Physical Activity and Improvement of Glycemia in Prediabetes by Different Diagnostic Criteria.

Context: The effects of physical activity (PA) on improvement of glycemia may differ between prediabetic individuals defined by oral glucose tolerance test vs glycated hemoglobin (HbA1c). Objective: We studied the association between PA and improvement of glycemia in individuals with prediabetes defined by glucose vs HbA1c criteria. Design, Setting, and Participants: From the Whitehall II study, 957 participants with prediabetes defined by isolated impaired fasting glucose (i-IFG), isolated impaired glucose tolerance (i-IGT), or both and 457 with prediabetes defined by HbA1c were included. Main Outcome Measures: The associations of PA with concomitant changes in glucose-related outcomes during 5 years of follow-up were analyzed. A recursive partitioning analysis was performed to study heterogeneity in the association between baseline PA and the probability of reversion to normoglycemia. Results: After 5 years of follow-up, 405 (42%) individuals with glucose-defined prediabetes reverted to normal glucose tolerance (NGT). A 5-year increase in moderate-to-vigorous-intensity PA was associated with improvements in insulin sensitivity and ß-cell function, but PA was not generally associated with reversion to NGT. Only among women ≥50 years with i-IFG or i-IGT, higher amounts of PA were associated with higher probability of reversion to NGT. In HbA1c-defined prediabetes, only 20 individuals (4.4%) reverted to normoglycemia, and PA was not associated with improvement in glycemic markers. Conclusions: PA may be particularly important for reversion to normoglycemia among older women with i-IFG or i-IGT. Individuals with prediabetes identified by HbA1c have a low probability of reversion to normoglycemia, and their changes in glycemia are not related to PA.

The changing diagnosis of gestational diabetes mellitus: does anyone miss out?

Our aim was to identify women diagnosed with gestational diabetes mellitus (GDM) using 1999 WHO diagnostic criteria but who would be now classified as normal glucose tolerance (NGT) using updated criteria. We demonstrate that this category change affected 3.3% women and they have a limited increased risk of adverse outcomes.

Shape of glucose, insulin, C-peptide curves during a 3-h oral glucose tolerance test: any relationship with the degree of glucose tolerance?

We aimed to analyze the shape of the glucose, insulin, and C-peptide curves during a 3-h oral glucose tolerance test (OGTT). Another aim was defining an index of shape taking into account the whole OGTT pattern. Five-hundred ninety-two OGTT curves were analyzed, mainly from women with former gestational diabetes, with glycemic concentrations characterized by normal glucose tolerance (n = 411), impaired glucose metabolism (n = 134), and Type 2 diabetes (n = 47). Glucose curves were classified according to their shape (monophasic, biphasic, triphasic, and 4/5-phases), and the metabolic condition of the subjects, divided according to the glucose shape stratification, was analyzed. Indices of shape based on the discrete second-order derivative of the curve patterns were also defined. We found that the majority of the glucose curves were monophasic (n = 262). Complex shapes were less frequent but not rare (n = 37 for the 4/5-phases shape, i.e., three peaks). There was a tendency toward the amelioration of the metabolic condition for increasing complexity of the shape, as indicated by lower glucose concentrations, improved insulin sensitivity and ß-cell function. The shape index computed on C-peptide, WHOSH(CP) (WHole-Ogtt-SHape-index-C-peptide), showed a progressive increase [monophasic: 0.93 ± 0.04 (dimensionless); 4/5-phases: 1.35 ± 0.14], and it showed properties typical of ß-cell function indices. We also found that the type of glucose shape is often associated to similar insulin and C-peptide shape. In conclusion, OGTT curves can be characterized by high variability, and complex OGTT shape is associated with better glucose tolerance. WHOSH(CP) (WHole-Ogtt-SHape-index) may be a powerful index of ß-cell function much simpler than model-based indices.

Comparability of indices for insulin resistance and insulin secretion determined during oral glucose tolerance tests.

BACKGROUND: Impaired insulin secretion (IS) and insulin resistance (IR) play an essential role in the pathogenesis of type 2 diabetes mellitus. Several simplifying indices were developed that calculate IS and/or IR from venous insulin and glucose concentrations. The aim of the present study was to compare these indices with each other and with regard to their efficiency to differentiate between non-diseased and diabetic glucose tolerance states. METHODS: Oral glucose tolerance tests were performed in 301 subjects. The study group was divided into five groups according to WHO/American Diabetes Association (ADA) cut-off values: apparently normotolerant, diabetic, isolated 2-h post-challenge hyperglycemic, isolated fasting hyperglycemic and intermediate groups. The minimal error rate (diagnostic non-efficiency) indicating a misclassification of a diabetic tolerance state was determined for 12 indices. RESULTS: The error rate was lower than 15% for the index of Cederholm and Wibell and for the indices of Stumvoll et al. The misclassification rates for the other indices (index of Matsuda and de Fronzo, index of Myllynen et al., HOMA IR, HOMA beta-cell, FIRI, QUICKI, index of McAuley and insulinogenic index) were 20-27%; however, the diagnostic sensitivity was close to a 1:1 chance of a correct decision. The hypothesis that isolated post-prandial hyperglycemia (IPH) and isolated fasting hyperglycemia (IFH) differ in their insulin sensitivity and insulin response could not be supported by the present results. CONCLUSIONS: The indices of Cederholm and Wibell and of Stumvoll et al. were found to be appropriate as diagnostic indicators of the pathogenesis of diabetic glucose tolerance and were more closely related to the glucose tolerance state than the other indices.