Index of glucose effectiveness derived from oral glucose tolerance test

Subclinical Reactive Hypoglycemia with Low Glucose Effectiveness-Why We Cannot Stop Snacking despite Gaining Weight

Obesity has grown worldwide owing to modern obesogenic lifestyles, including frequent snacking. Recently, we studied continuous glucose monitoring in obese/overweight men without diabetes and found that half of them exhibit glucose levels less than 70 mg/dL after a 75-g oral glucose load without notable hypoglycemic symptoms. Interestingly, people with "subclinical reactive hypoglycemia (SRH)" snack more frequently than those without it. Since the ingestion of sugary snacks or drinks could further induce SRH, a vicious cycle of "Snacking begets snacking via SRH" can be formed. Glucose effectiveness (Sg) is an insulin-independent mechanism that contributes to most of the whole-body glucose disposal after an oral glucose load in people without diabetes. Our recent data suggest that both higher and lower Sg are associated with SRH, while the latter but not the former is linked to snacking habits, obesity, and dysglycemia. The present review addresses the possible role of SRH in snacking habits in people with obesity/overweight, taking Sg into account. It is concluded that, for those with low Sg, SRH can be regarded as a link between snacking and obesity. Prevention of SRH by raising Sg might be key to controlling snacking habits and body weight.

Lower Glucose Effectiveness Is Associated with Subclinical Reactive Hypoglycemia, Snacking Habits, and Obesity

The effects of glucose effectiveness, the insulin-independent mechanism of glucose disposal, on hypoglycemia have not yet been fully investigated. Herein, in 50 males without a diagnosis of diabetes mellitus (median age 54 years, body mass index (BMI) ≥ 25), the index of glucose effectiveness (SgIo) was determined by a 75 g oral glucose tolerance test (OGTT), and continuous glucose monitoring (CGM) was performed for 6 days. The minimal glucose levels and the percentages of time below 70 mg/dL (3.9 mmol/L) (TBR70) during CGM were significantly associated with the SgIo tertile category in a biphasic manner. When TBR70 within 24 h after OGTT ≥ 0.6% was defined as subclinical reactive hypoglycemia (SRH), odds ratios of having SRH in SgIo tertile 1 (lowest) and tertile 3 (highest) compared to SgIo tertile 2 (middle) were both 11.7 (p = 0.007), while the odds ratios of the highest post-load insulin quartile were 22.9 (p = 0.001) and 1.07 (p = 0.742), respectively. The chances of having self-reported snacking habits, obesity (BMI ≥ 30), and impaired glucose tolerance were significantly higher in participants in SgIo tertile 1 compared to those in SgIo tertile 2, with odds ratios of 10.7 (p = 0.005), 11.2 (p = 0.02), and 13.8 (p = 0.002), respectively. However, there was no significant difference between SgIo tertile categories 2 and 3. In conclusion, SgIo is associated with SRH in a biphasic manner. In people with lower glucose effectiveness, the SRH-induced increase in appetite may create a vicious cycle that leads to obesity.

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.

Glucose Effectiveness Decreases in Relationship to a Subtle Worsening of Metabolic Parameters in Young Japanese with Normal Glucose Tolerance

Background: The aim of the study was to investigate the relationship between glucose effectiveness (Sg) and some metabolic parameters in male and female young Japanese. Methods: We measured plasma glucose and immunoreactive insulin levels in 1309 young Japanese persons (age <40 years) with normal glucose tolerance (NGT) before and at 30, 60, and 120 min during a 75 gram oral glucose tolerance test. We also measured serum adiponectin and high-sensitivity C-reactive protein (hsCRP) levels and oral glucose effectiveness (SgI_O), and investigated factors related to SgI_O. Results: The results of Spearman correlation analysis revealed that high-density lipoprotein cholesterol (HDL) and adiponectin were positively correlated with SgI_O, whereas the proportion of males, body mass index, waist circumference (WC), systolic blood pressure (SBP), diastolic blood pressure, triglycerides (TG), and hsCRP were inversely correlated with SgI_O. The results of multiple regression analysis indicated negative correlations between SgI_O and the proportion of males, WC, and SBP and a positive correlation with HDL. The results of multiple regression analysis excluding WC indicated negative correlations between SgI_O and the proportion of males, SBP, and TG and positive correlations with HDL and adiponectin. Conclusions: Sg decreased with a subtle worsening of metabolic parameters, even in young persons with NGT. Decreased Sg may be involved in the development of glucose intolerance in individuals with worse metabolic parameters.

