Insulin sensitivity and intramyocellular lipid concentrations in young Maori men

In muscle, resistance to insulin-mediated glucose uptake is thought to underlie the pre-Type 2 diabetic condition. In European Caucasian men, insulin sensitivity is negatively associated with intramyocellular lipid (IMCL) content, and this may provide an early marker of diabetes risk. This study was designed to examine the relationship between vastus lateralis IMCL content, aerobic fitness, adiposity and markers of insulin sensitivity in healthy, young Maori men.

The following parameters were measured in 24 Maori men aged 28 +/- 6 years (mean +/- sd): overnight fasting blood concentrations of glucose, insulin and triglycerides; body composition using underwater weighing; maximal oxygen uptake (VO2max) using an incremental treadmill exercise test; and vastus lateralis IMCL concentration using proton nuclear magnetic resonance spectroscopy (1H MRS).

All participants had normal fasting blood glucose. Simultaneous multiple regression analysis with homeostasis model assessment-insulin resistance (HOMA-IR) as the dependent variable showed that: (i) increased body fatness and decreased aerobic capacity (per kg lean body mass) are significant predictors of insulin sensitivity as estimated by HOMA-IR; and (ii) although vastus lateralis IMCL concentrations are elevated, they do not contribute to the prediction of insulin sensitivity.

IMCL is not a reliable marker of estimated insulin resistance in this cohort of young, healthy Maori men. However, measures of composition and aerobic fitness may be of use as non-invasive, culturally acceptable measures to help identify Maori men with impaired insulin action, but normal fasting glycaemia.