Myths vs facts: HDL and blood sugar

HDL (high-density lipoprotein) is often called 'good cholesterol,' but its relationship with blood sugar is more nuanced than common myths suggest. Myth: Higher HDL automatically lowers diabetes risk. Fact: Epidemiological studies show an inverse correlation between HDL and type 2 diabetes, but causal evidence is lacking. HDL may promote insulin secretion and have anti-inflammatory effects, yet genetic variants (e.g., in CETP) that raise HDL do not reduce diabetes risk – some even suggest increased risk. Myth: HDL levels above 60 mg/dL are always optimal. Fact: Very high HDL (>80 mg/dL in men, >100 mg/dL in women) can indicate dysfunctional HDL and is associated with higher mortality. For blood sugar, HDL function (cholesterol efflux, antioxidant capacity) matters more than concentration. Lifestyle factors like exercise, Mediterranean diet, and moderate alcohol can raise HDL and also improve blood sugar – the benefit likely stems from lifestyle, not HDL itself. Caveat: No HDL-raising drugs are recommended for diabetes prevention. Evidence: mixed – epidemiological associations but conflicting intervention and Mendelian randomization studies.