Insulin sensitivity, β-cell function, and incretin effect in individuals with elevated 1-hour postload plasma glucose levels

The incretin effect in type 2 diabetes in a Sub-Saharan African population

AIM

Type 2 diabetes is increasing in Sub-Saharan Africa, but the pathophysiology in this population is poorly investigated. In Western populations, the incretin effect is reduced in type 2 diabetes, leading to lowered insulin secretion. The aim of this study was to investigate the incretin effect in a group of Sub-Saharan Africans with type 2 diabetes.

METHODS

Twenty adults diagnosed with type 2 diabetes, based on either an oral glucose tolerance test (n = 10) or on glycated hemoglobin A1c (n = 10), and 10 non-diabetic controls were included in an interventional study in Tanzania. We investigated the incretin effect as the difference between the plasma insulin area under the curve during an oral glucose tolerance test and that obtained during an intravenous glucose infusion. Differences between diabetes groups were analyzed by Kruskal-Wallis one-way analysis of variance.

RESULTS

The incretin effect did not differ between groups (p = 0.45), and there was no difference in plasma concentrations of the incretin hormones during the OGTT.

CONCLUSION

A reduced incretin effect appears not to contribute to hyperglycemia in type 2 diabetes in this Tanzanian population. More research is needed to explain the diabetes phenotype often seen in Sub-Saharan Africa.

TRIAL REGISTRATION

Clinicaltrials.gov: NCT03106480 , date of registration: 04/10/2017.

Contribution of Insulin Resistance and β Cell Dysfunction to Gestational Diabetes Stratified for Pre-pregnant Body Mass Index

The objective of the study was to evaluate the contribution of insulin resistance and β cell dysfunction to gestational diabetes mellitus (GDM) in Chinese women stratified by pre-pregnant body mass index (BMI). A total of 847 pregnant women were enrolled. They were divided into low BMI and high BMI groups according to the median of pre-pregnancy BMI. The homeostasis model assessment of insulin resistance (HOMA-IR) and β cell function (HOMA-β), Matsuda index, and 60-min insulinogenic index (IGI60) were used to evaluate insulin resistance and β cell function. In all the participants, 150 (17.71%) were diagnosed with GDM. ROC analyses showed that in the low BMI group, the association of β cell dysfunction (IGI60 or HOMA-β) with GDM was stronger than that of insulin resistance (Matsuda index or HOMA-IR), while in the high BMI group, the association of β cell dysfunction with GDM was weaker than that of insulin resistance (all P < 0.05). Among all GDM patients, 47.33% demonstrated predominant insulin resistance (Matsuda index < 25th percentile), and 46% had predominant β cell defect (IGI60 < 25th percentile). In the low BMI group, 15.09% of GDM patients demonstrated predominant insulin resistance, and 62.26% of GDM patients had predominant β cell defect, whereas in the high BMI group, 64.95% of GDM patients demonstrated mainly insulin resistance and 36.08% of GDM patients had mainly β cell defect. In women with low BMI, β cell dysfunction is the major etiologic factor, whereas, in women with high BMI, insulin resistance is the predominant etiologic factor in the development of GDM.

International Diabetes Federation Position Statement on the 1-hour post-load plasma glucose for the diagnosis of intermediate hyperglycaemia and type 2 diabetes

Many individuals with intermediate hyperglycaemia (IH), including impaired fasting glycaemia (IFG) and impaired glucose tolerance (IGT), as presently defined, will progress to type 2 diabetes (T2D). There is confirmatory evidence that T2D can be prevented by lifestyle modification and/or medications, in people with IGT diagnosed by 2-h plasma glucose (PG) during a 75-gram oral glucose tolerance test (OGTT). Over the last 40 years, a wealth of epidemiological data has confirmed the superior value of 1-h plasma glucose (PG) over fasting PG (FPG), glycated haemoglobin (HbA1c) and 2-h PG in populations of different ethnicity, sex and age in predicting diabetes and associated complications including death. Given the relentlessly rising prevalence of diabetes, a more sensitive, practical method is needed to detect people with IH and T2D for early prevention or treatment in the often lengthy trajectory to T2D and its complications. The International Diabetes Federation (IDF) Position Statement reviews findings that the 1-h post-load PG ≥ 155 mg/dL (8.6 mmol/L) in people with normal glucose tolerance (NGT) during an OGTT is highly predictive for detecting progression to T2D, micro- and macrovascular complications, obstructive sleep apnoea, cystic fibrosis-related diabetes mellitus, metabolic dysfunction-associated steatotic liver disease, and mortality in individuals with risk factors. The 1-h PG of 209 mg/dL (11.6 mmol/L) is also diagnostic of T2D. Importantly, the 1-h PG cut points for diagnosing IH and T2D can be detected earlier than the recommended 2-h PG thresholds. Taken together, the 1-h PG provides an opportunity to avoid misclassification of glycaemic status if FPG or HbA1c alone are used. The 1-h PG also allows early detection of high-risk people for intervention to prevent progression to T2D which will benefit the sizeable and growing population of individuals at increased risk of T2D. Using a 1-h OGTT, subsequent to screening with a non-laboratory diabetes risk tool, and intervening early will favourably impact the global diabetes epidemic. Health services should consider developing a policy for screening for IH based on local human and technical resources. People with a 1-h PG ≥ 155 mg/dL (8.6 mmol/L) are considered to have IH and should be prescribed lifestyle intervention and referred to a diabetes prevention program. People with a 1-h PG ≥ 209 mg/dL (11.6 mmol/L) are considered to have T2D and should have a repeat test to confirm the diagnosis of T2D and then referred for further evaluation and treatment. The substantive data presented in the Position Statement provides strong evidence for redefining current diagnostic criteria for IH and T2D by adding the 1-h PG.

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.

Impaired insulin-stimulated myocardial glucose metabolic rate is associated with reduced estimated myocardial energetic efficiency in subjects with different degrees of glucose tolerance

BACKGROUND

Alterations in myocardial mechano-energetic efficiency (MEEi), which represents the capability of the left ventricles to convert the chemical energy obtained by oxidative metabolism into mechanical work, have been associated with cardiovascular disease. Although whole-body insulin resistance has been related to impaired myocardial MEEi, it is unknown the relationship between cardiac insulin resistance and MEEi. Aim of this study was to evaluate the relationship between insulin-stimulated myocardial glucose metabolic rate (MrGlu) and myocardial MEEi in subjects having different degrees of glucose tolerance.

METHODS

We evaluated insulin-stimulated myocardial MrGlu using cardiac dynamic positron emission tomography (PET) with 18F-Fluorodeoxyglucose (18F-FDG) combined with euglycemic-hyperinsulinemic clamp, and myocardial MEEi in 57 individuals without history of coronary heart disease having different degrees of glucose tolerance. The subjects were stratified into tertiles according to their myocardial MrGlu values.

RESULTS

After adjusting for age, gender and BMI, subjects in I tertile showed a decrease in myocardial MEEi (0.31 ± 0.05 vs 0.42 ± 0.14 ml/s*g, P = 0.02), and an increase in myocardial oxygen consumption (MVO2) (10,153 ± 1375 vs 7816 ± 1229 mmHg*bpm, P < 0.0001) as compared with subjects in III tertile. Univariate correlations showed that insulin-stimulated myocardial MrGlu was positively correlated with MEEi and whole-body glucose disposal, and negatively correlated with waist circumference, fasting plasma glucose, HbA1c and MVO2. In a multivariate regression analysis running a model including several CV risk factors, the only variable that remained significantly associated with MEEi was myocardial MrGlu (β 0.346; P = 0.01).

CONCLUSIONS

These data suggest that an impairment in insulin-stimulated myocardial glucose metabolism is an independent contributor of depressed myocardial MEEi in subjects without history of CHD.

The Triglycerides and Glucose (TyG) Index Is Associated with 1-Hour Glucose Levels during an OGTT

BACKGROUND AND OBJECTIVES

Among individuals with normal glucose tolerance (NGT), subjects with high levels of plasma glucose (≥155 mg/dL) at sixty minutes during an oral glucose tolerance test (1h-OGTT) are at an increased risk of developing type 2 diabetes. We investigated the association between the triglycerides and glucose (TyG) index, a novel marker of insulin resistance, with 1h-OGTT glucose plasma concentrations.

MATERIAL AND METHODS

1474 non-diabetic Caucasian subjects underwent a 75 g OGTT and were divided into two groups according to the cutoff 1h-OGTT plasma glucose < 155 mg/dL (NGT-1h-low) and ≥ 155 mg/dL (NGT-1h-high). The TyG index was calculated as ln [fasting triglycerides (milligrams per deciliter) × fasting blood glucose (milligrams per deciliter)/2]. Multivariable linear and logistic regression analyses were used to establish the contribution of the TyG index to the variability of 1h-OGTT glucose, and how the former affected the risk of being NGT-1h-high.

RESULTS

1004 individuals were NGT-1h-low and 470 were NGT-1h-high. The TyG index was higher for NGT-1h-high (p = 0.001) individuals, and it was an independent factor influencing 1h-OGTT glycemia (β = 0.191, p < 0.001) after correcting for age, sex, and BMI. The TyG index was the strongest marker associated with the risk of being NGT-1h-high (OR = 1.703, CI 95% 1.34-2.17, p < 0.001) when compared with FPG (OR = 1.054, CI 95% 1.04-1.07, p < 0.001) and the HOMA-IR (OR = 1.156, CI 95% 1.08-1.23, p < 0.001).

CONCLUSIONS

Our study demonstrated that the TyG index, an efficient and cost-effective marker of insulin resistance, is associated with the variability of early post-challenge glucose levels and is an independent marker of being NGT-1h-high.

Sex-differences in insulin sensitivity and insulin secretion in subjects with impaired fasting glucose and impaired glucose tolerance

AIMS

To assess sex-related differences in whole-body insulin sensitivity and insulin secretion in a group of Caucasian subjects with varying degrees of glucose tolerance.

METHODS

Sex-related differences in insulin sensitivity using the hyperinsulinemic-euglycemic clamp technique and insulin secretion using validated indexes obtained during an oral glucose tolerance test were examined among 570 non-diabetic offspring individuals having only one parent with type 2 diabetes. Participants were classified as having with NGT, isolated impaired fasting glucose (IFG), isolated impaired glucose tolerance (IGT) and combined IFG/IGT.

