Relationship Between Serum Magnesium Levels and Glycemic Control in Type 2 Diabetes Mellitus: A Case-Control Study

Introduction: Type 2 diabetes mellitus (T2DM) is a prevalent metabolic disorder that represents a global health burden.Recent findings indicate that serum magnesium plays a crucial role in glucose metabolism and insulin function.Insufficient magnesium levels are associated with diminished insulin secretion and increased insulin resistance.However, region-specific data from South India, particularly Kerala, remain limited.Materials and methods: A case-control study was conducted in the Department of Medicine of a tertiary care hospital in Kerala from November 2022 to March 2024 to compare serum magnesium levels between adults with uncontrolled and controlled T2DM and to assess the associations of serum magnesium levels with HbA1c and other clinical and biochemical variables.A total of 34 patients with uncontrolled T2DM (HbA1c >7%) and 34 patients with controlled T2DM (HbA1c ≤7%), classified according to the 2021 American Diabetes Association glycemic target guidelines, were matched by age and sex.Demographic and laboratory data were analyzed using SPSS Statistics version 25 (IBM Corp. Released 2017.IBM SPSS Statistics for Windows, Version 25.0.Armonk, NY), with p < 0.05 considered statistically significant.Results: Demographic characteristics were similar across groups.Uncontrolled cases had significantly higher HbA1c (median 8.3%, IQR 7.83-9.0vs 6.7%, IQR 6.5-6.9;p < 0.001), fasting blood sugar (median 187.5, IQR 142-204 vs 120 mg/dL, IQR 110.25-131.75;p < 0.001), and blood pressure than controls.Hypomagnesemia occurred only in patients with uncontrolled T2DM (5/34, 14.7%); median serum magnesium was significantly lower in cases than in controls (2.1, IQR 1.9-2.3vs 2.3 mg/dL, IQR 2.1-2.3;p = 0.018).Within cases, serum magnesium correlated inversely with triglycerides (ρ = -0.417,p = 0.014) but not significantly with HbA1c (ρ = -0.196,p = 0.266).Conclusions: Serum magnesium was lower in uncontrolled than in controlled T2DM, with hypomagnesemia only in the uncontrolled group.Within cases, magnesium correlated inversely with triglycerides but not significantly with HbA1c.Causality cannot be established given the design; larger prospective and interventional studies are needed.