Accumulation of saturated intramyocellular lipid is associated with insulin resistance.

Intramyocellular lipid (IMCL) accumulation has been linked to both insulin-resistant and insulin-sensitive (athletes) states. Biochemical analysis of intramuscular triglyceride composition is confounded by extramyocellular triglycerides in biopsy samples, and hence the specific composition of IMCLs is unknown in these states. H magnetic resonance spectroscopy (MRS) can be used to overcome this problem. Thus, we used a recently validated H MRS method to compare the compositional saturation index (CH:CH) and concentration independent of the composition (CH) of IMCLs in the soleus and tibialis anterior muscles of 16 female insulin-resistant lipodystrophic subjects with that of age- and gender-matched athletes ( = 14) and healthy controls ( = 41). The IMCL CH:CH ratio was significantly higher in both muscles of the lipodystrophic subjects compared with controls but was similar in athletes and controls. IMCL CH:CH was dependent on the IMCL concentration in the controls and, after adjusting the compositional index for quantity (CH:CH), could distinguish lipodystrophics from athletes. This CH:CH marker had a stronger relationship with insulin resistance than IMCL concentration alone and was inversely related to VO The association of insulin resistance with the accumulation of saturated IMCLs is consistent with a potential pathogenic role for saturated fat and the reported benefits of exercise and diet in insulin-resistant states.