RESULTS

Isolated IFG, isolated IGT, and combined IFG/IGT women exhibited greater relative differences in BMI, waist circumference, and insulin-stimulated glucose disposal than their male counterparts. Formal tests for glucose tolerance status × sex interaction were statistically significant for BMI (P = 0.05) waist circumference (P = 0.04), and insulin-stimulated glucose disposal (P = 0.01) suggesting a sex-specific association. By contrast, tests for glucose tolerance status × sex interaction regarding both insulinogenic and disposition indexes were not significant.

CONCLUSIONS

This study suggests that deterioration of glucose homeostasis in women is associated with a greater fat accumulation and worsening in insulin sensitivity as compared with men.

One-hour plasma glucose as a long-term predictor of cardiovascular events and all-cause mortality in a Chinese older male population without diabetes: A 20-year retrospective and prospective study

Introduction

Elevated one-hour plasma glucose (1 h-PG) during oral glucose tolerance test predicts the development of type 2 diabetes mellitus and its complications. However, to date, there have been no studies investigating the predictive values of 1 h-PG for the risk of cardiovascular diseases (CVDs) and all-cause mortality in the elderly population in China. This study aimed to evaluate and compare the effectiveness of 1 h-PG and two-hour plasma glucose (2 h-PG) to predict the risk of CVD and all-cause mortality in the Chinese elderly population.

Materials and methods

This retrospective and prospective cohort study was conducted using data obtained from the Chinese People’s Liberation Army General Hospital. All the non-diabetic elderly participants, who had plasma glucose measured at 0, 1, and 2 h during an OGTT (75 g glucose), were followed for 20 years. The primary outcomes were all-cause mortality, myocardial infarction, unstable angina, and stroke. Multivariate-adjusted Cox proportional hazard regression models were performed to examine the association between risk factors and outcomes and to estimate the risk of CVD and all-cause mortality based on 1 h-PG levels.

Results

A total of 862 non-diabetic male individuals were included. The median age was 74.0 (25th–75th percentile: 68.0–79.0) years. There were 480 CVD events and 191 deaths during 15,527 person-years of follow-up. The adjusted hazard ratio (HR) of 1 h-PG as a continuous variable was 1.097 (95% CI 1.027–1.172; P = 0.006) for CVD events and 1.196 (95% CI 1.115–1.281; P < 0.001) for higher risk of mortality. When compared with the lowest 1 h-PG tertile, the other tertiles were associated with CVD events (HR 1.464, 95% CI 1.031–2.080; P = 0.033 and HR 1.538, 95% CI 1.092–2.166; P = 0.014, for tertile 2 and tertile 3 compared with tertile 1, respectively), and the highest 1 h-PG tertile had a significantly higher risk of mortality (HR 2.384, 95% CI 1.631–3.485; P < 0.001) after full adjustment. Compared with 1 h-PG, 2 h-PG had similar abilities to predict all-cause mortality. However, 2 h-PG was less closely associated with CVD when examined in the fully adjusted model, neither as a continuous variable nor as a categorical variable. Conversely, 1 h-PG remained an independent predictor of CVD and all-cause mortality after adjusting for various traditional risk factors.

Conclusion

Patients with higher 1 h-PG had a significantly increased risk of CVD and all-cause mortality regardless of prediabetes status or development of diabetes at follow-up. The 1 h-PG level might be a better predictor of cardiovascular risk than the 2 h-PG level for the Chinese elderly population.

Elevated One-Hour Post-Load Glucose Is Independently Associated with Albuminuria: A Cross-Sectional Population Study

The purpose of this study was to examine and compare the associations between albuminuria and fasting (FPG), 1 h post-load (1 h PG) and 2 h post-load plasma glucose (2 h PG) in an oral glucose tolerance test (OGTT). A total of 496 people free of known diabetes (mean age 72 years) participated in the examinations including the OGTT with plasma glucose measurements at 0, 1, and 2 h and levels of HbA1c. Albuminuria was determined by the urinary albumin-to-creatinine ratio and was defined as ≥3.0 mg/mmol. Compared with those without albuminuria, participants with albuminuria had significantly higher 1 h PG and 2 h PG levels, but not FPG or HbA1c levels. An elevated 1 h PG increased the estimated odds ratio of albuminuria more than three times in people with prediabetic 1 h PG (8.6–11.5 mmol/L: OR 3.60; 95% CI 1.70–7.64) and diabetic 1 h PG (≥11.6 mmol/L: OR 3.05; 95% CI 1.29–7.23). After adjusting for blood pressure and age, the association of elevated 1 h PG with albuminuria remained significant. Prediabetic or diabetic FPG, 2 h PG, or HbA1c did not have a statistically significant association with albuminuria. These findings suggest that 1 h PG seems to be the best glycemic parameter and is useful in recognizing persons with an elevated risk of early kidney disease due to hyperglycemia.

Profiles of Glucose Metabolism in Different Prediabetes Phenotypes, Classified by Fasting Glycemia, 2-Hour OGTT, Glycated Hemoglobin, and 1-Hour OGTT: An IMI DIRECT Study

Differences in glucose metabolism among categories of prediabetes have not been systematically investigated. In this longitudinal study, participants (N = 2,111) underwent a 2-h 75-g oral glucose tolerance test (OGTT) at baseline and 48 months. HbA_1c was also measured. We classified participants as having isolated prediabetes defect (impaired fasting glucose [IFG], impaired glucose tolerance [IGT], or HbA_1c indicative of prediabetes [IA1c]), two defects (IFG+IGT, IFG+IA1c, or IGT+IA1c), or all defects (IFG+IGT+IA1c). β-Cell function (BCF) and insulin sensitivity were assessed from OGTT. At baseline, in pooling of participants with isolated defects, they showed impairment in both BCF and insulin sensitivity compared with healthy control subjects. Pooled groups with two or three defects showed progressive further deterioration. Among groups with isolated defect, those with IGT showed lower insulin sensitivity, insulin secretion at reference glucose (ISR_r), and insulin secretion potentiation (P < 0.002). Conversely, those with IA1c showed higher insulin sensitivity and ISR_r (P < 0.0001). Among groups with two defects, we similarly found differences in both BCF and insulin sensitivity. At 48 months, we found higher type 2 diabetes incidence for progressively increasing number of prediabetes defects (odds ratio >2, P < 0.008). In conclusion, the prediabetes groups showed differences in type/degree of glucometabolic impairment. Compared with the pooled group with isolated defects, those with double or triple defect showed progressive differences in diabetes incidence.

High protein diet leads to prediabetes remission and positive changes in incretins and cardiovascular risk factors

BACKGROUND AND AIMS

High Protein diets may be associated with endocrine responses that favor improved metabolic outcomes. We studied the response to High Protein (HP) versus High Carbohydrate (HC) Diets in terms of incretin hormones GLP-1 and GIP, the hunger hormone ghrelin and BNP, which is associated with cardiac function. We hypothesized that HP diets induce more pronounced release of glucose lowering hormones, suppress hunger and improve cardiac function.

METHODS AND RESULTS

24 obese women and men with prediabetes were recruited and randomized to either a High Protein (HP) (n = 12) or High Carbohydrate (HC) (n = 12) diet for 6 months with all food provided. OGTT and MTT were performed and GLP-1, GIP, Ghrelin, BNP, insulin and glucose were measured at baseline and 6 months on the respective diets. Our studies showed that subjects on the HP diet had 100% remission of prediabetes compared to only 33% on the HC diet with similar weight loss. HP diet subjects had a greater increase in (1) OGTT GLP-1 AUC(p = 0.001) and MTT GLP-1 AUC(p = 0.001), (2) OGTT GIP AUC(p = 0.005) and MTT GIP AUC(p = 0.005), and a greater decrease in OGTT ghrelin AUC(p = 0.005) and MTT ghrelin AUC(p = 0.001) and BNP(p = 0.001) compared to the HC diet at 6 months.

CONCLUSIONS

This study demonstrates that the HP diet increases GLP-1 and GIP which may be responsible in part for improved insulin sensitivity and β cell function compared to the HC diet. HP ghrelin results demonstrate the HP diet can reduce hunger more effectively than the HC diet. BNP and other CVRF, metabolic parameters and oxidative stress are significantly improved compared to the HC diet. CLINICALTRIALS.

GOV IDENTIFIER

NCT01642849.

Hyperglycemia at 1h-OGTT in Pregnancy: A Reliable Predictor of Metabolic Outcomes?

Gestational diabetes mellitus (GDM) is associated with a high risk of developing type 2 diabetes (T2DM) and cardiovascular disease (CVD). Identifying among GDM women those who are at high risk may help prevent T2DM and, possibly CVD. Several studies have shown that in women with GDM, hyperglycemia at 1 h during an oral glucose tolerance test (OGTT) (1-h PG) is not only associated with an increase in adverse maternal and perinatal outcomes but is also an independent predictor of T2DM. Interestingly, also in pregnant women who did not meet the criteria for a GDM diagnosis, 1-h PG was an independent predictor of postpartum impaired insulin sensitivity and beta-cell dysfunction. Moreover, maternal 1- and 2-h PG levels have been found to be independently associated with insulin resistance and impaired insulin secretion also during childhood. There is evidence that hyperglycemia at 1h PG during pregnancy may identify women at high risk of future CVD, due to its association with an unfavorable CV risk profile, inflammation, arterial stiffness and endothelial dysfunction. Overall, hyperglycemia at 1h during an OGTT in pregnancy may be a valuable prediction tool for identifying women at a high risk of future T2DM, who may then benefit from therapeutic strategies aimed at preventing cardiovascular outcomes.

Maternal dysglycaemia, changes in the infant's epigenome modified with a diet and physical activity intervention in pregnancy: Secondary analysis of a randomised control trial

BACKGROUND

Higher maternal plasma glucose (PG) concentrations, even below gestational diabetes mellitus (GDM) thresholds, are associated with adverse offspring outcomes, with DNA methylation proposed as a mediating mechanism. Here, we examined the relationships between maternal dysglycaemia at 24 to 28 weeks' gestation and DNA methylation in neonates and whether a dietary and physical activity intervention in pregnant women with obesity modified the methylation signatures associated with maternal dysglycaemia.

