Research Spotlight: Sex Differences in Insulin Sensitivity are Related to Muscle Tissue Acylcarnitine But Not Subcellular Lipid Distribution

Posted on April 26, 2021

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"Sex Differences in Insulin Sensitivity are Related to Muscle Tissue Acylcarnitine But Not Subcellular Lipid Distribution"

Diabetes is a serious health concern for many people across the globe. Approximately 34 million people in the U.S. currently have type 2 diabetes. Diabetes is also known to affect the male population at a higher rate than the female population likely due to the higher prevalence of insulin resistance in males. Males are also known to have a generally lower body fat percentage than women suggesting that insulin resistance is more closely related to body fat distribution than overall body fat.

Initial reports have suggested that an increased level of intramuscular triglyceride (IMTG) was associated with insulin resistance in people with obesity. Recently, reports indicate that males have a lower insulin sensitivity as well as lower concentrations of IMTG in muscle tissue which refutes this association. Furthermore, new evidence supports the role of accumulation of certain lipids within muscle rather than total lipid content. The study reported below aimed to evaluate lipid contributors to differences in insulin sensitivity between men and women with obesity.

Researchers used Avanti products for their lipidomics analysis. Serum ceramide and sphingolipids were analyzed using Avanti’s Synthetic Sphingolipid Standards. So, what did the lipidomics analysis reveal? The study was consistent with previous studies and concluded that males do have lower insulin sensitivity than females. They also reported that lower insulin sensitivity is not due to subcellular localization but instead may be related to alterations in muscle acylcarnitine, serum ceramide, and lysophosphatidylcholine (LPC).

The study found that total and long-chain acylcarnitines in muscle remained higher in obese males after insulin stimulation when compared to obese females. Acylcarnitines have previously been linked to insulin resistance. The results also revealed that the circulating lipids, serum ceramide, and LPC, potentially influence sex-based differences in insulin sensitivity. Serum ceramides are elevated in patients with obesity and type 2 diabetes and are related to insulin resistance and inflammation. The report observed higher serum ceramides in obese men than women. LPC is another possible contributor, but previous research regarding the involvement of LPC levels and their association with insulin sensitivity has been inconclusive. The research found that acylcarnitines were most strongly related to the difference in the level of insulin sensitivity between males and females.

A better understanding of the mechanisms of insulin resistance in men and women has implications which could help save and better lives across the world by targeting insulin sensitivity in a sex-dependent manner. This is just another example of amazing work being done by Avanti’s lipid products.

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