Study reveals inverse relationship between vitamin D levels and HbA1c in individuals with Type 2 diabetes

India: Vitamin D plays a vital role in insulin sensitivity and glucose metabolism; therefore, its deficiency can contribute to the development and progression of type 2 diabetes mellitus (T2DM), a recent study has concluded.

The study revealed a negative correlation between vitamin D levels and glycosylated hemoglobin (HbA1c) levels in type 2 diabetes. However, the researchers suggest that this correlation can be recovered by vitamin D therapy, which helps control glycemic levels. The study is scheduled for publication in the July-September issue of Apollo Medicine and is now available online ahead of its print release.

"Our study reveals a noteworthy inverse relationship between vitamin D levels and HbA1c in individuals with Type 2 diabetes. In simpler terms, higher vitamin D levels are linked to better blood sugar control," Dr. Rinki Kumari, Department of Advanced Centre for Traditional and Genomic Medicine, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India, told Medical Dialogues.

Vitamin D, crucially acquired through sunlight exposure and dietary sources like fatty fish and fortified foods, faces widespread deficiency, especially in regions with limited sunlight or dietary diversity. In individuals with diabetes, the role of Vitamin D in glucose metabolism is intricate, impacting insulin sensitivity and secretion mechanisms within the pancreas. Deficiency in this vitamin is linked to serious health conditions, including cardiovascular disease, diabetes, cancers, and multiple sclerosis (MS).

Dr. Kumari et al. aimed to investigate the correlation between Vitamin D levels and HbA1c in patients with type 2 diabetes and healthy controls.

The study enrolled 163 individuals with T2DM (Group I) and 174 healthy subjects (Group II). Using radioimmunoassay and high-performance liquid chromatography, researchers measured Vitamin D and HbA1c levels in the blood serum.

The study led to the following findings:

• Group I, comprised of T2DM patients, exhibited significantly lower Vitamin D levels (17.82 ± 2.23 ng/mL) than Group II. Correspondingly, T2DM patients also showed higher HbA1c levels, indicative of poorer glycemic control, which was statistically significant.

• Further analysis within Group I demonstrated a negative correlation between Vitamin D and HbA1c levels.

• Combining the data from both groups reinforced the inverse relationship, indicating that lower Vitamin D levels were associated with higher HbA1c levels across the study population.

The findings revealed a high prevalence of Vitamin D deficiency in Group I. Additionally, identifying a negative relationship between Vitamin D levels and HbA1c levels is a significant discovery. Vitamin D is well-recognized for its pivotal role in glucose metabolism and insulin sensitivity, suggesting that its insufficiency may contribute to the onset and progression of T2DM.

Dr. Rinki added, “From a public health perspective, promoting vitamin D supplementation and encouraging safe sun exposure could help prevent diabetes complications and support overall health."

"What sets this study apart is its examination of both diabetic and nondiabetic individuals, providing a broader perspective on how vitamin D levels impact overall metabolic health. By comparing these two groups, the study offers new insights into the potential role of vitamin D in managing diabetes and enhancing general health. This comprehensive approach could pave the way for new strategies in diabetes care, integrating vitamin D assessment and management into routine healthcare practices," Dr. Kumari pointed out.

While recommending 2000 IU of cholecalciferol daily for 16 weeks serves as a reasonable starting point for clinicians, it is crucial to evaluate each individual’s Vitamin D status, medical history, and potential drug interactions before making recommendations. A personalized approach to Vitamin D supplementation is essential to ensure safety and effectiveness, the study stated.

According to Dr. Kumari, one limitation of this study is that it is observational, meaning it cannot definitively prove that low vitamin D causes poor blood sugar control. Additionally, the relatively small sample size might limit the applicability of the results to the broader population.

"Future research should focus on conducting long-term, interventional studies to determine if vitamin D supplementation can improve HbA1c levels. Expanding the research to include a more diverse group of participants would also help to confirm and extend these findings," she concluded.

Citation:

Shukla J, Singh A, Sachan N, Verma RS, Kumari R, Dubey GP, et al. Evaluation of correlation between the level of Vitamin D and glycosylated hemoglobin in type 2 diabetic mellitus and nondiabetic mellitus. Apollo Med 2024; https://doi.org/10.1177/09760016241238855