METHODS AND FINDINGS

We investigated 557 women, recruited between 2009 and 2014 from the UK Pregnancies Better Eating and Activity Trial (UPBEAT), a randomised controlled trial (RCT), of a lifestyle intervention (low glycaemic index (GI) diet plus physical activity) in pregnant women with obesity (294 contol, 263 intervention). Between 27 and 28 weeks of pregnancy, participants had an oral glucose (75 g) tolerance test (OGTT), and GDM diagnosis was based on diagnostic criteria recommended by the International Association of Diabetes and Pregnancy Study Groups (IADPSG), with 159 women having a diagnosis of GDM. Cord blood DNA samples from the infants were interrogated for genome-wide DNA methylation levels using the Infinium Human MethylationEPIC BeadChip array. Robust regression was carried out, adjusting for maternal age, smoking, parity, ethnicity, neonate sex, and predicted cell-type composition. Maternal GDM, fasting glucose, 1-h, and 2-h glucose concentrations following an OGTT were associated with 242, 1, 592, and 17 differentially methylated cytosine-phosphate-guanine (dmCpG) sites (false discovery rate (FDR) ≤ 0.05), respectively, in the infant's cord blood DNA. The most significantly GDM-associated CpG was cg03566881 located within the leucine-rich repeat-containing G-protein coupled receptor 6 (LGR6) (FDR = 0.0002). Moreover, we show that the GDM and 1-h glucose-associated methylation signatures in the cord blood of the infant appeared to be attenuated by the dietary and physical activity intervention during pregnancy; in the intervention arm, there were no GDM and two 1-h glucose-associated dmCpGs, whereas in the standard care arm, there were 41 GDM and 160 1-h glucose-associated dmCpGs. A total of 87% of the GDM and 77% of the 1-h glucose-associated dmCpGs had smaller effect sizes in the intervention compared to the standard care arm; the adjusted r2 for the association of LGR6 cg03566881 with GDM was 0.317 (95% confidence interval (CI) 0.012, 0.022) in the standard care and 0.240 (95% CI 0.001, 0.015) in the intervention arm. Limitations included measurement of DNA methylation in cord blood, where the functional significance of such changes are unclear, and because of the strong collinearity between treatment modality and severity of hyperglycaemia, we cannot exclude that treatment-related differences are potential confounders.

CONCLUSIONS

Maternal dysglycaemia was associated with significant changes in the epigenome of the infants. Moreover, we found that the epigenetic impact of a dysglycaemic prenatal maternal environment appeared to be modified by a lifestyle intervention in pregnancy. Further research will be needed to investigate possible medical implications of the findings.

TRIAL REGISTRATION

ISRCTN89971375.

Review of methods for detecting glycemic disorders

Prediabetes (intermediate hyperglycemia) consists of two abnormalities, impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) detected by a standardized 75-gram oral glucose tolerance test (OGTT). Individuals with isolated IGT or combined IFG and IGT have increased risk for developing type 2 diabetes (T2D) and cardiovascular disease (CVD). Diagnosing prediabetes early and accurately is critical in order to refer high-risk individuals for intensive lifestyle modification. However, there is currently no international consensus for diagnosing prediabetes with HbA1c or glucose measurements based upon American Diabetes Association (ADA) and the World Health Organization (WHO) criteria that identify different populations at risk for progressing to diabetes. Various caveats affecting the accuracy of interpreting the HbA1c including genetics complicate this further. This review describes established methods for detecting glucose disorders based upon glucose and HbA1c parameters as well as novel approaches including the 1-hour plasma glucose (1-h PG), glucose challenge test (GCT), shape of the glucose curve, genetics, continuous glucose monitoring (CGM), measures of insulin secretion and sensitivity, metabolomics, and ancillary tools such as fructosamine, glycated albumin (GA), 1,5- anhydroglucitol (1,5-AG). Of the approaches considered, the 1-h PG has considerable potential as a biomarker for detecting glucose disorders if confirmed by additional data including health economic analysis. Whether the 1-h OGTT is superior to genetics and omics in providing greater precision for individualized treatment requires further investigation. These methods will need to demonstrate substantially superiority to simpler tools for detecting glucose disorders to justify their cost and complexity.

Evaluation of the relationship between the one-hour plasma glucose concentration and beta-cell functions and cardiometabolic parameters during oral glucose tolerance test in obese children and adolescents

Background In this study, we aimed to evaluate the relationship between the 1-h plasma glucose (PG) level in the oral glucose tolerance test (OGTT) and conventional glycemic parameters, indices evaluating beta-cell functions, and cardiometabolic risk factors. Methods The records of 532 obese patients who were followed up in the Pediatric Endocrinology Polyclinic and who underwent standard OGTT were evaluated retrospectively. All patients were divided into two groups according to OGTT data as the 1-h plasma glucose concentration <155 mg/dL (n=329) and ≥155 mg/dL (n=203). Patients with normal glucose tolerance (NGT) were divided into two groups according to the 1-h PG level, as 218 patients with NGT 1 h-low (<155 mg/dL) and 53 patients with high NGT 1 h-high (≥155 mg/dL). Results There was a statistically significant difference between the lipid profiles of individuals with NGT 1 h-low (<155 mg/dL) and individuals with NGT 1 h-high (≥155 mg/dL) (p<0.001). Total cholesterol, LDL cholesterol, and triglyceride levels were higher, while HDL cholesterol levels were lower in individuals with NGT 1 h-high (≥155 mg/dL). The indices evaluating beta-cell functions were significantly higher in individuals with NGT 1 h-low (<155 mg/dL). Conclusion As a result, a plasma glucose concentration above or equal to 155 mg/dL at 1 h during an OGTT is associated with a worse clinical phenotype characterized by changes in insulin sensitivity and β-cell function. Therefore, this threshold value can predict the progression of prediabetes in obese young people with NGT.

Reduction in Global Myocardial Glucose Metabolism in Subjects With 1-Hour Postload Hyperglycemia and Impaired Glucose Tolerance

OBJECTIVE

Impaired insulin-stimulated myocardial glucose uptake has occurred in patients with type 2 diabetes with or without coronary artery disease. Whether cardiac insulin resistance is present remains uncertain in subjects at risk for type 2 diabetes, such as individuals with impaired glucose tolerance (IGT) or those with normal glucose tolerance (NGT) and 1-h postload glucose ≥155 mg/dL during an oral glucose tolerance test (NGT 1-h high). This issue was examined in this study.

RESEARCH DESIGN AND METHODS

The myocardial metabolic rate of glucose (MRGlu) was measured by using dynamic ¹⁸F-fluorodeoxyglucose positron emission tomography combined with a euglycemic-hyperinsulinemic clamp in 30 volunteers without coronary artery disease. Three groups were studied: 1) those with 1-h postload glucose <155 mg/dL (NGT 1-h low) (n = 10), 2) those with NGT 1-h high (n = 10), 3) and those with IGT (n = 10).

RESULTS

After adjusting for age, sex, and BMI, both subjects with NGT 1-h high (23.7 ± 6.4 mmol/min/100 mg; P = 0.024) and those with IGT (16.4 ± 6.0 mmol/min/100 mg; P < 0.0001) exhibited a significant reduction in global myocardial MRGlu; this value was 32.8 ± 9.7 mmol/min/100 mg in subjects with NGT 1-h low. Univariate correlations showed that MRGlu was positively correlated with insulin-stimulated whole-body glucose disposal (r = 0.441; P = 0.019) and negatively correlated with 1-h (r = -0.422; P = 0.025) and 2-h (r = -0.374; P = 0.05) postload glucose levels, but not with fasting glucose.

CONCLUSIONS

This study shows that myocardial insulin resistance is an early defect that is already detectable in individuals with dysglycemic conditions associated with an increased risk of type 2 diabetes, such as IGT and NGT 1-h high.

Metabolic characteristics of Africans with normal glucose tolerance and elevated 1-hour glucose: insight from the Africans in America study

INTRODUCTION

Risk of insulin resistance, dyslipidemia, diabetes and cardiac death is increased in Asians and Europeans with normal glucose tolerance (NGT) and 1-hour glucose ≥8.6 mmol/L. As African descent populations often have insulin resistance but a normal lipid profile, the implications for Africans with NGT and glucose ≥8.6 mmol/L (NGT-1-hour-high) are unknown.

OBJECTIVE

We performed oral glucose tolerance tests (OGTTs) in 434 African born-blacks living in Washington, DC (male: 66%, age 38±10 years (mean±SD)) and determined in the NGT group if either glucometabolic or lipid profiles varied according to a 1-hour-glucose threshold of 8.6 mmol/L.

METHODS

Glucose tolerance category was defined by OGTT criteria. NGT was subdivided into NGT-1-hour-high (glucose ≥8.6 mmol/L) and NGT-1-hour-normal (glucose <8.6 mmol/L). Second OGTT were performed in 27% (119/434) of participants 10±7 days after the first. Matsuda Index and Oral Disposition Index measured insulin resistance and beta-cell function, respectively. Lipid profiles were obtained. Comparisons were by one-way analysis of variance with Bonferonni corrections for multiple comparisons. Duplicate tests were assessed by к-statistic.

RESULTS

One-hour-glucose ≥8.6 mmol/L occurred in 17% (47/272) with NGT, 72% (97/134) with pre-diabetes and in 96% (27/28) with diabetes. Both insulin resistance and beta-cell function were worse in NGT-1-hour-high than in NGT-1-hour-normal. Dyslipidemia occurred in both the diabetes and pre-diabetes groups but not in either NGT group. One-hour glucose concentration ≥8.6 mmol/L showed substantial agreement for the two OGTTs (к=0.628).

CONCLUSIONS

Although dyslipidemia did not occur in either NGT group, insulin resistance and beta-cell compromise were worse in NGT-1 hour-high. Subdividing the NGT group at a 1-hour glucose threshold of 8.6 mmol/L may stratify risk for diabetes in Africans.

Plasma glucose concentration 60 min post oral glucose load and risk of type 2 diabetes and cardiovascular disease: Pathophysiological implications

AIM

The aim of this study was to gain insight into the pathophysiological significance of elevated plasma glucose concentrations (mmol/L) 60 min post oral glucose load in apparently healthy individuals.

METHODS

Comparison of resistance to insulin action and associated cardio-metabolic risk factors in 490 apparently healthy persons, subdivided into those with a plasma glucose concentration 60 min following a 75-g oral glucose challenge of <8.6 versus ⩾8.6.

