The association between magnesium and diabetic retinopathy: a cross-sectional study

To investigate the clinical significance of serum magnesium in non-diabetic mellitus (non-DM), diabetes mellitus (DM) and diabetic retinopathy (DR). Moreover, to assess magnesium concentration in DR mice models.

Baseline data from 150 patients per group (non-DM, DM, DR) comprised demographics, cardiovascular-metabolic profiles, electrolytes, and systemic immune-inflammatory were collected and analyzed. Logistic regression analysis was used to screen influencing factors for DR. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the diagnostic utility of hemoglobin A1c (HbA1c) and magnesium. Magnesium concentration in both serum and retinal tissues of DR mice were quantified via the methylthymol blue assay.

Compared with the non-DM group, the DM group had lower age and blood pressure levels (P < 0.05), while heart rate, HbA1c and serum phosphorus levels were significantly higher (P < 0.05). Serum sodium and magnesium levels decreased gradually across the non-DM, DM and DR groups (P < 0.05), whereas heart rate and HbA1c levels increased progressively in the three groups (P < 0.05). Compared with DM, those with DR had longer diabetic duration. Ordinal multinomial logistic regression among non-DM, DM and DR groups indicated that HbA1c was positively associated with DR risk, whereas magnesium was negatively correlated with DR. Binary logistic regression between DM and DR groups showed that diabetes duration, SBP and HbA1c were positively related to elevated DR risk, and magnesium was negatively associated with the occurrence of DR. The ROC curve analysis revealed that a combined diagnostic of HbA1c and serum magnesium, with cut-off value of 0.500, achieved a sensitivity of 78.7% and a specificity of 90.0% for DM. The combined diagnosis of HbA1c and magnesium, with cut-off value of 0.441, approached a sensitivity of 75.3% and a specificity of 66.0% for DR. DR mice exhibited lower magnesium levels in both serum and retinal tissues compared with the control mice (P < 0.05).

Patients with DR had longer disease duration, elevated HbA1c levels and decreased serum magnesium concentrations. Combined detection of serum magnesium and HbA1c can significantly improve the diagnostic performance of DR.