs 584.56 ± 450.23; P = 0.048, respectively). The glucose disposition index (GDI) of the A-DM group was statistically higher than that of the MA-DM group (0.38 ± 0.40 vs 0.30 ± 0.35; P = 0.018). Age was positively associated with ΔI30/ΔG30 (r = 0.117; P = 0.017) and GDI (r = 0.147; P = 0.003), but had no correlation with InsAUC30, InsAUC120 or GluAUC30 × InsAUC30. After multiple adjustments for confounders, including sex, body mass index, glycated hemoglobin, triglyceride, total cholesterol and high-density lipoprotein cholesterol, age was positively associated with ΔI30/ΔG30, InsAUC30, InsAUC120, GluAUC30 × InsAUC30 and GDI.

CONCLUSIONS

Aged patients have relatively higher early-phase insulin secretion and GDI than middle-aged patients in newly diagnosed T2DM. Geriatr Gerontol Int 2020; ••: ••-••.

Insulin resistance and β-cell dysfunction and the relationship with cardio-metabolic disorders among women with polycystic ovary syndrome

OBJECTIVE

To investigate both independent and combined effects of insulin resistance and β-cell dysfunction on cardio-metabolic abnormalities in polycystic ovary syndrome (PCOS).

DESIGN

A national epidemiologic survey was performed in reproductive aged females in China from October 2007 to September 2011.

METHODS

A total of 824 PCOS and 2715 non-PCOS were included. The Rotterdam Criteria were applied for PCOS diagnosis. We used the homeostasis model assessment of insulin resistance (HOMA-IR) and HOMA of β-cell function (HOMA-β) to evaluate insulin resistance and β-cell dysfunction, respectively.

RESULTS

Compared with non-PCOS, PCOS showed a higher index of HOMA-IR and HOMA-β, and a higher prevalence of obesity, central obesity, and dyslipidaemia. High HOMA-IR was independently related to a high prevalence of obesity, central obesity, dyslipidaemia, and high blood glucose in PCOS. In contrast, a low index of HOMA-β index was independently correlated with a low prevalence of obesity, and central obesity, but negatively correlated with an elevated prevalence of high blood glucose in PCOS. In addition, proportion of insulin resistance was higher than that of β-cell dysfunction in PCOS with cardio-metabolic disorders. β-cell dysfunction was negatively correlated with the prevalence of central obesity and obesity.

CONCLUSIONS

Insulin resistance and β-cell dysfunction independently affected cardio-metabolic abnormalities in PCOS, while insulin resistance was correlated with a higher prevalence of cardio-metabolic abnormalities than that of β-cell dysfunction. Moreover, β-cell dysfunction and insulin resistance showed divergent correlations with obesity in PCOS.

Insulin Resistance and β-Cell Dysfunction in Relation to Cardiometabolic Risk Patterns

CONTEXT

Insulin resistance (IR) and β-cell dysfunction are two major defects synergistically inducing the development of diabetes and related cardiometabolic disorders.

OBJECTIVE

To investigate the independent and joint associations of IR and β-cell dysfunction with the prevalence of multiple cardiometabolic disorders, including obesity, central obesity, diabetes, dyslipidemia, and hypertension.

DESIGN AND SETTINGS

A nationally representative population of 93,690 Chinese adults.

MAIN OUTCOME MEASURES

IR and β-cell dysfunction were assessed by the homeostasis model assessment of IR (HOMA-IR) and of β-cell function (HOMA-B), respectively.

RESULTS

High HOMA-IR was independently associated with high prevalence of all estimated cardiometabolic disorders, whereas low HOMA-B was independently associated with high prevalence of diabetes, dyslipidemia, and hypertension but low prevalence of obesity and central obesity. When examined jointly, the associations of HOMA-IR and HOMA-B with multiple cardiometabolic disorders showed different patterns with varying magnitudes. The strongest joint associations were observed for diabetes, with low HOMA-B associated with high prevalence of diabetes regardless of HOMA-IR; joint associations with dyslipidemia and hypertension prevalence appeared to be additive and had moderate changing trends; and low HOMA-B was not associated with high prevalence of obesity or central obesity unless combined with high HOMA-IR.

CONCLUSION

IR was associated with more prevalent cardiometabolic disorders than was β-cell dysfunction, and combinations of IR and β-cell dysfunction showed distinct relations with cardiometabolic risk patterns in Chinese adults.