RESULTS

Insulin resistance was significantly greater in persons with normal glucose tolerance whose 60-min glucose concentration was ⩾8.6, associated with higher blood pressure, plasma concentrations of glucose, insulin, triglyceride and lower high-density lipoprotein cholesterol concentrations. Similar differences were seen in persons with impaired fasting glucose, but not in those with impaired glucose tolerance or both impaired fasting glucose and impaired glucose tolerance. The group whose 60-min glucose was <8.6 (n = 318) contained primarily persons with normal glucose tolerance (88%), whereas the majority of those whose 60-min value was ⩾8.6 (n = 172) had prediabetes (59%) and in particular combined impaired fasting glucose and impaired glucose tolerance.

CONCLUSION

Plasma glucose concentration of ⩾8.6 mmol/L 60 min post oral glucose identifies higher proportions of combined impaired fasting glucose and impaired glucose tolerance individuals as well as normal glucose tolerance and impaired fasting glucose individuals with a more adverse cardio-metabolic profile, contributing to observed increased overall risk of type 2 diabetes and other metabolic diseases.

Intestinal Glucose Absorption Is a Key Determinant of 1-Hour Postload Plasma Glucose Levels in Nondiabetic Subjects

CONTEXT

One-hour postload hyperglycemia, defined as 1-hour plasma glucose (1hPG) ≥ 155 mg/dL during an oral glucose tolerance test (OGTT), has been proposed as an independent predictor of type 2 diabetes. Recent evidence suggests that 1-hour hyperglycemia can be explained by enhanced duodenal glucose absorption, which in turn may increase the rate of appearance of oral glucose in the systemic circulation (RaO). However, the impact of RaO on 1hPG and 1-hour glucose excursions (incremental area under the curve calculated through the first hour after glucose ingestion; glucose iAUC1h) is still unknown.

OBJECTIVE

We quantified the relative contribution of postload RaO to 1hPG and glucose iAUC1h with respect to other major glucose homeostatic mechanisms in nondiabetic participants.

PARTICIPANTS AND METHODS

Model-derived β-cell function, insulin clearance, glucose metabolic fluxes, and peripheral and hepatic insulin sensitivity were measured during a 75-g OGTT by a double tracer method in 23 nondiabetic volunteers.

RESULTS

Early insulin secretion, whole-body insulin sensitivity, and plasma glucose disposal were significantly impaired in participants with 1hPG ≥ 155 mg/dL (n = 11), who also showed nominally greater RaO (19%; P = 0.10). In multivariable models, postload RaO showed an independent effect on both 1hPG and glucose iAUC1h (partial r2 = 0.26 and 0.48, respectively; P < 0.003). The relative contribution of RaO to 1hPG (23%) and glucose iAUC1h (30%) was similar to that of early insulin secretion and peripheral insulin sensitivity and greater than that of hepatic insulin sensitivity.

CONCLUSIONS

Our data highlight the primary role of RaO as a major determinant of 1-hour postprandial glucose excursions in nondiabetic participants.

The STOP DIABETES study: when prevention works

Although many drugs are now available, a large effort is still needed to prevent diabetes. The STOP DIABETES study evaluated individuals at risk for type 2 diabetes (T2D) by a 2-h 75-g oral glucose tolerance test (OGTT). Based on the three main defective physiological responses, subjects were stratified as at low, intermediate, or high risk, and treated accordingly with lifestyle modifications and drugs. Participants at intermediate and high risk experienced the greatest reduction of T2D conversion. Interestingly, a group of individuals developing T2D presented a normal glucose tolerance at baseline, but a 1-h plasma glucose concentration > 155 mg/dL. These results are critical as prediabetes can increase the incidence of cardiovascular disease. Considering the timeframe between the first defects in glucose metabolism and the manifestation of diabetes complications, the effort to tackle the glycemic impairment as soon as possible represents an outstanding task to reduce the incidence of diabetes. Ideally, the earlier glycemic alterations are recognized, the lesser armamentarium needs to be used, and the lower is the expense in terms of drugs, complications, and related events and costs. Finally, a wealth of studies clearly demonstrated the importance of 1-h plasma glucose concentration, which has been proposed as an adjunctive diagnostic tool to detect prediabetes earlier. In conclusion, by an OGTT, a lot of individuals at risk for T2D may be detected when the central role for the 1-h plasma glucose concentration is also considered. Consequently, these subjects would be treated early and with less drugs and delay T2D complications.

1-Hour Post-OGTT Glucose Improves the Early Prediction of Type 2 Diabetes by Clinical and Metabolic Markers

CONTEXT

Early prediction of dysglycemia is crucial to prevent progression to type 2 diabetes. The 1-hour postload plasma glucose (PG) is reported to be a better predictor of dysglycemia than fasting plasma glucose (FPG), 2-hour PG, or glycated hemoglobin (HbA1c).

OBJECTIVE

To evaluate the predictive performance of clinical markers, metabolites, HbA1c, and PG and serum insulin (INS) levels during a 75-g oral glucose tolerance test (OGTT).

DESIGN AND SETTING

We measured PG and INS levels at 0, 30, 60, and 120 minutes during an OGTT in 543 participants in the Botnia Prospective Study, 146 of whom progressed to type 2 diabetes within a 10-year follow-up period. Using combinations of variables, we evaluated 1527 predictive models for progression to type 2 diabetes.

RESULTS

The 1-hour PG outperformed every individual marker except 30-minute PG or mannose, whose predictive performances were lower but not significantly worse. HbA1c was inferior to 1-hour PG according to DeLong test P value but not false discovery rate. Combining the metabolic markers with PG measurements and HbA1c significantly improved the predictive models, and mannose was found to be a robust metabolic marker.

CONCLUSIONS

The 1-hour PG, alone or in combination with metabolic markers, is a robust predictor for determining the future risk of type 2 diabetes, outperforms the 2-hour PG, and is cheaper to measure than metabolites. Metabolites add to the predictive value of PG and HbA1c measurements. Shortening the standard 75-g OGTT to 1 hour improves its predictive value and clinical usability.

Increased Rates of Meal Absorption Do Not Explain Elevated 1-Hour Glucose in Subjects With Normal Glucose Tolerance

Context

In subjects with normal fasting glucose (NFG) and normal glucose tolerance (NGT), glucose concentrations >155 mg/dL 1 hour after 75 g of oral glucose predict increased risk of progression to diabetes. Recently, it has been suggested that the mechanism underlying this abnormality is increased gut absorption of glucose.

Objective

We sought to determine the rate of systemic appearance of meal-derived glucose in subjects classified by their 1-hour glucose after a 75-g oral glucose challenge.

Design

This was a cross-sectional study. Participating subjects underwent a 75-g oral glucose challenge and a labeled mixed meal test.

Setting

An inpatient clinical research unit at an academic medical center.

Participants

Thirty-six subjects with NFG/NGT participated in this study.

Interventions

Subjects underwent an oral glucose tolerance test. Subsequently, they underwent a labeled mixed meal to measure fasting and postprandial glucose metabolism.

Main Outcome Measures

We examined β-cell function and the rate of meal appearance (Meal R_a) in NFG/NGT subjects. Subsequently, we examined the relationship of peak postchallenge glucose with Meal R_a and indices of β-cell function.

Results

Peak glucose concentrations correlated inversely with β-cell function. No relationship of Meal R_a with peak postchallenge glucose concentrations was observed.

Conclusion

In subjects with NFG/NGT, elevated 1-hour peak postchallenge glucose concentrations reflect impaired β-cell function rather than increased systemic meal appearance.

One-Hour Postload Hyperglycemia: Implications for Prediction and Prevention of Type 2 Diabetes

CONTEXT

Recently, a value of 1-hour postload glucose concentration (1-h-PG) ≥155 mg/dL (8.6 mmol/L) in individuals with normal glucose tolerance (NGT) has been found to be associated with an increased risk for future type 2 diabetes mellitus (T2DM). In this review, we analyze the implication of 1-h-PG determination in prediction of T2DM and cardiovascular disease.

DESIGN

A literature search was performed using MEDLINE. We included all English studies published up to February 2018 in peer-reviewed journals that examined the relationship between 1-h-PG and diabetes, cardiometabolic alterations, organ damage, and cardiovascular disease.

RESULTS

Several longitudinal studies have consistently shown that 1-h-PG ≥155 mg/dL can recognize individuals at increased risk for future T2DM among subjects with NGT. Additionally, we describe the pathophysiological abnormalities associated with 1-h-PG ≥155 mg/dL including impaired insulin sensitivity, β-cell dysfunction, and increased glucose intestinal absorption, which are known to be involved in T2DM pathogenesis. Importantly, numerous studies have demonstrated that a value of 1-h-PG ≥155 mg/dL in individuals with NGT is not only linked to an increased risk for future T2DM, but also able to identify those having a worse cardiovascular phenotype and an increased risk of adverse cardiovascular outcomes.

CONCLUSIONS

Although 1-h-PG determination is not currently recommended by the American Diabetes Association for identifying high-risk individuals, the available evidence indicates that a value of 1-h-PG ≥155 mg/dL may be a useful tool to recognize, among subjects with NGT, those at increased risk of T2DM and cardiovascular disease.

Lessons learned from the 1-hour post-load glucose level during OGTT: Current screening recommendations for dysglycaemia should be revised

This perspective covers a novel area of research describing the inadequacies of current approaches for diagnosing dysglycaemia and proposes that the 1-hour post-load glucose level during the 75-g oral glucose tolerance test may serve as a novel biomarker to detect dysglycaemia earlier than currently recommended screening criteria for glucose disorders. Considerable evidence suggests that a 1-hour post-load plasma glucose value ≥155 mg/dl (8.6 mmol/L) may identify individuals with reduced β-cell function prior to progressing to prediabetes and diabetes and is highly predictive of those likely to progress to diabetes more than the HbA_1c or 2-hour post-load glucose values. An elevated 1-hour post-load glucose level was a better predictor of type 2 diabetes than isolated 2-hour post-load levels in Indian, Japanese, and Israeli and Nordic populations. Furthermore, epidemiological studies have shown that a 1-hour PG ≥155 mg/dl (8.6 mmol/L) predicted progression to diabetes as well as increased risk for microvascular disease and mortality when the 2-hour level was <140 mg/dl (7.8 mmol/L). The risk of myocardial infarction or fatal ischemic heart disease was also greater among subjects with elevated 1-hour glucose levels as were risks of retinopathy and peripheral vascular complications in a Swedish cohort. The authors believe that the considerable evidence base supports redefining current screening and diagnostic recommendations with the 1-hour post-load level. Measurement of the 1-hour PG level would increase the likelihood of identifying a larger, high-risk group with the additional practical advantage of potentially replacing the conventional 2-hour oral glucose tolerance test making it more acceptable in a clinical setting.

