Leptin, hs-CRP and HOMA-IR in patients with type 2 diabetes: The role of different levels of vitamin D deficiency

Background: To evaluate the effects of different levels of vitamin D deficiency on blood glucose, leptin, high sensitivity C-reactive protein (hs-CRP), and insulin resistance and their associations. Methods: We quantified serum vitamin D level, hs-CRP, leptin, and fasting blood sugar (FBS) levels in 25 type-2 diabetic patients with deficient serum levels of 25-hydroxy vitamin D (<= 15 ng/ml) and 25 type-2 diabetic patients with insufficient serum levels of 25-hydroxy vitamin D (16 to 30 ng/ml). The two groups were matched according to age, sex, and body mass index (BMI). Homeostasis model assessment of insulin resistance (HOMA-IR) was calculated by a formula based upon values of FBS and insulin concentrations. Results: The mean value of vitamin D levels was 7.67 +/- 3.10 in the vitamin D deficient group and 23.20 +/- 9.97 in the vitamin D insufficient group. Patients with vitamin D deficiency had significantly higher FBS, postprandial glucose (PPG) and hemoglobin A1C (HbA1C) as compared to vitamin D insufficient group (p<0.01). We studied correlations of hs-CRP, HOMA-IR, and leptin in both vitamin D insufficient and deficient groups. There were significant positive correlations between leptin with hs-CRP (r = 0.58, p<0.01) and with HOMA-IR (r = 0.49, p<0.05) in vitamin D deficient group. These correlations remained significant after multiple adjustment for age, sex, BMI, systolic and diastolic blood pressure. Conclusion: In conclusion, vitamin D deficient diabetic patients had elevated FBS, PPG and HbA1C compared with insufficient ones. The results also could possibly point the effect of vitamin D deficiency level on leptin associations with hs-CRP and insulin resistance.