Effect of oral vitamin D and calcium replacement on glycaemic control in South Asian patients with type 2 diabetes

Background: Vitamin D deficiency is associated with a greater risk of developing type 2 diabetes mellitus (T2DM). Studies looking at the effect of vitamin D replacement on glycaemic control in type 2 diabetics are few and conflicting. In addition, none have been published looking at the South Asian population despite both T2DM and vitamin D deficiency being gross burdens in this population. The aim of this study was to determine the effect of using vitamin D and calcium replacement therapy on glycaemic control in South Asian patients with T2DM and vitamin D inadequacy. Materials and Methods: Data were collected retrospectively from patients’ records focusing on South Asians with established T2DM treated with combined oral vitamin D₃ and calcium supplementation. Vitamin D, parathyroid hormone (PTH), HbA1c and weight were recorded before and after 3 months on this therapy. Results: Post‐treatment, all patients’ (n = 52) vitamin D levels were normalised (> 50nmol/l). There was a mean decrease in HbA1c of 0.70 ± 0.77% (p < 0.001) in the vitamin D deficient group (n = 29) and 0.21 ± 0.28% (p = 0.001) in the vitamin D insufficient group (n = 23). The change in weight post‐treatment was only significant in the vitamin D deficient group at ?0.80 ± 1.11 kg (p = 0.001). Overall, there were negative correlations between the changes in HbA1c and weight with the change in vitamin D (p < 0.05). Conclusion: This study shows that vitamin D and calcium replacement therapy in South Asian patients with T2DM causes a significant decrease in both HbA1c and weight, which may be attributed to the increase in vitamin D levels post‐treatment.