The 1-h post-load plasma glucose as a novel biomarker for diagnosing dysglycemia

Identifying the earliest moment for intervention to avert progression to prediabetes and diabetes in high-risk individuals is a substantial challenge. As β-cell function is already compromised in prediabetes, attention should therefore be focused on identifying high-risk individuals earlier in the so-called pre-prediabetes stage. Biomarkers to monitor progression and identify the time point at which β-cell dysfunction occurs are therefore critically needed. Large-scale population studies have consistently shown that the 1-h plasma glucose (1-h PG) ≥ 155 mg/dl (8.6 mmol/l) during the oral glucose tolerance test detected incident type 2 diabetes and associated complications earlier than fasting plasma glucose or 2-h plasma glucose levels. An elevated 1-h PG level appears to be a better alternative to HbA1c [5.7-6.4% (37-47 mmol/mol)] or traditional glucose criteria for identifying high-risk individuals at a stage when ß-cell function is substantially more intact than in prediabetes. Diagnosing high-risk individuals earlier proffers the opportunity for potentially reducing progression to diabetes, development of microvascular complications and mortality, thereby advancing benefit beyond that which has been demonstrated in global diabetes prevention programs.

Oral hormonal therapy with ethinylestradiol–levonorgestrel improves insulin resistance, obesity, and glycogen synthase kinase-3 independent of circulating mineralocorticoid in estrogen-deficient rats

Estrogen deficiency has been associated with increased incidence of cardiovascular diseases , and recent clinical trials of standard formulations of hormonal therapies have not demonstrated consistent beneficial effects. Estrogen–progestin therapy has been used as exogenous estrogen to normalize depressed estrogen level during menopause. Ovariectomized rodents mimic an estrogen-deficient state in that they develop cardiometabolic dysfunction, including insulin resistance (IR). We therefore hypothesized that hormonal therapy with combined oral contraceptive steroids, ethinylestradiol–levonorgestrel (EEL), improves IR, obesity, and glycogen synthase kinase-3 (GSK-3) through reduction of circulating mineralocorticoid in ovariectomized rats. Twelve-week-old female Wistar rats were divided into 4 groups: sham-operated (SHM) and ovariectomized (OVX) rats were treated with or without EEL (1.0 μg ethinylestradiol and 5.0 μg levonorgestrel) daily for 8 weeks. Results showed that OVX or SHM + EEL treated rats had increased HOMA-IR (homeostatic model assessment of IR), 1 h postload glucose, HOMA-β, triglycerides (TG), total cholesterol (TC), TC/HDL cholesterol, TG/HDL cholesterol, plasma insulin, GSK-3, corticosterone, and aldosterone. On the other hand, OVX + EEL treatment ameliorated all these effects except that of aldosterone. Taken together, the results demonstrate that oral hormonal replacement with EEL improves IR and pancreatic β-cell function and suppresses GSK-3 and glucocorticoid independent of circulating aldosterone, suggesting a positive cardiometabolic effect of oral EEL therapy in estrogen-deficient rats.

No effect on the short-term of a decrease in blood viscosity on insulin resistance

BACKGROUND

Blood viscosity (BV) might influence glucose delivery to peripheral tissues and play an important role in insulin resistance and diabetes mellitus. However, the exact relationship between BV and insulin resistance is not yet clear.

OBJECTIVES

Aim of the present study is to evaluate the effects of the acute reduction in BV on insulin resistance, in healthy male subjects.

METHODS

Fifteen healthy male blood donors have been studied before and 48 hours after blood donation. Blood and plasma viscosity have been measured at 37°C with a cone-plate viscometer. Insulin resistance has been evaluated by euglycemic/hyperinsulinemic clamp in eight subjects, and by iHOMA2 Index in further seven subjects.

RESULTS

Blood viscosity was markedly reduced after blood donation (BV225 (cP) 4.53 ± 0.59 vs. 4.18 ± 0.31, p < 0.05). Insulin resistance was unchanged: MFFM clamp: 5.6 ± 4.5vs. 4.4 ± 2.2 and iHOMA2 Index 1.2 ± 0.6 vs. 1.2 ± 0.5, before vs. after respectively, p = NS. Blood pressure and lipids were unchanged after blood donation.

CONCLUSIONS

The present results demonstrate that acute reduction of BV in healthy male subjects does not change the insulin resistance, measured using both euglycemic/hyperinsulinemic clamp and iHOMA2 Index. Further intervention studies are needed to assess the effect that the reduction in BV can have in subjects with insulin resistance.

Abnormal 1-hour post-load glycemia during pregnancy impairs post-partum metabolic status: a single-center experience

PURPOSE

Recent evidence indicates that people with normal glucose tolerance (NGT) but 1-h post-load plasma glucose (1-h OGTT) ≥ 155 mg/dl have an increased risk for developing Type 2 diabetes mellitus (T2DM), determining a new risk category with deeper metabolic impairment. The aim of this study was to identify, among women with gestational diabetes (GDM), which alterations at OGTT during pregnancy are more frequently associated with 1-h OGTT ≥ 155 mg/dl at post-partum examination.

METHODS

Among 297 women affected by GDM, we retrospectively evaluated 244 resulted NGT after delivery. Based on post-partum glucose levels at 1-h OGTT, these people were divided into 188 cases (77.0%) with 1-h OGTT < 155 mg/dl (L-NGT) and 56 (23.0%) with 1-h OGTT ≥ 155 mg/dl (H-NGT).

RESULTS

Abnormal glucose levels at 1-h OGTT during pregnancy (≥ 180 mg/dl) were more frequent in H-NGT than in L-NGT (39.3 vs. 24.6%, odds ratio 3.7 [95% CI 1.4-9.6]; p = 0.016). Moreover, H-NGT showed more frequently the simultaneous alteration of all three OGTT plasma glucose values during pregnancy (10.7 vs. 2.1%, odds ratio 4.5 [95% CI 1.5-20.3]; p = 0.038) and less frequently the alteration of fasting plasma glucose alone (14.3 vs. 30.8%, odds ratio 0.4 [95% CI 0.1-0.7]; p = 0.028).

CONCLUSIONS

Abnormal 1-h OGTT during pregnancy predicts an increased risk for post-partum 1-h OGTT ≥ 155 mg/dl in women with previous GDM. Even if NGT after delivery, these women may require a closer long-term post-partum follow-up, being at higher risk to develop future glucose intolerance.

Enhanced Predictive Capability of a 1-Hour Oral Glucose Tolerance Test: A Prospective Population-Based Cohort Study

OBJECTIVE

To examine whether the 1-h blood glucose measurement would be a more suitable screening tool for assessing the risk of diabetes and its complications than the 2-h measurement.

RESEARCH DESIGN AND METHODS

We conducted a prospective population-based cohort study of 4,867 men, randomly selected from prespecified birth cohorts between 1921 and 1949, who underwent an oral glucose tolerance test with blood glucose measurements at 0, 1, and 2 h. Subjects were followed for up to 39 years, with registry-based recording of events. Discriminative abilities of elevated 1-h (≥8.6 mmol/L) versus 2-h (≥7.8 mmol/L) glucose for predicting incident type 2 diabetes, vascular complications, and mortality were compared using Kaplan-Meier analysis, Cox proportional hazards regression, and net reclassification improvement.

RESULTS

Median age was 48 years (interquartile range [IQR] 48-49). During follow-up (median 33 years [IQR 24-37]), 636 (13%) developed type 2 diabetes. Elevated 1-h glucose was associated with incident diabetes (hazard ratio 3.40 [95% CI 2.90-3.98], P < 0.001) and provided better risk assessment than impaired glucose tolerance (Harrell concordance index 0.637 vs. 0.511, P < 0.001). Addition of a 1-h measurement in subjects stratified by fasting glucose provided greater net reclassification improvement than the addition of a 2-h measurement (0.214 vs. 0.016, respectively). Finally, the 1-h glucose was significantly associated with vascular complications and mortality.

CONCLUSIONS

The 1-h blood glucose level is a stronger predictor of future type 2 diabetes than the 2-h level and is associated with diabetes complications and mortality.

Duodenal Sodium/Glucose Cotransporter 1 Expression Under Fasting Conditions Is Associated With Postload Hyperglycemia

CONTEXT

Type 2 diabetes (T2DM) is associated with a higher intestinal expression of the glucose transporters sodium/glucose cotransporter 1 (SGLT-1) and glucose transporter 2 (GLUT-2). It is currently unsettled whether prediabetes conditions characterized by postprandial hyperglycemia, such as impaired glucose tolerance (IGT) and normal glucose tolerance (NGT) with 1-hour postload glucose ≥155 mg/dL (8.6 mmol/L) (NGT-1h-high) are associated with increased expression of these glucose carriers in the intestine.

OBJECTIVE

We evaluated whether duodenal abundance of SGLT-1 and GLUT-2 is augmented in subjects with IGT and NGT-1h-high, in comparison with subjects with NGT and 1-hour postload glucose ˂155 mg/dL (NGT-1h-low).

DESIGN

Cross-sectional.

PATIENTS

A total of 54 individuals underwent an upper gastrointestinal endoscopy.

MAIN OUTCOME MEASURES

Duodenal SGLT-1 and GLUT-2 protein and messenger RNA levels were assessed by Western blot and reverse transcription polymerase chain reaction, respectively.

RESULTS

Of the 54 subjects examined, 18 had NGT-1h-low, 12 had NGT-1h-high, 12 had IGT, and 12 had T2DM. Duodenal SGLT-1 protein and messenger RNA levels were significantly higher in individuals with NGT-1h-high, IGT, or T2DM in comparison with NGT-1h-low subjects. GLUT-2 abundance was higher in individuals with T2DM in comparison with NGT-1h-low subjects; no substantial increase in GLUT-2 expression was observed in NGT-1h-high or IGT individuals. Univariate correlations showed that duodenal SGLT-1 abundance was positively correlated with 1-hour postload plasma glucose levels (r = 0.44; P = 0.003) but not with fasting or 2-hour postload glucose levels.

