Association of traits of metabolic syndrome with glucose abnormalities

The association of glucose abnormalities (GAs) with the early appearance of traits of the metabolic syndrome (MS) was studied in an unselected sample of apparently healthy Urban Hispanics. GAs were defined as impaired fasting glucose (IFG), impaired glucose tolerance (IGT), and newly diagnosed diabetes mellitus (DM). Overall, GAs were associated with older age, abdominal obesity, low high-density lipoprotein cholesterol levels, hypertriglyceridemia, hyperinsulinemia, hypertension, and MS. Prevalence of MS defined as per NCPE-ATPIII was the greatest in subjects with DM (54.3%) and with combined abnormalities (IFG + IGT) (54.1%; P > 0.5). Similar prevalence of MS was found in subjects with isolated IFG (34.3%) and isolated IGT (36.8%) but higher than in normal fasting-glucose tolerant individuals (23.3%) (P < 0.01). The average number of traits of the MS coexisting in normal fasting glucose-tolerant individuals was 1.6 [95% confidence interval (CI), 1.5-1.8; median 2], in isolated IFG: 2.05 (95% CI, 1.8-2.2; median 2); isolated IGT: 2.16 (95% CI, 1.8-2.3; median 2); combined IFG + IGT: 2.7 (95% CI, 2.3-3.1; median 3); and DM: 2.7 (95% CI, 2.25-3.1; median 3) (P < 0.01). Postload insulin levels were higher in isolated IGT than in isolated IFG, whereas HOMA-IR was higher in IFG. Indices of early and total insulin secretion were markedly reduced in DM, IFG-IGT, and IGT. In conclusion, GAs are strongly associated with the number and severity of traits of the MS, defects in insulin secretion, and sustained hyperinsulinemia in response to oral glucose. Subjects with combined GA and newly diagnosed type 2 DM had not only an increased prevalence of MS, but also the MS was characterized by the presence of more than 3 traits, and by a greater severity of each of the coexisting traits.