Serum electrolyte levels in relation to macrovascular complications in Chinese patients with diabetes mellitus

Background: The prevalence of diabetes in China is increasing rapidly. However, scarce data are available on serum electrolyte levels in Chinese adults with diabetes, especially in those with cardiovascular complications. This study measured serum electrolyte levels and examined their relationship with macrovascular complications in Chinese adults with diabetes. Methods: The three gender-and age-matched groups were enrolled into this analysis, which were 1,170 subjects with normal glucose regulation (NGR), 389 with impaired glucose regulation (IGR) and 343 with diabetes. Fasting plasma glucose (FPG), 2-hour post-load plasma glucose (2hPG), glycosylated hemoglobin A1c (HbA1c) and serum electrolyte levels were measured. Data collection included ankle brachial index results. Results: Serum sodium and magnesium levels in the diabetes group were significantly decreased compared to the NGR group (sodium: 141.0 +/- 2.4 vs. 142.1 +/- 2.0 mmol/l; magnesium: 0.88 +/- 0.08 vs. 0.91 +/- 0.07 mmol/l, all P < 0.01), while the serum calcium level was significantly increased (2.36 +/- 0.11 vs. 2.33 +/- 0.09 mmol/l, P < 0.01). Multiple linear regression showed that serum sodium and magnesium levels in the diabetes group were negatively correlated with FPG, 2hPG and HbA1c (sodium: Std beta = -0.35, -0.19, -0.25; magnesium: Std beta = -0.29, -0.17, -0.34, all P < 0.01), while the serum calcium level was positively correlated with HbA1c (Std beta = 0.17, P < 0.05). In diabetic subjects, serum sodium, magnesium and potassium levels were decreased in the subjects with the elevation of estimated glomerular filtration rates (P < 0.05). ANCOVA analysis suggested that serum magnesium level in subjects with diabetic macrovascular complications was significantly decreased compared with diabetic subjects without macrovascular complications after the effect of some possible confounding being removed (P < 0.05). Conclusions: Serum sodium and magnesium levels were decreased in Chinese subjects with diabetes, while the observed increase in calcium level correlated with increasing glucose level. Diabetic patients with macrovascular complications had lower serum magnesium level than those with no macrovascular complications.