The dietary calcium-to-magnesium ratio and its association with glycemic control in type 2 diabetes: a cross-sectional study.

Inadequate magnesium (Mg) and calcium (Ca) intake has been associated with impaired glucose homeostasis in type 2 diabetes mellitus (T2DM). An imbalanced dietary Ca/Mg ratio may affect the concentrations of these nutrients and contribute to poor disease control. This study investigated the association between the dietary Ca/Mg ratio, serum Ca and Mg levels, and glycemic biomarkers in individuals with T2DM. A cross-sectional observational study was conducted in adults with T2DM. Body weight, height, waist circumference, blood pressure, body fat percentage, and body mass index were assessed. Dietary Ca and Mg intake was evaluated, and the Ca/Mg ratio was calculated. Plasma Ca and Mg were measured by inductively-coupled plasma optical emission spectrometry. Fasting glucose, glycated hemoglobin, C-peptide, parathyroid hormone, and indices of insulin resistance (HOMA-IR), β-cell function (HOMA-%B), and insulin sensitivity (HOMA-%S) were assessed. Participants were stratified according to dietary Ca/Mg ratio (≤ 2 and > 2). Mann-Whitney or Student's t tests, Pearson's chi-square test, and linear regression analyses were performed (p < 0.05). Of 115 individuals evaluated, 74% were females, with a median age of 49 years and median T2DM duration of 6 years. All participants had inadequate Mg intake (median dietary Ca/Mg ratio: 2.3). A lower dietary Ca/Mg ratio was correlated with higher HOMA-%S (p = 0.049), whereas a higher ratio correlated with higher HOMA-IR (p = 0.05) and C-peptide levels (p = 0.008). Furthermore, a higher dietary Ca/Mg ratio was associated with lower insulin sensitivity (β = - 4.588, p = 0.038). An imbalance between Mg and Ca levels was associated with greater insulin resistance in individuals with T2DM.