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 D(3) 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.