Glucose Abnormalities in Hispanics: How Long Before Type 2 Diabetes Mellitus?

Objectives. To determine the screening value of fasting plasma glucose and insulin in detecting glucose intolerance and diabetes mellitus (DM) in “healthy” Hispanics. Background. Glucose abnormalities precede development of diabetes mellitus. However, only fasting glucose levels are used in clinical practice, and its diagnostic value varies among ethnicities. Methods. Oral glucose tolerance testing was conducted in 592 Hispanics. A cross-sectional design was employed. Results. GA were found in 34% of subjects, defined as impaired fasting glucose (IFG) (13.3%), IGT (6.9%), combined IFG+IGT (7.8%) and type2-DM (6.5%). FPG of 5.6-6.9mmol/l diagnostic of IFG missed 47.1% of subjects with IGT, and FPG > 7.0mmol/l missed 53.9% of DM. IFG showed a sensitivity of 52.9 % and a specificity of 83% in predicting IGT. The diagnostic yield, expressed by the positive predictive value was poor (36.8%). GA were associated with abdominal obesity, hypertriglyceridemia, hyperinsulinemia, hypertension and metabolic syndrome (MS). Prevalence of MS was greater in DM=IFG+IGT > IGT=IFG > controls. Post-load hyperinsulinemia and hyperglycemia was higher in IGT than in IFG; whereas HOMA-IR was higher in IFG. Insulin secretion was reduced in DM, IFG-IGT and IGT. Conclusion. Diagnosis of GA must include both, fasting and 2-hour post-load glucose levels. Presence of fasting and post-load hyperglycemia-hyperinsulinemia in one individual may explain the increased risk in combined IFG-IGT and in DM. Because of its 19 high prevalence, silent course, and associated increased risk, full-scale screening programs and aggressive management of GA must be implemented.