Metabolic and adipose risk factors for NIDDM and coronary disease in third- generation Japanese-American men and women with impaired glucose tolerance

Summary  Since second-generation (Nisei) Japanese Americans are prone to develop the insulin resistance syndrome, younger third-generation (Sansei) Japanese Americans from a cross-sectional 10% volunteer sample of Sansei men (n = 115) and women (n = 115) 34 years or older in King County, Washington with normal glucose tolerance or IGT were examined for metabolic and adipose risk factors associated with this syndrome. After an overnight 10-h fast, blood samples were taken for measurement of glucose, insulin, C-pep-tide, lipids, and lipoproteins, followed by a 3-h 75-g oral glucose tolerance test with blood samples taken for glucose, insulin, and C-peptide measurement. BMI (kg/m2), skinfolds, and body fat areas (by computed tomography) were measured. IGT was diagnosed in 19 % of the men and 31 % of the women. Men with IGT had more adiposity, both overall and in thoracic and visceral sites, had higher fasting plasma insulin and C-peptide, and tended to have higher fasting triglyceride and lower HDL cholesterol than men with normal glucose tolerance. Women with IGT had more thoracic subcutaneous fat and intra-abdominal fat and lower fasting HDL cholesterol than women with normal glucose tolerance, and tended to have higher fasting triglyceride and LDL cholesterol. Women with IGT also had higher fasting plasma insulin than women with normal glucose tolerance but tended to be less hyperinsuli-naemic than men. Differences in fasting insulin, C-peptide, and lipids were best predicted by intra-abdominal fat. Thus metabolic (higher fasting insulin and a tendency to higher triglyceride and lower HDL cholesterol) and adipose (visceral adiposity) risk factors associated with the insulin resistance syndrome are identifiable among Sansei men and women with IGT, who may therefore be at increased risk of future development of NIDDM and CHD.