Reduced Serum Magnesium Levels Are Associated with the Occurrence of Retinopathy in Patients with Type 2 Diabetes Mellitus: a Retrospective Study.

The aim of this study is to explore the relationship between serum magnesium (Mg2+) level and diabetic retinopathy (DR) in patients with type 2 diabetes mellitus (T2DM). The clinical data of 2222 patients with T2DM, including 713 patients with DR and 1509 patients without DR, between September 2016 and August 2020 in our hospital, were analyzed retrospectively. Further, the role and predictive value of serum Mg2+ on the prevalence of DR were determined through logistic regression and the receiver operating characteristic (ROC) curve respectively. The level of serum Mg2+ was lower in DR group than that in non-DR group (0.92 vs 0.88 mmol/L, P < 0.001). Stratified serum Mg2+ levels into quartiles (Q1-Q4), the first (Q1, Mg2+ ≤ 0.85 mmol/L) and fourth quartile (Q4, ≥ 0.96 mmol/L) represented the lowest and highest quartile, respectively. And the incidence of DR was obviously higher in Q1 and Q2 than that in Q3 and Q4 (50.9% and 30.2% vs 23.5% and 21%, respectively). Logistic regression demonstrated that there remained an independent association between lower serum Mg2+ levels and the occurrence of DR (OR were 3.907 and 1.709 in Q1 and Q2, respectively) no matter whether the interference of confounding variables. ROC curve showed the best cut-off value of serum Mg2+ level in predicting the occurrence of DR was 0.875 mmol/L. Lower Mg2+ levels are related with an increased risk of developing DR. Serum Mg2+ level can be a potential clinical indicator to help identify DR in patients with T2DM.