Association of Vitamin B12 and Vitamin D Levels with Glycemic Control in Patients with Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) is a growing global health concern, especially in low- and middle-income countries like India. Optimal glycemic control remains a cornerstone of diabetes management in primary care. Emerging evidence suggests that micronutrient deficiencies, particularly vitamin B12 and vitamin D, may adversely affect glucose metabolism and insulin sensitivity, yet their routine assessment is often overlooked in clinical practice.

To evaluate the association between serum vitamin B12 and vitamin D levels with glycemic control in patients with T2DM and to explore their potential as modifiable risk factors in primary care-based diabetes management.

This cross-sectional study enrolled 500 patients with T2DM attending the outpatient clinic of Shyam Shah Medical College, Rewa, in 2024. Data collected included demographics, BMI, HbA1c, fasting and postprandial glucose, vitamin B12, 25-hydroxyvitamin D, lipid profile, and renal function tests. Patients were categorized based on glycemic control (Group A: HbA1c < 7%, Group B: HbA1c ≥ 7%). Statistical analyses included t-tests, Pearson correlation, and multivariate regression.

Group A had significantly higher vitamin B12 (674.2 ± 609.5 pg/mL) and vitamin D levels (31.20 ± 13.80 ng/mL) compared to Group B (457.76 ± 463.6 pg/mL and 26.76 ± 20.63 ng/mL, respectively; P < 0.01). HbA1c showed inverse correlations with both vitamins. Multivariate analysis confirmed both as independent predictors of glycemic control.

Vitamin B12 and D deficiencies are significantly associated with poor glycemic control and may serve as modifiable targets in diabetes care, warranting routine screening in primary care settings.