INS and diabetes mellitus: Other studies showed that magnesium supplementation improves the insulin resistance index and beta cell function and reduces hemoglobin A1c (HbA1c) levels in patients with type 2 diabetes mellitus (Rodrı ́guez-Mora ́n and Guerrero-Romero, 2003; Guerrero-Romero and Rodrı ́guez-Mora ́n, 2011).