Objective: We had previously shown two variants among black non-insulin-dependent diabetic (NIDDM) subjects in a normoglycemic remission: one with insulin resistance and the other with normal insulin sensitivity. This study examined whether these two variants exist in the ordinary hyperglycemic black NIDDM population.
Research design and methods: Fifty-two black NIDDM subjects were assessed for insulin-stimulated glucose disposal (euglycemic clamp), glycemic control (fasting plasma glucose and HbA1c), and fasting lipid profiles.
Results: The distribution of glucose disposal in 30 black NIDDM subjects (body mass index; BMI less than 30 kg/m2) was bimodal, which indicated two populations. Eighteen of 30 subjects (BMI 26.4 +/- 0.5 kg/m2) had insulin resistance (glucose disposal 3.21 +/- 0.24 mg.kg-1.min-1). Twelve of 30 subjects (BMI 24.83 +/- 1.1 kg/m2) had normal insulin sensitivity (glucose disposal 7.19 +/- 0.46 mg.kg-1.min-1). Twenty-one of the remaining 22 subjects (BMI 33.4 +/- 0.7 kg/m2) were insulin resistant (glucose disposal 2.88 +/- 0.21 mg.kg-1.min-1). Fasting serum triglyceride levels were lowest in the insulin-sensitive population (0.91 +/- 0.07 mM) and different from the insulin-resistant population, BMI less than 30 and greater than 30 kg/m2, (1.20 +/- 0.10 mM, P less than 0.05 and 1.42 +/- 0.17 mM, P less than 0.025, respectively). Fasting serum low-density lipoprotein cholesterol levels were not significantly different among the groups, although it did increase with insulin resistance and increasing obesity. Total serum cholesterol levels and glycemic control were similar for all three groups. Serum high-density lipoprotein cholesterol levels were higher in women compared with men.
Conclusions: In the hyperglycemic black NIDDM population, two variants exist: one with insulin resistance and one with normal insulin sensitivity. This insulin-sensitive variant represents 40% of subjects with a BMI less than 30 kg/m2. Moreover, the insulin-sensitive group has a lower risk profile for cardiovascular disease.