Association between serum vitamin D and insulin resistance in type 2 diabetes mellitus

Abstract

Vitamin D deficiency is an increasingly recognized yet poorly addressed metabolic risk factor that may aggravate insulin resistance in patients with type 2 diabetes mellitus (T2DM), thereby worsening glycemic control and long-term outcomes. Therefore, it is of interest to examine the association between serum 25-hydroxyvitamin D [25(OH)D] levels and markers of insulin resistance including the Homeostatic Model Assessment of Insulin Resistance (HOMA-IR), fasting insulin, fasting blood glucose and HbA1c in 120 patients with confirmed T2DM. Serum vitamin D levels were significantly lower in patients with higher HOMA-IR values, with a strong inverse correlation observed between serum vitamin D and HOMA-IR (r = −0.72, p<0.001). The prevalence of insulin resistance (HOMA-IR >2.5) was 92.9% in severely deficient patients compared to 20.0% in those with sufficient vitamin D levels. Thus, data shows the clinical importance of routine vitamin D assessment in T2DM patients as a potentially modifiable target to reduce insulin resistance and improve glycemic outcomes.