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Context: In subjects with normal glucose tolerance (NGT) 1-hour postload plasma glucose (1-h oral glucose tolerance test [OGTT]) of >155 mg/dL predicts type 2 diabetes (T2DM) and is associated with subclinical atherosclerosis., Objective: The purpose of this study was to evaluate β-cell function, insulin resistance, and cardiovascular risk profile in subjects with NGT with a 1-h OGTT glucose of >155 mg/dL., Patients and Methods: The GENFIEV (Genetics, PHYsiopathology, and Evolution of Type 2 diabetes) study is a multicenter study recruiting individuals at high risk of T2DM. A total of 926 subjects underwent a 75-g OGTT for assessment of plasma glucose and C-peptide for mathematical modeling of β-cell function (derivative and proportional control). Fasting insulin, lipid profile, and clinical parameters were determined as well., Results: A 1-hour OGTT glucose of >155 mg/dL was found in 39% of subjects with NGT, 76% with impaired fasting glucose (IFG), 90% with impaired glucose tolerance (IGT), and 99% and 98% with IFG + IGT or newly diagnosed T2DM, respectively. Among subjects with NGT (n = 474), those with 1-hour OGTT glucose of >155 mg/dL were more insulin-resistant and had worse β-cell function than those with 1-hour OGTT glucose of ≤155 mg/dL. Moreover, glycosylated hemoglobin, blood pressure, low-density lipoprotein cholesterol, and triglycerides were higher in subjects with NGT with 1-hour OGTT glucose of >155 mg/dL, whereas high-density lipoprotein cholesterol was lower compared with that in subjects with NGT with 1-hour OGTT glucose of ≤155 mg/dL. Compared with subjects with IGT, those with NGT with 1-hour OGTT glucose of >155 mg/dL had comparable cardiovascular risk profile and insulin resistance but slightly better β-cell function., Conclusions: Among subjects with NGT, those with 1-hour OGTT glucose of >155 mg/dL showed lower insulin sensitivity, impaired β-cell function, and worse cardiovascular risk profile and therefore are at greater risk of developing T2DM and cardiovascular disease.

OBJECTIVE-To ascertain to which extent the use of HbA1c and oral glucose tolerance test (OGTT) for diagnosis of glucose tolerance could identify individuals with different pathogenetic mechanisms and cardiovascular risk profile. RESEARCH DESIGN AND METHOD-A total of 844 subjects (44%men; age 49.5±11 years; BMI 29±5 kg/m2) participated in this study. Parameters of β-cell function were derived from deconvolution of the plasma C-peptide concentration after a 75-g OGTT and insulin sensitivity assessed by homeostasismodel assessment of insulin resistance (IR). Cardiovascular risk profile was based on determination of plasma lipids and measurements of body weight, waist circumference, and blood pressure. Glucose regulation categories by OGTT and HbA1c were compared with respect to insulin action, insulin secretion, and cardiovascular risk profile. RESULT-OGTT results showed 42% of the subjects had prediabetes and 15% had type 2 diabetes mellitus (T2DM), whereas the corresponding figures based on HbA1c were 38 and 11%, with a respective concordance rate of 54 and 44%. Subjects meeting both diagnostic criteria for prediabetes presented greater IR and impairment of insulin secretion and had aworse cardiovascular risk profile than those with normal glucose tolerance at both diagnostic methods. In a logistic regression analyses adjusted for age, sex, and BMI, prediabetic subjects, and even more T2DM subjects by OGTT, had greater chance to have IR and impaired insulin secretion. CONCLUSION-HbA1c identifies a smaller proportion of prediabetic individuals and even a smaller proportion of T2DM individuals than OGTT, with no difference in IR, insulin secretion, and cardiovascular risk profile. Subjects fulfilling both diagnostic methods for prediabetes or T2DM are characterized by a worse metabolic profile. [ABSTRACT FROM AUTHOR]