CONCLUSIONS

Duodenal SGLT-1 expression is increased in individuals with 1-hour postload hyperglycemia or IGT, as well as in subjects with T2DM, and it positively correlates with early postload glucose excursion.

[One-hour post-load plasma glucose: a better indicator of glucose metabolism for obstructive sleep apnea?]

OBJECTIVE

To assess the value of blood glucose at different time points in oral glucose tolerance test (OGTT), particularly one?hour post load plasma glucose (1 hPG), in evaluating glucose metabolism in adult patients with obstructive sleep apnea (OSA).

METHODS

Eighty nine adultswith newly diagnosed OSA were analyzed retrospectively for sleep architecture assessed using polysomnography and glucose metabolism assessed by OGTT at different time points (0, 30, 60, 120, and 180 min). Pearson's correlatives and multiple linear regression models were established to investigate the correlations between glucose metabolism and other indices including sleep architecture, apnea hypopnea index (AHI), mean and lowest oxygen saturation (MSO₂ and LSO₂) and obesity measurements.

RESULTS

The majority (67.4%) of the patients had abnormal 1 hPG, and 41.6% had abnormal 2 hPG. 1 hPG was positively correlated with neck circumference (r=0.245), abdomen circumference (r=0.231), systolic blood pressure (r=0.213), diastolic blood pressure (r=0.276) and AHI (r=0.324), and was negatively associated with MSO₂ (r=-0.341) and LSO₂ (r=-0.387) (all P<0.05). After controlling for age, BMI, neck and abdomen circumferences, 1 hPG was found to inversely correlated with MSO₂ (r=-0.253, P=0.032) and LSO₂ (r=-0.311, P=0.008). In non-obese OSA subgroup, 1 hPG was significantly associated with OSA-related indices, and regression models showed that LSO₂ and N2 were the two most important contributors to 1 hPG (adjusted R²=0.349, P<0.001); plasma glucose at other time points did not show such correlations.

CONCLUSIONS

1 hPG abnormality occurs earlier than 2 hPG in OSA patients. 1 hPG is significantly associated with OSA independent of obesity and may serve as a better index for measuring OSA-related glucose disorder.

[One-hour post-load plasma glucose: a better indicator of glucose metabolism for obstructive sleep apnea?]

OBJECTIVE

To assess the value of blood glucose at different time points in oral glucose tolerance test (OGTT), particularly one?hour post load plasma glucose (1 hPG), in evaluating glucose metabolism in adult patients with obstructive sleep apnea (OSA).

METHODS

Eighty nine adultswith newly diagnosed OSA were analyzed retrospectively for sleep architecture assessed using polysomnography and glucose metabolism assessed by OGTT at different time points (0, 30, 60, 120, and 180 min). Pearson's correlatives and multiple linear regression models were established to investigate the correlations between glucose metabolism and other indices including sleep architecture, apnea hypopnea index (AHI), mean and lowest oxygen saturation (MSO2 and LSO2) and obesity measurements.

RESULTS

The majority (67.4%) of the patients had abnormal 1 hPG, and 41.6% had abnormal 2 hPG. 1 hPG was positively correlated with neck circumference (r=0.245), abdomen circumference (r=0.231), systolic blood pressure (r=0.213), diastolic blood pressure (r=0.276) and AHI (r=0.324), and was negatively associated with MSO2 (r=-0.341) and LSO2 (r=-0.387) (all P<0.05). After controlling for age, BMI, neck and abdomen circumferences, 1 hPG was found to inversely correlated with MSO2 (r=-0.253, P=0.032) and LSO2 (r=-0.311, P=0.008). In non-obese OSA subgroup, 1 hPG was significantly associated with OSA-related indices, and regression models showed that LSO2 and N2 were the two most important contributors to 1 hPG (adjusted R2=0.349, P<0.001); plasma glucose at other time points did not show such correlations.

CONCLUSIONS

1 hPG abnormality occurs earlier than 2 hPG in OSA patients. 1 hPG is significantly associated with OSA independent of obesity and may serve as a better index for measuring OSA-related glucose disorder.

One-hour and two-hour postload plasma glucose concentrations are comparable predictors of type 2 diabetes mellitus in Southwestern Native Americans

AIMS/HYPOTHESIS

Elevated 2-h plasma glucose concentration (2 h-PG) during a 75 g OGTT predict the development of type 2 diabetes mellitus. However, 1-h plasma glucose concentration (1 h-PG) is associated with insulin secretion and may be a better predictor of type 2 diabetes. We aimed to investigate the association between 1 h-PG and 2 h-PG using gold standard methods for measuring insulin secretion and action. We also compared 1 h-PG and 2 h-PG as predictors of type 2 diabetes mellitus.

METHODS

This analysis included adult volunteers without diabetes, predominantly Native Americans of Southwestern heritage, who were involved in a longitudinal epidemiological study from 1965 to 2007, with a baseline OGTT that included measurement of 1 h-PG. Group 1 (n = 716) underwent an IVGTT and hyperinsulinaemic-euglycaemic clamp for measurement of acute insulin response (AIR) and insulin-stimulated glucose disposal (M), respectively. Some members of Group 1 (n = 490 of 716) and members of a second, larger, group (Group 2; n = 1946) were followed-up to assess the development of type 2 diabetes (median 9.0 and 12.8 years follow-up, respectively).

RESULTS

Compared with 2 h-PG (r = -0.281), 1 h-PG (r = -0.384) was more closely associated with AIR, whereas, compared with 1 h-PG (r = -0.340), 2 h-PG (r = -0.408) was more closely associated with M. Measures of 1 h-PG and 2 h-PG had similar abilities to predict type 2 diabetes, which did not change when both were included in the model. A 1 h-PG cut-off of 9.3 mmol/l provided similar levels of sensitivity and specificity as a 2 h-PG cut-off of 7.8 mmol/l; the latter is used to define impaired glucose tolerance, a recognised predictor of type 2 diabetes mellitus.

CONCLUSIONS/INTERPRETATION

The 1 h-PG was associated with important physiological predictors of type 2 diabetes and was as effective as 2 h-PG for predicting type 2 diabetes mellitus. The 1 h-PG is, therefore, an alternative method of identifying individuals with an elevated risk of type 2 diabetes mellitus.

Elevated 1-h post-challenge plasma glucose levels in subjects with normal glucose tolerance or impaired glucose tolerance are associated with whole blood viscosity

AIM

It has been suggested that glucose levels ≥155 mg/dl at 1-h during an oral glucose tolerance test (OGTT) may predict development of type 2 diabetes and cardiovascular events among adults with normal glucose tolerance (NGT 1 h-high). Studies showed a link between increased blood viscosity and type 2 diabetes. However, whether blood viscosity is associated with dysglycemic conditions such as NGT 1 h-high, impaired glucose tolerance (IGT) or impaired fasting glucose (IFG) is unsettled.

METHODS

1723 non-diabetic adults underwent biochemical evaluation and OGTT. A validated formula based on hematocrit and total plasma proteins was employed to estimate whole blood viscosity. Subjects were categorized into NGT with 1 h glucose <155 mg/dL (NGT-1 h-low), NGT-1 h-high, IFG and/or IGT.

RESULTS

Hematocrit and blood viscosity values appeared significantly higher in individuals with NGT 1 h-high, IFG and/or IGT as compared to NGT 1 h-low subjects. Blood viscosity was significantly correlated with age, waist circumference, blood pressure, HbA1c, fasting, 1- and 2-h post-challenge insulin levels, total cholesterol and low-density lipoprotein, triglycerides, fibrinogen, white blood cell, and inversely correlated with high-density lipoprotein and insulin sensitivity. Of the four glycemic parameters, 1-h post-challenge glucose showed the strongest correlation with blood viscosity (β = 0.158, P < 0.0001) in a multivariate regression analysis model including several atherosclerosis risk factors.

CONCLUSIONS

Our results demonstrate a positive relationship between blood viscosity and 1-h post-challenge plasma glucose. They also suggest that a subgroup of NGT individuals with 1-h post-challenge plasma >155 mg/dl have increased blood viscosity comparable to that observed in subjects with IFG and/or IGT.

One-hour post-load plasma glucose levels associated with decreased insulin sensitivity and secretion and early makers of cardiometabolic risk

PURPOSE

Obese adults with normal glucose tolerance (NGT) but with 1-hour post-load plasma glucose (1hPG) ≥ 155 mg/dl are at higher risk of developing type 2 diabetes (T2D) and cardiometabolic complications. Little information is available for the pediatric population, where recently, a lower cutoff, 132.5 mg/dl, has been suggested as being more sensitive to identify subjects at risk of T2D. Our aim was to assess whether obese Caucasian youth with 1hPG ≥ 132.5 mg/dl have worse insulin sensitivity and secretion and a worse cardiometabolic profile compared to obese youth with 1hPG < 132.5 mg/dl.

METHODS

Medical records of 244 (43% male; age: 11.1 ± 2.7years) overweight/obese children and adolescents, who had undergone an oral glucose tolerance test (OGTT), were retrieved. Anthropometric and biochemical data were collected from the hard copy archive. Indexes of insulin resistance (HOMA-IR), insulin sensitivity (WBISI), and insulin secretion (Insulinogenic Index, Disposition Index) were calculated.

RESULTS

Of the 244 records analyzed, 215 fulfilled criteria for NGT and had complete biochemical data. Among NGT patients, 42 (19.5%) showed 1hPG ≥ 132.5 mg/dL (high-NGT), while the remaining had 1hPG < 132.5 mg/dL (low-NGT). The high-NGT group showed a higher male prevalence (59.5 vs 37%), lower Disposition Index (0.54 [0.39-0.71] vs 0.79 [0.47-1.43]), and WBISI (0.24 [0.18-0.35] vs 0.33 [0.23-0.50]) than the low-NGT group. High-NGT subjects also showed a trend towards lower HDL-cholesterol and higher triglycerides/HDL-cholesterol ratio (2.13 [1.49-3.41] vs 1.66 [1.24-2.49]).

CONCLUSIONS

In overweight/obese NGT Caucasian youth a 1hPG ≥ 132.5 mg/dL was able to identify those with impaired insulin sensitivity and secretion and a trend towards a worse cardio-metabolic profile, a group likely at risk for future T2D.

