Introduction: Diabetes mellitus represents a rapidly escalating global public health issue and is a principal cause of morbidity and mortality due to its acute and chronic complications. Alterations in mineral metabolism, particularly magnesium deficiency, have been implicated in the pathogenesis and progression of type 2 diabetes mellitus. Magnesium is integral to glucose metabolism and insulin action; however, studies investigating the relationship between serum magnesium levels and glycemic control in diabetes have yielded inconsistent results. Aim: To ascertain the prevalence of hypomagnesemia in patients with type 2 diabetes mellitus and to evaluate its association with glycemic control. Methodology: A cross-sectional observational study was conducted among 150 patients with type 2 diabetes mellitus attending the outpatient department, casualty, or admitted to various wards of the Department of General Medicine at Sree Mookambika Institute of Medical Sciences, Kanyakumari, Tamil Nadu, from March 2024 to September 2025. Results: Among the 150 diabetic patients, 39 cases (26%) exhibited hypomagnesemia. The hypomagnesemia and normomagnesaemia groups were comparable in terms of age and sex distribution. The mean HbA1c level was significantly higher in the hypomagnesemia group compared to the normomagnesaemia group. Conclusion: The prevalence of hypomagnesemia among Indian patients with type 2 diabetes mellitus is substantial. Hypomagnesemia is positively associated with poor glycemic control. Keywords: Diabetes mellitus; Glycemic control; Hypomagnesemia

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