Higher magnesium levels are associated with better glycaemic control and diabetes remission post-bariatric surgery.

Background: Low Magnesium (Mg) dietary intake has been associated with increased risk of type 2 diabetes mellitus (T2DM). Furthermore, in patients with T2DM, hypomagnesemia is associated with worst glycaemic control. Bariatric surgery (BS) remains the most effective treatment in severe obesity and also provides resolution/improvement of T2DM. Our aim is to evaluate the association between Mg supplementation post-BS and Mg serum levels with diabetes status after BS.

Methods: We performed an observational study on patients with obesity and T2DM who underwent BS. Data was assessed pre-BS and one-year post-BS.

Results: We included a total of 403 patients with T2DM. At baseline, 43.4% of the patients had Mg deficiency. Pre-BS, patients with Mg deficiency had poorer glycaemic control - HbA1c 7.2 ± 1.6% vs 6.4 ± 1.0% (p < 0.001), fasting plasma glucose 146.2 ± 58.8 mg/dL vs 117.5 ± 36.6 mg/dL (p < 0.001) and were under a greater number of anti-diabetic drugs 1.0 (IQR 0-2.0) vs 1.0 (IQR 0-1.0) (p = 0.002). These findings persisted at one-year post-BS. At the first-year post-BS, 58.4% of the patients had total remission of T2DM and 4.1% had partial remission. Patients without Mg deficiency at one-year post-BS had higher rates of total and partial remission. Higher serum Mg levels at baseline is an independent predictor of total T2DM remission (p < 0.0001). The optimal cut-off of baseline Mg to predict total T2DM remission was 1.50 mg/dL with a sensitivity of 73% and a specificity of 58% (area under ROC = 0.65). Patients that were under Mg supplementation post-BS had serum Mg values, glycaemic control and total remission of T2DM similar to patients non-supplemented.

Conclusion: In patients with T2DM submitted to BS, higher Mg serum levels at baseline and 1-year after BS were associated with better glycaemic control and higher rates of total T2DM remission at the first year post-BS.