Minimal Model-Derived Insulin Sensitivity Index Underestimates Insulin Sensitivity in Black Americans

OBJECTIVE To examine the ethnic differences in insulin sensitivity (S-I) as measured by the minimal model approach (S-I-MM) and the reference method, the euglycemic-hyperinsulinemic clamp (EHC). RESEARCH DESIGN AND METHODS In a prospective study design, thirty Black Americans (BA) were age, sex, and BMI matched with non-Hispanic Whites (NHW). Participants underwent frequently sampled intravenous tolerance test (FSIVGTT) and EHC on 2 separate days during a single visit. RESULTS S-I-MM values were significantly lower in BA when compared with NHW (0.035 +/- 0.025 vs. 0.058 +/- 0.036 [dL/min]/[mu U/mL]; P = 0.003). However, there were no ethnic differences in S-I measured by EHC (0.028 +/- 0.012 vs. 0.035 +/- 0.019 [dL/min]/[mu U/mL]; P = 0.18). CONCLUSIONS S-I-MM systematically underestimates S-I in BA when compared with NHW. These findings suggest that studies inferring lower S-I in BA based on FSIVGTT and S-I-MM should be interpreted cautiously.