Decrease of FGF19 contributes to the increase of fasting glucose in human in an insulin-independent manner

PURPOSE

The ileum-derived fibroblast growth factor 19 (FGF19) plays key roles in hepatic glucose homeostasis in animals in an insulin-independent manner. Here, we analyzed the association of FGF19 with glucose effectiveness (GE, the insulin-independent glucose regulation), as well as hepatic glucose production (HGP) in Chinese subjects.

METHODS

GE was measured by frequently sampled intravenous glucose tolerance test (FSIVGTT) in normal glucose tolerance (NGT), isolated-impaired glucose tolerance (I-IGT), and isolated-impaired fasting glucose (I-IFG) subjects. The oral glucose tolerance test-derived surrogate of GE (oGE) was determined in NGT, I-IFG, combined glucose intolerance (CGI), and type 2 diabetes (T2DM) subjects. HGP was assessed by labeled ([3-³H]-glucose) hyperinsulinemic-euglycemic clamp in NGT subjects. Insulin secretion and sensitivity were calculated by the hyperglycemic and hyperinsulinemic-euglycemic clamps in a subgroup of NGT, I-IGT, and I-IFG subjects. Serum FGF19 levels were determined by ELISA.

RESULTS

FGF19 positively correlated with GE (r = 0.29, P = 0.004) as determined by FSIVGTT. The result was further confirmed by oGE (r = 0.261, P < 0.001). FGF19 was negatively associated with FPG (r = - 0.228, P = 0.025), but the association no longer existed after adjusting for GE (r = - 0.177, P = 0.086). FGF19 was negatively associated with basal HGP (r = - 0.697, P = 0.006). However, the correlation between FGF19 and insulin secretion and sensitivity were not found.

CONCLUSIONS

FGF19 levels are associated positively with GE and negatively with HGP. The increase of FPG in human is at least partially due to the decrease of FGF19 in an insulin-independent manner.

Oral glucose effectiveness and metabolic risk in obese children and adolescents

AIM

To investigate whether GE is affected in children/adolescents with obesity and abnormalities of the metabolic syndrome (MetS).

METHODS

Cross-sectional study of oral GE (oGE), insulin sensitivity and secretion (calculated on 5 time-points oral glucose tolerance test) and metabolic abnormalities in 1012 patients with overweight/obesity (aged 6.0-17.9 years old). A MetS risk score was calculated on the basis of distribution of fasting glucose, triglycerides, HDL-cholesterol, total cholesterol, systolic and diastolic blood pressure. Non-alcoholic fatty liver disease (NAFLD) was suspected based on thresholds of alanine aminotransferases.

RESULTS

Four-hundred and eighty patients (47.73%) had low-MetS risk score, 488 medium (48.22% with 1-2 risk factors) and 41 (4.05% with ≥ 3 factors) high risk. oGE was significantly lower in subjects with obesity [3.81 (1.46) mg/dl/min^- 1] than in those with overweight [4.98 (1.66) mg/dl/min^- 1; p value < 0.001]. oGE was negatively correlated with BMI (ρ = - 0.79; p < 0.001) and BMI z score (ρ = - 0.56; p < 0.001) and decreased significantly among MetS risk classes (p = 0.001). The median difference of oGE from low to medium risk was estimated to be as - 4.9%, from medium to high as - 13.38% and from low to high as - 17.62%. oGE was not statistically different between NAFLD+ and NAFLD- cases.

