Impact of the Glycemic Control and Duration of Type 2 Diabetes on Vitamin D Level and Cardiovascular Disease Risk

Abstract

Background and Aims. To investigate the impact of glycemic control and T2D duration on vitamin D status and cardiovascular disease (CVD) risk among Saudi patients. Methods. This case-control study was conducted in King Faisal Specialist Hospital, Saudi Arabia. A total of 25 nondiabetic controls and 92 patients with confirmed T2D, aged 20-60 years, were included. Patients with T2D were divided into the following groups based on disease duration (newly diagnosed: ≈6 months and long duration: ≥5 years) and glycemic control based on their glycated hemoglobin (HbA1C) level with a threshold of ≤0.053 mol/mol: newly diagnosed controlled (NC, n=25), newly diagnosed uncontrolled (NU, n=17), long duration controlled (LC, n=25), and long duration uncontrolled (LU, n=25). Blood levels of fasting blood glucose, HbA1C, lipid profile, and serum 25-hydroxyvitamin D (25(OH)D) were assessed and used to define the CVD risk score. Results. Our study showed that T2D duration was an independent predictor of vitamin D deficiency. The longer disease duration, the lower odds of being vitamin D deficient (odds ratio (OR) = 0.05, 95% CI: 0.01-0.29, p<0.05). No significant association was observed between vitamin D and HbA1C levels. In the NU group, CVD risk scores were directly correlated with serum 25(OH)D (r=0.53, p<0.05). On the contrary, 25(OH)D was moderately inversely correlated with CVD risk score in the LU group (r=-0.45, p<0.05). Conclusion. Duration of diabetes rather than glycemic control is associated with vitamin D deficiency. Glycemic uncontrol may augment vitamin D deficiency-associated CVD risk in both newly diagnosed and old patients with type 2 diabetes.