Evidence check: HDL in the context of blood sugar

The relationship between HDL cholesterol and blood sugar is complex. HDL is often called 'good' cholesterol, but its role in glucose metabolism is not fully understood. Epidemiological studies show that low HDL levels are associated with increased risk of insulin resistance and type 2 diabetes. However, HDL is not a direct marker for blood sugar or diabetes. HDL may have anti-inflammatory and antioxidant properties that could theoretically improve insulin sensitivity. But causal evidence from randomized trials is lacking. Drugs that raise HDL have not shown consistent improvement in blood sugar control. Therefore, the utility of HDL as a biomarker for blood sugar is limited. The evidence is mainly based on observational studies and mechanistic reasoning. For a comprehensive assessment of blood sugar risk, fasting glucose, HbA1c, and possibly an oral glucose tolerance test are more appropriate. HDL should not be interpreted in isolation.