The Relationship Between the Sex-Based Difference in Insulin Sensitivity and Acylcarnitine

Diabetes is a threat to health of many people around the world. As males are vulnerable to insulin resistance, diabetes is likely to affect the males at a higher rate than the females. In addition, males have a lower body fat percentage than females indicating that insulin resistance is more closely related to body fat distribution than overall body fat.

Previously, the study demonstrated that the increased level of intramuscular triglyceride (IMTG) was related to insulin resistance in people with obesity. However, a recent study refuted such idea, suggesting that males have a lower insulin sensitivity and lower IMTG concentrations in muscle tissues. Moreover, the new evidence showed that rather than total lipid content, the accumulation of certain lipids play a key role in muscle. The study aimed to evaluate lipid factors contributed to the differences in insulin sensitivity between males and females with obesity.

By analyzing serum ceramide and sphingolipids, researchers concluded that males have lower insulin sensitivity than females. They also reported that the lower insulin sensitivity is not caused by subcellular localization, but may be related to the alterations in muscle acylcarnitine, serum ceramides and lysophosphatidylcholine (LPC).

The study suggested that compared to the females with obesity, the males with obesity have higher total and long-chain acylcarnitines in muscle after insulin stimulation. Acylcarnitines have previously been linked to insulin resistance. The result also revealed that the circulating lipids, serum ceramides and LPC might 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. LPC is another possible factor. However, the study regarding the involvement of LPC levels and their association with insulin sensitivity is still uncertain. The research found that acylcarnitines were the 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 could help target insulin sensitivity in a sex-dependent manner.

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