CONCLUSIONS

In children and adolescents with obesity oGE decreases. Noteworthy, it decreases as the Met score increases. Therefore, reduced oGE may contribute to the higher risk of these individuals to develop type 2 diabetes.

Effects of growth hormone on hepatic insulin sensitivity and glucose effectiveness in healthy older adults

PURPOSE

Growth hormone (GH) replacement decreases insulin sensitivity in healthy individuals. However, the effects of GH on organ-specific insulin sensitivity and glucose effectiveness are not well characterized. The purpose of this study was to evaluate the effects of GH administration for 26 weeks on muscle and hepatic insulin sensitivity and glucose effectiveness in healthy older individuals.

METHODS

This report is from a 26-week randomized, double-blind, placebo-controlled parallel-group trial in healthy, ambulatory, community-dwelling older women and men. We compared surrogate indices of insulin sensitivity [quantitative insulin-sensitivity check index (QUICKI), muscle insulin sensitivity index (MISI), hepatic insulin resistance index (HIRI)] and glucose effectiveness [oral glucose effectiveness index (oGE)] derived from oral glucose tolerance tests (OGTTs) in subjects before and after 26 weeks of administration of GH (n = 17) or placebo (n = 15) as an exploratory outcome.

RESULTS

GH administration for 26 weeks significantly increased fasting insulin concentrations and HIRI but did not significantly change MISI or oGE compared to placebo.

CONCLUSIONS

GH administration for 26 weeks in healthy older subjects impairs insulin sensitivity in the liver but not skeletal muscle and does not alter glucose effectiveness.

Exercise-induced improvements in glucose effectiveness are blunted by a high glycemic diet in adults with prediabetes

AIMS

Glucose effectiveness (GE) refers to the ability of glucose to influence its own metabolism through insulin-independent mechanisms. Diminished GE is a predictor of progression to type 2 diabetes. Exercise training improves GE, however, little is known about how dietary interventions, such as manipulating the glycemic index of diets, interact with exercise-induced improvements in GE in at-risk populations.

METHODS

We enrolled 33 adults with obesity and pre-diabetes (17 males, 65.7 ± 4.3 years, 34.9 ± 4.2 kg m^-2) into a 12-week exercise training program (1 h day^-1 and 5 day week^-1 at ~ 85% of maximum heart rate) while being randomized to concurrently receive either a low (EX-LOG: 40 ± 0.3 au) or high (EX-HIG: 80 ± 0.6 au) glycemic index diet. A 75-g oral-glucose-tolerance test (OGTT) was performed before and after the intervention and GE was calculated using the Nagasaka equation. Insulin resistance was estimated using a hyperinsulinemic-euglycemic clamp and cardiorespiratory fitness using a VO_2max test.

RESULTS

Both EX-LOG and EX-HIG groups had similar improvements in weight (8.6 ± 5.1 kg, P < 0.001), VO_2max (6 ± 3.5 mL kg^-1 min^-1, P < 0.001) and clamp-measured peripheral insulin resistance (1.7 ± 0.9 mg kg^-1 min^-1, P < 0.001), relative to baseline data. GE in EX-LOG and EX-HIG was similar at baseline (1.9 ± 0.38 vs. 1.85 ± 0.3 mg dL^-1 min^-1, respectively; P > 0.05) and increased by ~ 20% post-intervention in the EX-LOG arm (∆GE: 0.07-0.57 mg dL^-1 min^-1, P < 0.05). Plasma free fatty acid (FFA) concentrations also decreased only in the EX-LOG arm (∆FFA: 0.13 ± 0.23 mmol L^-1, P < 0.05).

CONCLUSIONS

Our data suggest that a high glycemic index diet may suppress exercise-induced enhancement of GE, and this may be mediated through plasma FFAs.

