Glucose tolerance and cardiovascular risk in young adult African Americans

Patients with type 2 diabetes have higher rates of cardiovascular events. Among African Americans, there is a higher prevalence of both cardiovascular disease and type 2 diabetes. Few studies have examined longitudinally the change in glucose tolerance in younger adult African Americans.

To examine the longitudinal relationship of glucose tolerance with other cardiovascular risk factors, 30 African American men and women aged 20 to 43 years were examined twice at an interval of 4 to 5 years. Cardiovascular risk factors, glucose tolerance, and insulin sensitivity (determined from euglycemic hyperinsulinemic clamp procedure) were assessed at each examination. Known diabetics were excluded from initial enrollment. The relationship of glucose tolerance status (normal, impaired, or diabetic glucose tolerance) to body mass index, blood pressure, cholesterol, and insulin sensitivity were further investigated.

Initial oral glucose tolerance test identified 24 of 130 (18.5%) subjects with impaired glucose tolerance and 2 of 130 (1.5%) subjects with diabetes. Of the remaining 104 subjects with normal glucose tolerance, subsequent 5-year examination detected 31 (29.8%) with impaired glucose tolerance and 5 (4.8%) with diabetes. Those who later developed diabetes had higher mean systolic blood pressure (133 versus 121, P = 0.037) at exam 1. By exam 2, those with abnormal glucose tolerance had worse cardiovascular risk profiles and increased insulin resistance (P < 0.001).

Conversion to abnormal glucose tolerance is relatively frequent in young adult African Americans. Deterioration in glucose tolerance may be preceded by higher systolic blood pressure and is accompanied by worsening of other cardiovascular risk factors and insulin resistance.