ASSOCIATION BETWEEN VITAMIN D DEFICIENCY AND GLYCEMIC CONTROL IN TYPE 2 DIABETES PATIENTS

Abstract

Background: Type 2 Diabetes Mellitus (T2DM) remains a worldwide epidemic, with glycemic control serving as the cornerstone of care to prevent microvascular and macrovascular complications. This study aims to investigate the association between baseline vitamin D deficiency and changes in glycemic control parameters (particularly HbA1c and fasting blood glucose).

Methods: A prospective cohort study was conducted with 200 type 2 diabetes mellitus patients who visited Sarosh Hospital and Diagnostic Center, Muzaffarabad, Azad Jammu and Kashmir, Pakistan. Patients were divided into two groups at baseline based on their blood 25-hydroxyvitamin D (25(OH)D) levels: deficient (<20 ng/mL) and insufficient/sufficient (≥20 ng/mL). HbA1c and fasting plasma glucose (FPG) levels were measured at baseline, 3 monthsm and 6 months to assess glycemic management. Throughout the observation period, all patients maintained their usual anti-diabetic regimens without protocol-driven vitamin D administration to test the natural association. The statistical study used repeated measures ANOVA and multivariate regression to control for confounding variables like age, body mass index (BMI), and baseline HbA1c.

Results: Among the 200 patients (mean age 54.7 ± 9.2 years; 52% male), 112 (56%) were vitamin D deficient at baseline. The deficient group had significantly higher mean HbA1c levels at baseline (8.4% ± 1.1%) than the non-deficient group (7.6% ± 0.9%) (p < 0.001). During the 6-month follow-up, the deficient group observed poor glycemic control, with HbA1c increasing to 8.7% ± 1.2%, whereas the non-deficient group remained stable (7.7% ± 1.0%). There was a strong negative association with HbA1c change at 6 months (r= -0.42, p <0.001). After controlling for age, gender, BMI, and baseline anti-diabetic medication use, multivariate regression analysis revealed that baseline vitamin D deficiency was an independent predictor of impaired glycemic progression (β = 0.35, p= 0.002).

Conclusion: Vitamin D deficiency is common among type 2 diabetes mellitus patients and is independently associated with poorer glycemic control and a progressive worsening of HbA1c over 6 months. These findings show that screening for and treating vitamin D deficiency could be an important adjuvant technique in diabetes care.