Assessing the predictive accuracy of oral glucose effectiveness index using a calibration model

PURPOSE

Current reference methods for measuring glucose effectiveness (GE) are the somatostatin pancreatic glucose clamp and minimal model analysis of frequently sampled intravenous glucose tolerance test (FSIVGTT), both of which are laborious and not feasible in large epidemiological studies. Consequently, surrogate indices derived from an oral glucose tolerance test (OGTT) to measure GE (oGE) have been proposed and used in many studies. However, the predictive accuracy of these surrogates has not been formally validated. In this study, we used a calibration model analysis to evaluate the accuracy of surrogate indices to predict GE from the reference FSIVGTT (Sg_MM).

METHODS

Subjects (n = 123, mean age 48 ± 11 years; BMI 35.9 ± 7.3 kg/m²) with varying glucose tolerance (NGT, n = 37; IFG/IGT, n = 78; and T2DM, n = 8) underwent FSIVGTT and OGTT on two separate days. Predictive accuracy was assessed by both root mean squared error (RMSE) of prediction and leave-one-out cross-validation-type RMSE of prediction (CVPE).

RESULTS

As expected, insulin sensitivity, Sg_MM, and oGE were reduced in subjects with T2DM and IFG/IGT when compared with NGT. Simple linear regression analyses revealed a modest but significant relationship between oGE and Sg_MM (r = 0.25, p < 0.001). However, using calibration model, measured Sg_MM and predicted Sg_MM derived from oGE were modestly correlated (r = 0.21, p < 0.05) with the best fit line suggesting poor predictive accuracy. There were no significant differences in CVPE and RMSE among the surrogates, suggesting similar predictive ability.

CONCLUSIONS

Although OGTT-derived surrogate indices of GE are convenient and feasible, they have limited ability to robustly predict GE.

An International Consortium Update: Pathophysiology, Diagnosis, and Treatment of Polycystic Ovarian Syndrome in Adolescence

This paper represents an international collaboration of paediatric endocrine and other societies (listed in the Appendix) under the International Consortium of Paediatric Endocrinology (ICPE) aiming to improve worldwide care of adolescent girls with polycystic ovary syndrome (PCOS)1. The manuscript examines pathophysiology and guidelines for the diagnosis and management of PCOS during adolescence. The complex pathophysiology of PCOS involves the interaction of genetic and epigenetic changes, primary ovarian abnormalities, neuroendocrine alterations, and endocrine and metabolic modifiers such as anti-Müllerian hormone, hyperinsulinemia, insulin resistance, adiposity, and adiponectin levels. Appropriate diagnosis of adolescent PCOS should include adequate and careful evaluation of symptoms, such as hirsutism, severe acne, and menstrual irregularities 2 years beyond menarche, and elevated androgen levels. Polycystic ovarian morphology on ultrasound without hyperandrogenism or menstrual irregularities should not be used to diagnose adolescent PCOS. Hyperinsulinemia, insulin resistance, and obesity may be present in adolescents with PCOS, but are not considered to be diagnostic criteria. Treatment of adolescent PCOS should include lifestyle intervention, local therapies, and medications. Insulin sensitizers like metformin and oral contraceptive pills provide short-term benefits on PCOS symptoms. There are limited data on anti-androgens and combined therapies showing additive/synergistic actions for adolescents. Reproductive aspects and transition should be taken into account when managing adolescents.

Effects of Interrupting Sedentary Behavior With Short Bouts of Moderate Physical Activity on Glucose Tolerance in Children With Overweight and Obesity: A Randomized Crossover Trial

OBJECTIVE

Sedentary children have greater risk of developing abnormalities in glucose homeostasis. We investigated whether interrupting sedentary behavior (sitting) with very short periods of walking would improve glucose metabolism without affecting dietary intake in children with overweight or obesity. We hypothesized that interrupting sitting with short bouts of moderate-intensity walking would decrease insulin area under the curve (AUC) during an oral glucose tolerance test (OGTT) compared with uninterrupted sitting.

