Abnormal Glucose Tolerance and Increased Risk for Cardiovascular Disease in Japanese-Americans With Normal Fasting Glucose

Abstract

OBJECTIVE— To compare the American Diabetes Association (ADA)fasting glucose and the World Health Organization (WHO) oral glucose tolerance test (OGTT) criteria for diagnosing diabetes and detecting people at increased risk for cardiovascular disease (CVD). RESEARCH DESIGN AND METHODS— Study subjects were 596 Japanese-Americans. Fasting insulin, lipids, and C-peptide levels; systolic and diastolic blood pressures (BPs); BMI (kg/m2); and total and intra-abdominal body fat distribution by computed tomography (CT) were measured. Study subjects were categorized by ADA criteria as having normal fasting glucose (NFG), impaired fasting glucose (IFG), and diabetic fasting glucose and by WHO criteria for a 75-g OGTT as having normal glucose tolerance(NGT), impaired glucose tolerance (IGT), and diabetic glucose tolerance(DGT). RESULTS— Of 503 patients with NFG, 176 had IGT and 20 had DGT. These patients had worse CVD risk factors than those with NGT. The mean values for NGT, IGT, and DGT, respectively, and analysis of covariance Pvalues, adjusted for age and sex, are as follows: intra-abdominal fat area by CT 69.7, 95.0, and 101.1 cm2 (P < 0.0001); total CT fat area 437.7, 523.3, and 489.8 cm2 (P < 0.0001); fasting triglycerides 1.40, 1.77, and 1.74 mmol/l (P = 0.002); fasting HDL cholesterol 1.56, 1.50, and 1.49 mmol/l (P = 0.02); C-peptide 0.80,0.90, 0.95 nmol/l (P = 0.002); systolic BP 124.9, 132.4, and 136.9 mmHg (P = 0.0035); diastolic BP 74.8, 77.7, and 78.2 mmHg (P= 0.01). CONCLUSIONS— NFG patients who had IGT or DGT had more intra-abdominal fat and total adiposity; higher insulin, C-peptide, and triglyceride levels; lower HDL cholesterol levels; and higher BPs than those with NGT. Classification by fasting glucose misses many Japanese-Americans with abnormal glucose tolerance and less favorable cardiovascular risk profiles.