Background

Greater values HOMA-IR and Adipose tissue Insulin Resistance (ADIPO-IR) indicate insulin resistance with regards to glucose and free fatty acid (FFA) metabolism. We sought to determine whether some adults are discordant for HOMA and ADIPO-IR and, if so, what are the defining features.

Methods

We collated data from 466 volunteers who participated in 19 IRB-approved studies between 1995 and 2010. Plasma triglyceride, FFA-palmitate, glucose an insulin concentrations, as well as body composition (DXA and abdominal CT) and basal metabolic rate (BMR) were measured. Sex-specific quartiles of HOMA-IR and ADIPO-IR were created. We identified those in the top and bottom quartiles of HOMA-IR, but the middle 2 quartiles of ADIPO-IR (HHMA, n = 25 and LHMA, n = 30, respectively), as well as those in the top and bottom quartiles of ADIPO-IR, but the middle 2 quartiles of HOMA-IR (MHHA, n = 26, and MHLA, n = 30, respectively). Residual BMR was calculated as the difference between measured BMR and that predicted from this population specific sample based upon fat free mass, body fat, sex and age.

Results

The HHMA group differed from the LHMA group in terms of BMI (27.2±3.8 vs. 23.4±3.1, P<0.001), body fat (32±11 vs. 25±10%, P=0.02) and residual BMR (-77±160 vs. +48±199 Kcal/day, P=0.002), respectively. The MHHA group differed from the MHLA group in terms of visceral (129±93 vs. 68±78 cm2, P=0.004) and abdominal subcutaneous (189±119 vs. 116±106 cm2, P=0.02) fat, as well as fasting serum triglyceride concentrations (118±48 vs. 87±26 mg/dL, P=0.01), respectively.

Conclusions

Those with disproportionately high HOMA-IR have more body fat, but surprisingly lower BMR, whereas those with disproportionately high ADIPO-IR have more abdominal fat and greater fasting triglyceride concentrations. These findings suggest that there are subpopulations of insulin resistance that may have unique and unexplained metabolic profiles.