Association of Serum Magnesium Levels with Diabetic Retinopathy in Patients with Type 2 Diabetes Mellitus: A Cross-Sectional Study

Background: Diabetic retinopathy is a common microvascular complication of type 2 diabetes mellitus (T2DM). Magnesium is important for insulin action, glucose metabolism, and vascular function, and low levels may contribute to diabetic complications. Evidence from Bangladesh is limited. This study aimed to assess the association between serum magnesium levels and diabetic retinopathy in patients with T2DM. Methods: This was a hospital-based cross-sectional study, conducted at department of medicine and ophthalmology, Shaheed Suhrawardy Medical College Hospital, Dhaka from 25th April to 24th October 2016. A total 100 adult patients with T2DM were enrolled using purposive sampling method. Sociodemographic and clinical data were collected using a structured questionnaire. All participants underwent comprehensive ophthalmological examination by an ophthalmologist for the diagnosis of diabetic retinopathy. Serum magnesium categorized as hypomagnesaemia (<1.8 mg/dL), normomagnesaemia (1.8–2.4 mg/dL), or hypermagnesaemia (>2.4 mg/dL). The association between serum magnesium levels and diabetic retinopathy was analyzed using independent t-test and assessed correlation between duration of T2DM and serum magnesium using Pearson’s correlation. A p-value <0.05 was considered statistically significant Results: The mean age of participants was 57.08 ± 6.78 years, with males comprising 61% of the study population. Diabetic retinopathy was present in 73% of patients. Hypomagnesaemia was observed in 57% of participants, making it the most common magnesium status. Patients with diabetic retinopathy had significantly lower mean serum magnesium levels compared to those without retinopathy (1.50 ± 0.18 mg/dL vs. 1.65 ± 0.11 mg/dL; p = 0.014). A significant negative correlation was observed between duration of diabetes mellitus and serum magnesium levels (r = -0.62; p= 0.015). Conclusions: Lower serum magnesium levels were significantly associated with diabetic retinopathy among patients with T2DM. Hypomagnesaemia may represent a modifiable associated biomarker for diabetic retinopathy. Further prospective and interventional studies are required to establish causality.