An elevated 1-h post- load glucose level during the oral glucose tolerance test detects prediabetes

AIM

The objective of the study was to compare the diagnosis of dysglycemic states by conventional oral glucose tolerance test (OGTT) criteria (fasting and 2-h plasma glucose) with the 1-h post-load plasma glucose level.

MATERIAL AND METHODS

34 individuals (mean age: 55±13years; BMI: 27.7±6.3kg/m²) at risk for prediabetes were administered a 75g OGTT. Individuals with normal glucose tolerance (NGT) or prediabetes were identified according to fasting and/or 2-h plasma glucose (PG) concentrations. Subsequently, subjects were divided in 2 groups: group 1 (n=21) with a 1-h PG<155mg/dl and group 2 (n=13) with a 1-h PG≥155mg/dl. HOMA was performed to assess β-cell function and insulin sensitivity.

RESULTS

NGT or prediabetes based on conventional criteria correlated with the 1-h PG<or≥155mg/dl (p<0.001). Moreover, the 1-h PG≥155mg/dl was associated with higher HbA_1c levels (6.1±0.5 vs. 5.5±0.3%, p<0.001) and significantly impaired insulin secretion and hyperbolic product (BxS) on HOMA test vs. 1-h PG<155mg/dl.

CONCLUSION

The 1-h post-load plasma glucose value ≥155mg/dl is strongly associated with conventional criteria for (pre)diabetes and alterations of β-cell function.

One-hour postload plasma glucose concentration in people with normal glucose homeostasis predicts future diabetes mellitus: a 12-year community-based cohort study

OBJECTIVE

In Caucasians, plasma glucose concentration at 1 h during an oral glucose tolerance test (OGTT) may be a better predictor of future diabetes mellitus than the fasting or 2-h postload glucose concentration. We investigated whether the 1-h glucose concentration could be used to predict future diabetes mellitus in Asian ethnicity.

MEASUREMENTS

A total of 5703 Koreans with normal glucose tolerance were enrolled from the Korean Genome and Epidemiology Study. Indices of insulin sensitivity and β-cell function estimated from standard 75-g OGTTs performed every 2 years for 12 years were used to identify whether the 1-h glucose concentration could predict future diabetes mellitus.

RESULTS

The mean age and body mass index at baseline were 51·3 ± 8·7 years and 24·2 ± 3·0 kg/m² , respectively. During the 12-year follow-up, 593 subjects (10·3%) developed diabetes mellitus. The area under the receiver-operating characteristic curve for incident diabetes mellitus was higher for the 1-h postload glucose concentration than for the fasting or postload 2-h glucose concentration (0·74 vs 0·61 or 0·63). The cut-off value of ≥8·0 mmol/l identified incident diabetes mellitus with 70% sensitivity and 68% specificity. After adjusting for typical risk factors, subjects with a 1-h postload glucose concentration ≥8·0 mmol/l had lower β-cell function and a 2·84-fold increased risk of incident diabetes mellitus compared with their counterparts.

CONCLUSIONS

In this community-based 12-year prospective cohort study, 1-h postload plasma glucose concentration was an independent predictor of future diabetes mellitus and 8·0 mmol/l was suggested as a cut-off value.

Trajectories of Postload Plasma Glucose in the Development of Type 2 Diabetes in Japanese Adults

We aimed to clarify how the trajectories of 1-hour postload plasma glucose (PG) and 2-hour PG were different in the development of type 2 diabetes. Using data of repeated health checkups in Japanese workers from April 2006 to March 2016, longitudinal changes of fasting, 1-hour, and 2-hour PG on the oral glucose tolerance test were analyzed with a linear mixed effects model. Of the 1464 nondiabetic subjects at baseline, 112 subjects progressed to type 2 diabetes during the observation period (progressors). In progressors, 1-hour PG and 2-hour PG showed gradual increases with slopes of 1.33 ± 0.2 and 0.58 ± 0.2 mg/dL/year, respectively, followed by a steep increase by which they attained diabetes. Until immediately before the diabetes transition, age- and sex-adjusted mean level of 2-hour PG was 149 ± 2.7 mg/dL, 34 ± 2.7 (30%) higher compared to nonprogressors, while that of 1-hour PG was 206 ± 4.1 mg/dL, 60 ± 4.3 mg/dL (41%) higher compared to nonprogressors. In conclusion, diabetes transition was preceded by a mild elevation of 2-hour PG for several years or more. The elevation in 1-hour PG was larger than that of 2-hour PG until immediately before the transition to diabetes.

Delayed insulin secretion response during an OGTT is associated with an increased risk for incidence of diabetes in NGT subjects

AIMS

This study aimed to assess whether insulin secretion patterns during oral glucose tolerance tests (OGTTs) could predict future type 2 diabetes (T2D) in Chinese normal glucose tolerance (NGT) subjects.

METHODS

A total of 558 NGT, 419 newly diagnosed impaired glucose tolerance, and 694 newly diagnosed T2D patients were assessed. NGT subjects were grouped based on the time of peak insulin secretion during a 3h- OGTT; at 30min (InsP30), 60min (InsP60), 120min (InsP120), or 180min (InsP180), respectively. NGT subjects were followed up for an average duration of 5.58±1.08years. Beta-cell function was estimated by Stumvoll insulin secretion.

RESULTS

The InsP120 and InsP180 groups had lower Stumvoll first-phase insulin secretion levels compared with InsP30. At 5.58±1.08years, 25 (5.39%) NGT subjects had developed T2D. The cumulative incidence rate of diabetes was higher in the InsP120 and InsP180 groups (8.94%), compared with InsP30 (1.48%) (P<0.05). The adjusted relative risk for incident diabetes was 7.30 (95% CI: 1.53-34.72) times higher in the InsP120 and InsP180 groups.

CONCLUSIONS

NGT subjects with late insulin responses had defective early insulin secretion and were at higher risk of developing diabetes. Insulin secretion patterns could be a useful T2D predictor in the Chinese population.

A Prospective Study of Renal Transplant Recipients: A Fall in Insulin Secretion Underpins Dysglycemia After Renal Transplantation

Background

Dysglycemia (encompassing impaired glucose tolerance and diabetes mellitus) arising after renal transplantation is common and confers a significant cardiovascular mortality risk. Nonetheless, the pathophysiology of posttransplant dysglycemia is not well described. The aim of this study was to prospectively and comprehensively assess glucose handling in renal transplant recipients from before to 12 months after transplantation to determine the underpinning pathophysiology.

Materials and Methods

Intravenous and oral glucose tolerance testing was conducted before and at 3 and 12 months posttransplantation. An intravenous glucose tolerance test was also performed on day 7 posttransplantation. We followed up 16 transplant recipients for 3 months and 14 recipients for 12 months. Insulin secretion, resistance and a disposition index (DI (IV)), a measure of β cell responsiveness in the context of prevailing insulin resistance, were also determined.

Results

At 12 months, 50% of renal transplant recipients had dysglycemia. Dysglycemia was associated with a dramatic fall in DI (IV) and this loss in β cell function was evident as early as 3 months posttransplantation (23.5 pretransplant; 6.4 at 3 months and 12.2 at 12 months posttransplant). Differences in the β cell response to oral glucose challenge were evident pretransplant in those destined to develop dysglycemia posttransplant (2-hour blood glucose level 5.6 mmol/L versus 6.8 mmol/L; P < 0.01).

Conclusions

Dysglycemia after renal transplantation is common, and the loss of insulin secretion is a major contributor. Subclinical differences in glucose handling are evident pretransplant in those destined to develop dysglycemia potentially heralding a susceptible β cell which under the stressors associated with transplantation fails.

One-hour plasma glucose as a predictor of the development of Type 2 diabetes in Japanese adults

AIMS

To test the hypothesis that 1-h plasma glucose in an oral glucose tolerance test is a better predictor of the development of diabetes than 2-h plasma glucose, independently of indices of insulin secretion or action in Japanese adults.

METHODS

A historical cohort study was conducted in 1445 Japanese workers who did not have diabetes. The association between 1-h plasma glucose and the development of Type 2 diabetes was analysed.

RESULTS

Overall, 95 of the study participants developed Type 2 diabetes during a mean follow-up of 4.5 years. The area under the receiver-operating characteristic curve for 1-h plasma glucose for future diabetes [0.88 (95% CI 0.84-0.91)] was greater than that for 2-h plasma glucose [0.79 (95% CI 0.74-0.84)], and for insulinogenic [0.73 (95% CI 0.68-0.78)] and disposition indices [0.79 (95% CI 0.74-0.84); P < 0.05]. Compared with the first quartile, the hazard ratio for future diabetes in the fourth quartile of 1-h plasma glucose was 42.5 [95% CI 5.7-315.2 (P < 0.05)] and the hazard ratio in the fourth quartile of 2-h plasma glucose was 4.4 [95% CI 1.8-10.8 (P < 0.05)], after adjustments for covariates including fasting plasma glucose. The significance of the elevated hazard ratio in the fourth quartile of 1-h plasma glucose was maintained after adjustments for 2-h plasma glucose, insulinogenic index or disposition index, whereas the elevation of the hazard ratio in the fourth quartile of 2-h plasma glucose was diminished and was no longer significant after adjustments for 1-h plasma glucose.

CONCLUSIONS

One-hour plasma glucose had a greater association with the future development of Type 2 diabetes than did 2-h plasma glucose, independently of oral glucose tolerance test-derived indices of insulin action in a Japanese population.

Effects of exercise training alone vs a combined exercise and nutritional lifestyle intervention on glucose homeostasis in prediabetic individuals: a randomised controlled trial

AIMS/HYPOTHESIS

Although the Diabetes Prevention Program (DPP) established lifestyle changes (diet, exercise and weight loss) as the 'gold standard' preventive therapy for diabetes, the relative contribution of exercise alone to the overall utility of the combined diet and exercise effect of DPP is unknown; furthermore, the optimal intensity of exercise for preventing progression to diabetes remains very controversial. To establish clinical efficacy, we undertook a study (2009 to 2013) to determine: how much of the effect on measures of glucose homeostasis of a 6 month programme modelled after the first 6 months of the DPP is due to exercise alone; whether moderate- or vigorous-intensity exercise is better for improving glucose homeostasis; and to what extent amount of exercise is a contributor to improving glucose control. The primary outcome was improvement in fasting plasma glucose, with improvement in plasma glucose AUC response to an OGTT as the major secondary outcome.

