Serum magnesium in diabetic retinopathy: the association needs investigation

Magnesium has an essential role in glucose metabolism, and hypomagnesaemia is common in diabetes mellitus. However, the relationship between serum magnesium and diabetic retinopathy is poorly understood.

To determine the association between serum magnesium levels and retinopathy in type 2 diabetic patients with normal renal function and to correlate it with severity of retinopathy.

This cross-sectional observational study was conducted in a semi-urban tertiary-care teaching hospital. Clinicodemographic profile and serum magnesium levels were determined in patients with type 2 diabetes mellitus (DM) with (group 1) and without (group 2) retinopathy. Serum magnesium levels were correlated with the presence and severity of retinopathy.

Of 104 type 2 DM patients, 50 had retinopathy. Younger age, longer duration of disease and poorer glycaemic control (p < 0.05) were found to be associated with retinopathy. The mean serum magnesium levels in patients with retinopathy and those without retinopathy were 1.63 ± 0.30 mg/dL and 1.76 ± 0.22 mg/dL, respectively (p = 0.029). Reduced serum magnesium was associated with elevated fasting sugars (p = 0.019) and female gender (p = 0.037). On comparative analysis of patients with sight-threatening diabetic retinopathy (STDR), non-STDR and no retinopathy by ANOVA test, patients with STDR had significantly lower serum magnesium (1.55 ± 0.33 mg/dL) (p = 0.031).

Serum magnesium levels were lower in patients with diabetic retinopathy. Patients with STDR had lower serum magnesium compared with those without STDR.

Serum magnesium, studied extensively for its role in glucose metabolism, was found to be lower in patients with diabetic retinopathy compared with those without retinopathy. Sight-threatening diabetic retinopathy had significantly lower levels of serum magnesium.