Correlation between HDL cholesterol levels and beta-cell function in subjects with various degree of glucose tolerance

Some reports showed direct effects of high density lipoprotein cholesterol (HDL-C) on beta-cells survival and insulin secretion, suggesting an its role on glucose metabolism. We queried, whether subjects screened for type 2 diabetes (DM2) could display some impairment of beta-cell performance related to their HDL-C levels. A total of 1,087 clinical outpatients at risk of DM2 with no history of diabetes were studied. All participants were assessed for anthropometry, fasting lipid profile, and 2hOGTT with blood samples for plasma glucose and insulin determinations. Matsuda index of insulin sensitivity, early (insulinogenic index × Matsuda) and total (insulin secretion-sensitivity index-2 [ISSI-2]) indices of beta-cell function OGTT derived were applied. Linear regression analyzed the association between HDL-C levels and indices of beta-cell activity in subjects with normal glucose tolerance (NGT), impaired fasting glycemia (IFG), and impaired glucose tolerance (IGT). After adjustment for triglyceride levels, waist circumference, blood pressure and age, in total NGT subjects the HDL-C levels were not significantly associated with IGI × Matsuda (β = 0.039, P = 0.10) and ISSI-2 index (β = 0.069, P = 0.18), while in NGT with low HDL-C and IFG subjects the IGI × Matsuda (β = 0.052, P = 0.019) and ISSI-2 indices (β = 0.061, P = 0.023) were significantly associated with HDL-C levels. This significant linear correlation has been also observed in IGT patients for both indices (β = 0.264, P = 0.0001 and β = 0.191, P = 0.002, respectively). In conclusion, in subjects with impaired glucose regulation, HDL-C levels are associated with indices of beta-cell dysfunction; thus, more attention, it should be deserve to HDL-C concentrations in IFG/IGT patients due their potential conversion to DM2.