# Association of Vitamin D Deficiency With Glycemic Control in Type 2 Diabetes Mellitus

## TL;DR

This study shows that low vitamin D levels are linked to worse blood sugar control in people with type 2 diabetes.

## Contribution

The study provides new evidence that vitamin D deficiency is associated with higher HbA1c levels in type 2 diabetes patients.

## Key findings

- Vitamin D deficiency was present in 68.3% of the patients with type 2 diabetes.
- Deficient patients had significantly higher HbA1c, fasting glucose, and insulin resistance compared to sufficient patients.
- A negative correlation was found between serum vitamin D levels and HbA1c.

## Abstract

Background

Insulin secretion and glucose metabolism are influenced by vitamin D. Deficiency can lead to a decrease in insulin sensitivity and a deterioration in glycemic control.

Objectives

This study’s objective is to examine the association between serum vitamin D and glycemic control (HbA1c) among patients with type 2 diabetes mellitus (T2DM).

Methods

We studied 120 patients with T2DM. The measurement of vitamin D (25-hydroxyvitamin D (25(OH)D)) and HbA1c used established methods. Deficiency was classified as having a level of vitamin D < 20 ng/mL.

Results

Mean age was 52.6 ± 9.4 years; 70/120 (58.3%) were male. Vitamin D deficiency was present in 82/120 (68.3%). Mean HbA1c was higher in deficient vs sufficient patients (8.4 ± 1.2% vs 7.6 ± 1.0%, t = 3.82, p = 0.002). Fasting plasma glucose and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) were also higher in the deficient group (p ≤ 0.01). Serum vitamin D correlated negatively with HbA1c (r = −0.34, p = 0.001).

Conclusion

Vitamin D deficiency was common and associated with poorer glycemic control. Screening and treatment of deficiency may aid metabolic outcomes in T2DM.