Higher intramuscular triacylglycerol in women does not impair insulin sensitivity and proximal insulin signaling

Research output: Contribution to journalJournal articleResearchpeer-review

Women have been shown to have higher muscle tricylglycerol (IMTG) levels than men and could therefore be expected to have lower insulin sensitivity than men, since previous studies have linked high IMTG to decreased insulin sensitivity. Thus, insulin sensitivity of whole body and leg glucose uptake was studied in 9 women in the follicular phase and 8 men on a controlled diet and matched for maximal oxygen uptake per kg lean body mass and habitual activity level. A 47% higher (p<0.05) muscle triacylglycerol (IMTG) level was found in women than men and at the same time women also displayed 22% higher whole body (p<0.05) and 29% insulin stimulated leg glucose uptake (p=0.05) during an euglycemic-hyperinsulinemic ( approximately 70 uU/ml) clamp compared to matched male subjects. The higher insulin sensitivity in women could not be explained by higher expression of muscle GLUT4, insulin receptor (IR) or Akt expression or the ability of insulin to stimulate Akt (thr308) or Akt (ser473) phosphorylation. However, a 30% higher (p<0.05) capillary density and 31% more type 1 muscle fiber expressed pr. area in the vastus lateralis muscle were noted in women than in matched males. It is concluded that despite 47% higher IMTG levels in women in the follicular phase whole body as well as leg insulin sensitivity are higher than in matched men. This was not explained by sex differences in proximal insulin signalling in women. In women it seems that a high capillary density and type 1 muscle fiber expression may be important for insulin action. Key words: Muscle Triglycerides, gender, insulin action, sex paradox.
Original languageEnglish
JournalJournal of Applied Physiology
Pages (from-to)824-831
Number of pages8
Publication statusPublished - 2009

ID: 14023553