Study of Vitamin D and Serum Calcium Levels in Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) is a growing global health concern. Emerging evidence suggests that vitamin D and calcium play an important role in glucose metabolism and insulin function. The present study aimed to compare serum vitamin D and calcium levels between patients with T2DM and healthy controls and evaluate their association with glycaemic control (HbA1c).

This hospital-based case-control study included 136 participants, comprising 68 patients with T2DM and 68 healthy controls. Serum vitamin D and calcium levels were estimated, along with fasting blood sugar (FBS), postprandial blood sugar (PPBS), and glycated haemoglobin (HbA1c). Vitamin D and calcium status were categorized using standard cut-offs. Statistical analysis was performed using an independent t-test, chi-square test, and Pearson correlation.

Glycaemic parameters were significantly higher in diabetic patients, including FBS (149.7 ± 51.0 vs. 87.2 ± 14.2 mg/dL), PPBS (223.5 ± 77.3 vs. 123.5 ± 17.6 mg/dL), and HbA1c (9.4 ± 2.1% vs. 5.1 ± 0.4%) (p = 0.001). Serum calcium (8.3 ± 0.7 vs. 9.0 ± 0.6 mg/dL) and vitamin D (20.23 ± 9.07 vs. 25.21 ± 8.23 ng/mL) were significantly lower in diabetics (p = 0.001). Vitamin D deficiency was more prevalent in diabetic patients (34 (50.0%) vs. 20 (29.4%); p = 0.038), and hypocalcaemia was also significantly higher (38 (55.9%) vs. 18 (26.5%); p = 0.001). Serum vitamin D (r = -0.412, p = 0.001) and calcium (r = -0.356, p = 0.002) showed significant negative correlation with HbA1c.

Patients with T2DM have significantly lower serum vitamin D and calcium levels, which are associated with poor glycaemic control. Assessment of vitamin D and calcium status may help identify micronutrient abnormalities in patients with T2DM; however, interventional studies are required to determine clinical benefit.