RESEARCH DESIGN AND METHODS

Overweight/obese (BMI ≥85th percentile) children 7-11 years of age underwent two experimental conditions in random order: prolonged sitting (3 h of continuous sitting) and interrupted sitting (3 min of moderate-intensity walking at 80% of ventilatory threshold every 30 min for 3 h). Insulin, C-peptide, and glucose were measured every 30 min for 3 h during an OGTT. Each session was followed by a buffet meal. Primary outcomes were differences in OGTT hormones and substrates and in buffet meal intake by condition.

RESULTS

Among 35 children with complete data, mixed-model results identified lower insulin and C-peptide in the interrupted condition (P = 0.007 and P = 0.029, respectively); the intervention reduced insulin AUC by 21% (P < 0.001) and C-peptide AUC 18% (P = 0.001) and improved estimated insulin sensitivity (P = 0.013). Neither buffet total energy intake (1,262 ± 480 vs. 1,260 ± 475 kcal; P = 0.89) nor macronutrient composition of the meal (P values >0.38) differed between conditions significantly.

CONCLUSIONS

Interrupting sitting with brief moderate-intensity walking improved glucose metabolism without significantly increasing energy intake in children with overweight or obesity. Interrupting sedentary behavior may be a promising intervention strategy for reducing metabolic risk in such children.

Alterations in Glucose Effectiveness and Insulin Dynamics: Polycystic Ovary Syndrome or Body Mass Index

BACKGROUND/AIMS

To delineate the relationship of polycystic ovary syndrome (PCOS), obesity, and hyperandrogenism (HA) with glucose and insulin dynamics in adolescents across a broad body mass index (BMI).

METHODS

Seventy-four PCOS subjects (aged 16 years) and 82 controls (aged 16 years) were evaluated by an oral glucose tolerance test. Subjects were categorized by BMI: normal weight (21 ± 0.4), overweight/obesity (OO; 33 ± 1.0), and severe obesity (SO; 48 ± 1.4). Indices of glucose and insulin dynamics were determined. Multiple linear regression analysis was used to evaluate the contribution of PCOS, HA, and BMI to these indices.

RESULTS

BMI was significantly associated with systolic and diastolic blood pressure and insulin resistance. A significant interaction between BMI and PCOS and indices of post-glucose load was observed. The mean difference in peak glucose, early glucose response, area under the curve for glucose, and glucose effectiveness (SgIo) between PCOS and control subjects was significantly different between OO and SO. In PCOS subjects, testosterone was positively associated with BMI, fasting insulin, early insulin response, and diastolic blood pressure, and negatively associated with SgIo.

CONCLUSIONS

Abnormal glucose dynamics in adolescents with PCOS is mainly due to SO. The combination of PCOS and SO has a synergistic effect on glucose dynamics when compared to all other groups.

The oral disposition index is a strong predictor of incident diabetes in Asian Indian prediabetic men

AIMS

In this analysis, we sought to examine the prospective association of the disposition index (DIo) derived from oral glucose tolerance test with incident diabetes in Asian Indian men with impaired glucose tolerance (IGT).

METHODS

These post hoc analyses used data from a 2-year prospective study in primary prevention of diabetes using lifestyle intervention among 517 men with IGT. All the participants received standard lifestyle advice at baseline. The surrogate insulin sensitivity and insulin secretion measures were tested for their hyperbolic relationship. Predictive associations of various surrogate measures with incident diabetes were determined using receiver operating characteristic curves.

RESULTS

The combination of total area under the curve of insulin-to-glucose ratio (AUCinsulin/glucose) and Matsuda's insulin sensitivity index was the best equation to depict DIo [β: -0.954 (95 % CI -1.015 to -0.893)] compared to other measures tested in this cohort. There was an inverse association between change in DIo at the final follow-up and development of incident diabetes. Among the surrogate insulin measures studied, DIo [AUC (0.717 (95 % CI 0.675-0.756))] as a composite measure was superior than other surrogate indices.

CONCLUSIONS

Among the surrogate indices studied, DIo was the best measure associated with incident diabetes.

Glucose effectiveness in obese children: relation to degree of obesity and dysglycemia

OBJECTIVE

Impaired glucose effectiveness (GE) plays a role in the deterioration of glucose metabolism. Our aim was to validate a surrogate of GE derived from an oral glucose tolerance test (OGTT) and to assess the impact of degrees of obesity and of glucose tolerance on it.

