Correlation of Plasma Magnesium with Insulin Resistance in Type 2 Diabetes: A Cross-sectional Study from South-Western Nigeria

Introduction: Insulin resistance (IR) is a core component of the pathophysiology of type 2 diabetes mellitus (DM). Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) is the most commonly used marker of IR. Plasma magnesium is a relatively cheap analyte and has been linked with the pathophysiology of IR. This study primarily was aimed at evaluating the possible use of plasma magnesium as a surrogate marker of IR in type 2 diabetes. Materials and Methods: The study was a hospital-based cross-sectional study carried out at a tertiary hospital in South-western Nigeria between March and September 2018. The study was conducted on 70 persons with diabetes, and age- and sex-matched 70 controls who met the eligibility criteria were recruited into the study. Ethical approval was obtained and informed consent was obtained from the participants. Fasting plasma glucose, fasting plasma insulin, and plasma magnesium were measured using standard protocols. HOMA-IR was determined using the appropriate formula. Data analysis was carried out using the Statistical Package for Social Sciences software, (SPSS) version 22. Results: The mean age of the participants was 53.34 +/- 9.57 years and that of the gender-matched controls was similar. Frequency of hypomagnesemia was significantly higher in the participants compared with controls (25.7% vs. 5.7%; P < 0.001). Similarly, a significantly greater proportion of the study participants (62.9%) had IR as expected compared with just 8.7% of the controls. The mean plasma magnesium (mg/dL) among the participants was significantly lower than that of the controls (1.73 +/- 0.16 vs. 1.87 +/- 0.14; P < 0.001). As expected, the mean HOMA-IR in the participants was significantly higher than that of the controls (2.64 +/- 0.91 vs. 1.71 +/- 0.32; P<0.001). There was a statistically significant negative correlation between plasma magnesium and IR among the participants (r=-0.443; P<0.001). However, among the controls, there was no statistically significant correlation between plasma magnesium and HOMA-IR (r=-0.034; P = 0.778). Conclusion: Plasma magnesium was found to correlate significantly with IR and may be used as a surrogate marker of IR in persons with type 2 DM but not in the general population.