Anti-diabetic effect of Alpinia oxyphylla extract on 57BL/KsJ db-/db- mice

Diabetes mellitus is characterized by high blood glucose levels. Increased levels of reactive oxygen species (ROS) may disrupt insulin signaling and result in insulin resistance. The Alpinia oxyphylla extract (AOE) possesses powerful antioxidant activity and may therefore inhibit the development of insulin resistance. The objective of the present study was to determine the effects of AOE on blood glucose, insulin and lipid levels in a type II diabetic nephropathy animal model (C57BIKsj db-/db-). All experiments were performed on male C57BL/Ks DB/DB and db-/db- mice that were left to acclimatize for 1 week prior to the experimental period. AOE was administered to these mice at different dosages (100, 300 and 500 mg/kg) for 8 weeks. The results demonstrated that AOE did not affect mouse weight, while blood glucose concentrations were found to significantly decrease in a dose-dependent manner (P<0.05). The effect of administering 500 mg/kg AOE (AOE500) to db-/db- mice was tested further. Treatment with AOE500 for 8 weeks led to improved glucose tolerance and reduced plasma insulin concentrations (P<0.05), as well as a significant decrease in triglyceride concentrations (P<0.05) and levels of total cholesterol (P<0.05) in db-/db- mice. Furthermore, treatment with AOE500 decreased the concentration of malondialdehyde, elevated the concentration of glutathione and increased the activities of the antioxidant enzymes superoxide dismutase and peroxidase (P<0.05) in the livers of db-/db- mice. Meanwhile, AOE-treated mice exhibited significantly reduced urine albumin, creatinine and blood urea nitrogen excretion (P<0.05). In parallel, the upregulated expression of phosphatase and tensin homolog (PTEN) in the liver and kidneys of db-/db- mice was impaired following AOE500 treatment. The results of the present study suggest that AOE regulates blood glucose and lipid levels and improves renal function by mediating oxidative stress and PTEN expression at the onset of type II diabetes mellitus.

Male predominance in ketosis-prone diabetes mellitus

The incidence of ketosis-prone diabetes mellitus (KPDM) shows a higher prevalence in men. The clear male predominance of this syndrome and its underlying pathogenesis mechanisms are unclear. KPDM, once described as atypical diabetes mellitus, idiopathetic type 1 diabetes (type 1B diabetes) and flatbush diabetes, is an uncommon form of diabetes characterized by severe reversible insulin deficiency. KPDM was first described and mostly observed in males of African-American descent and recently in Asian populations, including Japanese and Chinese. Patients with KPDM often present acutely with diabetic ketoacidosis without any immunological autoantibody to islet antigens of classic type 1 diabetes but demonstrate clinical and metabolic features of type 2 diabetes. Accumulating data indicated that gender-related body fat distribution, hormonal and genetic factors are associated with the diabetic process and the human glucose homeostasis and metabolism. A controversial question is whether and to what degree those factors contribute to the phenomenon of male predominance in KPDM. The present review focuses on the role of gender hormones and other potential precipitating factors in explaining the male predominance in KPDM patients.

Gender-dimorphic regulation of DJ1 and its interactions with metabolic proteins in streptozotocin-induced diabetic rats

Regulation of DJ1 is associated with a number of human diseases. To determine the involvement of DJ1 in progression of diabetes in a gender-dependent manner, we investigated its tissue-specific expression in streptozotocin (STZ)-induced diabetic male and female rats in this study. In animal experiments, females showed greater susceptibility towards developing diabetes because of lower insulin secretion and higher blood glucose levels as compared to male diabetic rats upon exposure to STZ. Immunoblotting confirmed sexually dimorphic regulation of DJ1 in various metabolic tissues such as the liver, pancreas and skeletal muscle. Immunofluorescence analysis revealed the location as well as reinforced the gender-dependent expression of DJ1 in hepatic tissue. Co-immunoprecipitation assay identified several interacting proteins with DJ1 whose functions were shown to be involved in various metabolic pathways viz. antioxidative and stress defence system, protein and methionine metabolism, nitrogen metabolism, urea metabolism, etc. Using GeneMANIA, a predictive web interface for gene functions, we showed for the first time that DJ1 may regulate T1DM via the JNK1 pathway, suggesting DJ1 interacts with other proteins from various metabolic pathways. We anticipate that the current data will provide insights into the aetiology of T1DM.

Chlorophytum borivilianum root extract maintains near normal blood glucose, insulin and lipid profile levels and prevents oxidative stress in the pancreas of streptozotocin-induced adult male diabetic rats

The effect of C. borivilianum root on blood glucose, glycated hemoglobin (HbAIc), insulin and lipid profile levels in diabetes mellitus are not fully understood. This study therefore investigated the effect of C. borivilianum root on the above parameters and oxidative stress of the pancreas in diabetes.

METHODS

C. borivilianum root aqueous extract (250 and 500 mg/kg/day) was administered to streptozotocin (STZ)-induced male diabetic rats for 28 days. Body weight, blood glucose, HbA1c, insulin, lipid profile levels and glucose homeostasis indices were determined. Histopathological changes and oxidative stress parameters i.e. lipid peroxidation (LPO) and antioxidant enzymes activity levels of the pancreas were investigated.

RESULTS

C. borivilianum root extract treatment to diabetic rats maintained near normal body weight, blood glucose, HbA1c, lipid profile and insulin levels with higher HOMA-β cell functioning index, number of Islets/pancreas, number of β-cells/Islets however with lower HOMA-insulin resistance (IR) index as compared to non-treated diabetic rats. Negative correlations between serum insulin and blood glucose, HbA1c, triglyceride (TG) and total cholesterol (TC) levels were observed. C. borivilianum root extract administration prevented the increase in lipid peroxidation and the decrease in activity levels of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) with mild histopathological changes in the pancreas of diabetic rats.

CONCLUSIONS

C. borivilianum root maintains near normal levels of these metabolites and prevented oxidative stress-induced damage to the pancreas in diabetes.