Serum vitamin D status and its relationship with insulin resistance amongst a cohort of Nigerian patients with type 2 diabetes mellitus

Abstract

Abstract Background: Insulin resistance (IR) is a cardinal pathophysiological mechanism for the development of type 2 diabetes mellitus (T2DM). Vitamin D has been proposed to play an important role in the pathogenesis of T2DM. The aim of this study was to evaluate the relationship between serum levels of vitamin D and IR among persons with T2DM in a tertiary health facility in Southern Nigeria. Materials and Methods: The study was a comparative cross-sectional study conducted at the medical outpatient clinic of a hospital in Nigeria. Participants included 120 patients with T2DM and 60 healthy controls. Levels of serum vitamin D, fasting insulin, and fasting plasma glucose were determined. IR was determined using the homeostasis model assessment of IR (HOMA-IR). Data obtained were analyzed with Statistical Package for Social Sciences, version 22. Results: The mean serum vitamin D of the subjects with T2DM was significantly lower than the controls (35.84 ± 11.65 ng/mL vs. 44.71 ± 20.12 ng/mL; P < 0.001). The median HOMA-IR of the T2DM subjects was significantly higher than that of controls (2.26 [2.57] vs. 1.59 [1.53]; P = 0.002). The mean serum vitamin D was significantly higher among T2DM participants with HOMA-IR of less than 2 compared with participants who had HOMA-IR of greater than or equal to 2 (39.80 ± 13.22 ng/mL vs. 33.91 ± 9.75 ng/mL; P < 0.05). There was a significant negative correlation between serum vitamin D and HOMA-IR among patients with T2DM (P < 0.001). Conclusion: The finding of this study could signify that vitamin D levels may be used as a surrogate marker of IR.