METHODS

The trial was a parallel clinical trial. Sedentary, non-smokers who were 45-75 year old adults (n = 237) with elevated fasting glucose (5.28-6.94 mmol/l) but without cardiovascular disease, uncontrolled hypertension, or diabetes, from the Durham area, were studied at Duke University. They were randomised into one of four 6 month interventions: (1) low amount (42 kJ kg body weight(-1) week(-1) [KKW])/moderate intensity: equivalent of expending 42 KKW (e.g. walking ∼16 km [8.6 miles] per week) with moderate-intensity (50% [Formula: see text]) exercise; (2) high amount (67 KKW)/moderate intensity: equivalent of expending 67 KKW (∼22.3 km [13.8 miles] per week) with moderate-intensity exercise; (3) high amount (67 KKW)/vigorous intensity: equivalent to group 2, but with vigorous-intensity exercise (75% [Formula: see text]); and (4) diet + 42 KKW moderate intensity: same as group 1 but with diet and weight loss (7%) to mimic the first 6 months of the DPP. Computer-generated randomisation lists were provided by our statistician (G. P. Samsa). The randomisation list was maintained by L. H. Willis and C. A. Slentz with no knowledge of or input into the scheduling, whereas all scheduling was done by L. A. Bateman, with no knowledge of the randomisation list. Subjects were automatically assigned to the next group listed on the randomisation sheet (with no ability to manipulate the list order) on the day that they came in for the OGTT, by L. H. Willis. All plasma analysis was done blinded by the individuals doing the measurements (i.e. lipids, glucose, insulin). Subjects and research staff (other than individuals analysing the blood) were not blinded to the group assignments.

RESULTS

Number randomised, completers and number analysed with complete OGTT data for each group were: low-amount/moderate-intensity (61, 43, 35); high-amount/moderate-intensity (61, 44, 40); high-amount/vigorous-intensity (61, 43, 38); diet/exercise (54, 45, 37), respectively. Only the diet and exercise group experienced a decrease in fasting glucose (p < 0.001). The means and 95% CIs for changes in fasting glucose (mmol/l) for each group were: high-amount/moderate-intensity -0.07 (-0.20, 0.06); high-amount/vigorous 0.06 (-0.07, 0.19); low-amount/moderate 0.05 (-0.05, 0.15); and diet/exercise -0.32 (-0.46, -0.18). The effects sizes for each group (in the same order) were: 0.17, 0.15, 0.18 and 0.71, respecively. For glucose tolerance (glucose AUC of OGTT), similar improvements were observed for the diet and exercise (8.2% improvement, effect size 0.73) and the 67 KKW moderate-intensity exercise (6.4% improvement, effect size 0.60) groups; moderate-intensity exercise was significantly more effective than the same amount of vigorous-intensity exercise (p < 0.0207). The equivalent amount of vigorous-intensity exercise alone did not significantly improve glucose tolerance (1.2% improvement, effect size 0.21). Changes in insulin AUC, fasting plasma glucose and insulin did not differ among the exercise groups and were numerically inferior to the diet and exercise group.

CONCLUSIONS/INTERPRETATION

In the present clinical efficacy trial we found that a high amount of moderate-intensity exercise alone was very effective at improving oral glucose tolerance despite a relatively modest 2 kg change in body fat mass. These data, combined with numerous published observations of the strong independent relation between postprandial glucose concentrations and prediction of future diabetes, suggest that walking ∼18.2 km (22.3 km prescribed with 81.6% adherence in the 67 KKW moderate-intensity group) per week may be nearly as effective as a more intensive multicomponent approach involving diet, exercise and weight loss for preventing the progression to diabetes in prediabetic individuals. These findings have important implications for the choice of clinical intervention to prevent progression to type 2 diabetes for those at high risk.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00962962 FUNDING: The study was funded by National Institutes for Health National Institute of Diabetes and Digestive and Kidney Diseases (NIH-NDDK) (R01DK081559).

The 1-hour post-load glucose level is more effective than HbA1c for screening dysglycemia

AIM

To assess the performance of HbA1c and the 1-h plasma glucose (PG ≥ 155 mg/dl; 8.6 mmol/l) in identifying dysglycemia based on the oral glucose tolerance test (OGTT) from a real-world clinical care setting.

METHODS

This was a diagnostic test accuracy study. For this analysis, we tested the HbA1c diagnostic criteria advocated by the American Diabetes Association (ADA 5.7-6.4 %) and International Expert Committee (IEC 6.0-6.4 %) against conventional OGTT criteria. We also tested the utility of 1-h PG ≥ mg/dl; 8.6 mmol/l. Prediabetes was defined according to ADA-OGTT guidelines. Spearman correlation tests were used to determine the relationships between HbA1c, 1-h PG with fasting, 2-h PG and indices of insulin sensitivity and β-cell function. The levels of agreement between diagnostic methods were ascertained using Cohen's kappa coefficient (Κ). Receiver operating characteristic (ROC) curve was used to analyze the performance of the HbA1c and 1-h PG test in identifying prediabetes considering OGTT as reference diagnostic criteria. The diagnostic properties of different HbA1c thresholds were contrasted by determining sensitivity, specificity and likelihood ratios (LR).

RESULTS

Of the 212 high-risk individuals, 70 (33 %) were identified with prediabetes, and 1-h PG showed a stronger association with 2-h PG, insulin sensitivity index, and β-cell function than HbA1c (P < 0.05). Furthermore, the level of agreement between 1-h PG ≥ 155 mg/dl (8.6 mmol/l) and the OGTT (Κ[95 % CI]: 0.40[0.28-0.53]) diagnostic test was stronger than that of ADA-HbA1c criteria 0.1[0.03-0.16] and IEC criteria (0.17[0.04-0.30]). The ROC (AUC[95 % CI]) for HbA1c and 1-h PG were 0.65[0.57-0.73] and 0.79[0.72-0.85], respectively. Importantly, 1-h PG ≥ 155 mg/dl (8.6 mmol/l) showed good sensitivity (74.3 % [62.4-84.0]) and specificity 69.7 % [61.5-77.1]) with a LR of 2.45. The ability of 1-h PG to discriminate prediabetes was better than that of HbA1c (∆AUC: -0.14; Z value: 2.5683; P = 0.01022).

CONCLUSION

In a real-world clinical practice setting, the 1-h PG ≥ 155 mg/dl (8.6 mmol/l) is superior for detecting high-risk individuals compared with HbA1c. Furthermore, HbA1c is a less precise correlate of insulin sensitivity and β-cell function than the 1-h PG and correlates poorly with the 2-h PG during the OGTT.

β-Cell Function and Insulin Sensitivity in Normal Glucose-Tolerant Subjects Stratified by 1-Hour Plasma Glucose Values

AIM

This study was designed to assess β-cell function and insulin sensitivity indices among normal glucose tolerance (NGT) subjects stratified by 1-h plasma glucose (1hPG) values during an oral glucose tolerance test (OGTT).

MATERIALS AND METHODS

One hundred sixty-six NGT subjects underwent a five-point OGTT, and glucose and insulin levels were estimated. We calculated the following indices: (a) β-cell function (homeostasis assessment model-β-cell function [HOMA-β] and Insulinogenic Index [IGI]) and (b) insulin sensitivity (homeostasis assessment model-insulin resistance [HOMA-IR], Matsuda Index, and Insulin Sensitivity Index [ISI]).

RESULTS

NGT subgroups with elevated 1hPG values (i.e., 1hPG ≥143 to <155 mg/dL and 1hPG ≥155 mg/dL) did not differ from those with 1hPG <143 mg/dL by HOMA-β (P = 0.236) but had significantly lower IGIs (367 ± 239 vs. 257 ± 243 vs. 246 ± 239; P = 0.019). With respect to ISIs, HOMA-IR was not significantly different among the groups (P = 0.103). However, the Matsuda Index (11.2 ± 5.0 vs. 7.4 ± 4.8 vs. 5.5 ± 4.9; P < 0.001) and ISI (0.015 ± 0.010 vs. 0.012 ± 0.006 vs. 0.011 ± 0.011; P = 0.028) were significantly lower in subjects with elevated 1hPG values.

CONCLUSIONS

NGT subjects with elevated 1hPG levels have alterations in β-cell function and insulin sensitivity compared with those with normal 1hPG levels.

One-Hour Postload Hyperglycemia Is a Stronger Predictor of Type 2 Diabetes Than Impaired Fasting Glucose

CONTEXT

Subjects with normal glucose tolerance (NGT) but 1-h postload glucose ≥ 155 mg/dL (NGT-1h-high) exhibit an intermediate cardiometabolic risk profile between individuals with NGT and impaired glucose tolerance (IGT).

OBJECTIVE

This study aimed to evaluate whether NGT-1h-high subjects have different cardiometabolic characteristics and an increased risk of type 2 diabetes compared with individuals with isolated impaired fasting glucose (IFG).

SETTING, DESIGN, AND PATIENTS

A cross-sectional analysis was performed on 595 nondiabetic subjects who underwent an oral glucose tolerance test and an euglycemic hyperinsulinemic clamp in an ambulatory care setting. In addition, a longitudinal analysis was performed on 392 individuals, who were reexamined after a followup of 5.2 ± 0.9 y.

MAIN OUTCOME MEASURES

Insulin sensitivity, beta-cell function, and risk of developing diabetes were measured.

RESULTS

Subjects with NGT-1h-high have a significant reduction of peripheral insulin sensitivity and beta-cell function, assessed by the disposition index, compared with either 1-h postload glucose < 155 mg/dL (NGT-1h-low) or IFG individuals, but not compared with IGT. Among the 392 subjects studied in the longitudinal analysis the incidence rate of type 2 diabetes over the follow-up period was 2.9, 16.7, 12.5, and 31.4% for subjects with NGT-1h-low, NGT-1h-high, IFG, and IGT, respectively. In a Cox proportional hazard regression analysis the risk of developing diabetes for NGT-1h-high subjects was 4.02 (95% confidence interval [CI] 1.06-15.26); an even higher risk (6.67; 95% CI, 2.09-21.24) was observed in subjects with IGT, but not in the isolated IFG group (1.91; 95% CI, 0.44-8.29).

CONCLUSIONS

NGT-1h-high subjects exhibit a higher risk of developing diabetes than those with IFG or NGT-1h-low, likely due to decreased insulin sensitivity and beta-cell function.