RESEARCH DESIGN AND METHODS

The OGTT-derived surrogate of GE (oGE) was validated in obese adolescents who underwent an OGTT and an intravenous glucose tolerance test (IVGTT). We then evaluated anthropometric determinants of the oGE and its impact on the dynamics of glucose tolerance in a cohort of children with varying degrees of obesity.

RESULTS

The correlation of oGE and IVGTT-derived GE in 98 obese adolescents was r = 0.35 (P < 0.001) as a whole and r = 0.51 (P < 0.001) in subjects with normal glucose tolerance. In a cohort of 1,418 children, the adjusted GE was associated with increasing obesity (P < 0.001 for each category of obesity). Quartiles of oGE and the oral disposition index were associated with 2-h glucose levels (P < 0.001 for both). Among 421 nondiabetic obese subjects (276 subjects with normal glucose tolerance/145 subjects with impaired glucose tolerance who repeated their OGTT after a mean time of 28 ± 16 months), oGE changes were tightly associated with weight (r = 0.83, P < 0.001) and waist circumference changes (r = 0.67, P < 0.001). Baseline oGE and changes in oGE over time emerged as significant predictors of the change in 2-h glucose levels (standardized B = -0.76 and B = -0.98 respectively, P < 0.001 for both).

CONCLUSIONS

The oGE is associated with the degree of and changes in weight and waist circumference and is an independent predictor of glucose tolerance dynamics.

Longitudinal changes in insulin sensitivity, insulin secretion, beta cell function and glucose effectiveness during development of non-diabetic hyperglycemia in a Japanese population

Since there had been no previous studies of alterations in insulin sensitivity, glucose-stimulated insulin secretion, beta cell function and glucose effectiveness during the development of non-diabetic hyperglycemia in Asian populations, we conducted a longitudinal study of such changes in 244 Japanese adults with normal glucose tolerance (median BMI 23.3 kg/m² and age 51 yrs). The median follow-up period was 3.3 yrs. One hundred and eighty-two subjects maintained normal glucose tolerance (nonprogressors). After excluding the 3 subjects who progressed to diabetes, we analyzed the 59 who developed non-diabetic hyperglycemia (progressors), of which 31 progressed to impaired fasting glucose and 28 to impaired glucose tolerance. Whole body insulin sensitivity was estimated by ISI_Matsuda, glucose-stimulated insulin secretion by [δIRI_0-30/δPG_0-30] and Stumvoll indices, hepatic insulin sensitivity by quantitative insulin sensitivity check index (QUICKI) and 1/fasting IRI, beta cell function by oral disposition index (DI_O) ([δIRI_0-30/δPG_0-30]∙[ISI_Matsuda]), and glucose effectiveness by an OGTT-derived index (SgI_O). ISI_Matsuda (p <0.05), [δIRI_0-30/δPG_0-30], DI_O and SgI_O (both p <0.01), but not QUICKI, 1/fasting IRI, or Stumvoll-1st and -2nd phases, were lower in the progressors at baseline. This group was also characterized by the following: 1) ISI_Matsuda, DI_O and SgI_O were reduced by 34%, 32% and 11%, respectively (all p <0.01); 2) QUICKI and 1/fasting IRI diminished by 21% and 5%, respectively (both p <0.01); and 3) no significant changes were found in [δIRI_0-30/δPG_0-30], Stumvoll-1st and -2nd phases or BMI during the follow-up. In the nonprogressors, no indices changed significantly during the follow-up. Our study concluded that during the transition from normal glucose tolerance to non-diabetic hyperglycemia in this non-obese population, whole body insulin sensitivity, hepatic insulin sensitivity, beta cell function, and glucose effectiveness were all attenuated, but no significant changes in glucose-stimulated insulin secretion occurred. Also of note is the fact that the transition took place without any accompanying increase in BMI.