Altered skeletal muscle lipid metabolism is a hallmark feature of type 2 diabetes (T2D). Here we investigated muscle lipid turnover in T2D versus BMI-matched controls and examined if putative in vivo differences would be preserved in the myotubes.
Male obese T2D individuals (T2D) (n=6) and their BMI-matched controls (C) (n=6) underwent a hyperinsulinemic-euglycemic clamp, VO2max test, DXA scan, underwater weighing and muscle biopsy of v. lateralis. 14C-palmitate and 14C-oleate oxidation rates and incorporation into lipids were measured in muscle tissue, as well as in primary myotubes.
Palmitate oxidation (C: 0.99 ± 0.17, T2D: 0.53 ± 0.07nmol/mg protein; P=0.03) and incorporation of fatty acids (FAs) into triacylglycerol (TAG) (C: 0.45 ± 0.13, T2D: 0.11 ± 0.02nmol/mg protein; P=0.047) were significantly reduced in muscle homogenates of T2D. These reductions were not retained for palmitate oxidation in primary myotubes (P=0.38); however, incorporation of FAs into TAG was lower in T2D (P=0.03 for oleate and P=0.11 for palmitate), with a strong correlation of TAG incorporation between muscle tissue and primary myotubes (r=0.848, P=0.008).
Our data indicate that the ability to incorporate FAs into TAG is an intrinsic feature of human muscle cells that is reduced in individuals with T2D.
- Received July 19, 2013.
- Accepted January 24, 2014.
- © 2014 by the American Diabetes Association.
Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered. See http://creativecommons.org/licenses/by-nc-nd/3.0/ for details.