Serum magnesium in diabetic retinopathy: relation to glycated haemoglobin and lipid profile

The aim of this study was to evaluate serum magnesium status in diabetic retinopathy and to investigate its relation to serum lipid profile and glycated haemoglobin (HbA١c) as a marker for longterm metabolic control in diabetes. The current case control study has enrolled ٢٥ type ٢ diabetics without retinopathy (Group ١), ٢٥ diabetics with retinopathy (Group ٢) and ٢١ apparently healthy nondiabetic control subjects (Group ٣). Overnight fasting serum magnesium, lipid profile and HbA١c concentration were analyzed for all subjects. The mean serum magnesium level was significantly lower in Group (٢) compared to that of Group ١ (p< ٠.٠٠١). The mean serum triglycerides (TGs) and HbA١c levels were significantly higher in Group ٢ (p< ٠.٠٠٠١). No statistically significant differences were noticed comparing the mean serum total cholesterol (TC) and LDL-cholesterol concentrations in both groups ١ and ٢ (p> ٠.٠٥). The study revealed a significant negative correlation between serum magnesium on one hand and serum TGs, TC, LDLcholesterol and HbA١c on the other hand where r= ٠.٦٤٦, ٠.٤٧, ٠.٣٣٥, and ٠.٨٢٥ respectively. Meanwhile serum magnesium was significantly and positively correlated with HDLcholesterol levels (r= ٠.٣٩٥, p> ٠.٠٠١). Using Forward Stepwise Multiple Regression analysis, the study revealed that hypomagnesaemia, poor glycaemic control and increasing duration of diabetes are the most important contributors to the cumulative risk for the development of diabetic retinopathy (Odds ratios ١٦.٦٥, ٥٦٦ and ٧.٣٦ respectively). In conclusion, magnesium depletion is a significant risk factor for, and a frequent finding in, diabetic retinopathy beside poor glycaemic control, dyslipidaemia (mainly hypertriglyceridaemia), and increasing duration of uncontrolled diabetes. The significant association between hypomagnesaemia and high fasting serum levels of TGs, TC, LDL-cholesterol and HbA١c would rather support the suggested role for magnesium depletion in the metabolic derangements associated with retinopathy in diabetic patients. Further studies on the effects of magnesium supplementation for diabetic patients are necessary to investigate the spectrum of metabolic improvements following magnesium therapy and the degree to which the risk of diabetic retinopathy might be reduced.