Abstract P295: Association of Intermuscular Fat Density with Hyperinsulinemia and Insulin Resistance

Background: Emerging evidence indicates that ectopic fat, such as that in the visceral depot or muscle fat infiltration, may be associated with diabetes, independent of general obesity.Very little is known about the health effects of fat density, an emerging novel indicator of fat quality. Existing studies have focused on visceral or pericardial fat density. There is currently no information on muscle fat density and its associations with diabetes or other cardio-metabolic disorders. Methods: The aim of this preliminary study was to investigate whether visceral (VAT) or intermuscular (IMAT) adipose tissue density was associated with measures of glucose and insulin homeostasis independent of fat depot volume. We hypothesized that adipose tissue characterized by higher density would be associated with lower glucose and insulin fasting serum levels, and lower homeostasis model assessment of insulin resistance (HOMA-IR). Adipose tissue volume (cm3) and density (Hounsfield units) were measured in the abdomen and thigh from computed tomography scans in 193 non-diabetic black men aged 50 to 87 years (mean age 61 years, mean BMI 27 kg/m2). All measures were transformed to normal distribution and partial Pearson correlation coefficients were calculated. Results: In models adjusted for age and corresponding fat volume, thigh IMAT density and abdominal paraspinal IMAT density were inversely associated with fasting insulin (=-0.15 and r=-0.16, respectively; both p<0.05) and HOMA-IR (r=-0.18 and r=-0.19, respectively; both p<0.05). These associations were only slightly attenuated after additional adjustment for BMI (p for all <0.07). In contrast, VAT density was not associated with fasting insulin or HOMA-IR after adjustment for VAT volume or BMI. No fat density measure was associated with fasting serum glucose in any model. Conclusion: We found a novel correlation between lower intermuscular fat density and hyperinsulinemia and insulin resistance among non-diabetic black men. These results suggest that muscle fat quality may be a novel predictor of diabetic risk even independent of overall and ectopic fat volume.