Hypomagnesemia, insulin resistance, and non-alcoholic steatohepatitis in obese subjects.

BACKGROUND: Epidemiological evidence shows a strong relationship between decreased serum magnesium levels (DSML) and insulin resistance. As nonalcoholic steatohepatitis (NASH) seems to be related to insulin resistance, the aim of this study was to determine the potential relationship between DSML and NASH in obese subjects.

METHODS: We compared obese individuals with the diagnosis of diabetes, insulin-resistance, and non-insulin resistance to a control group of non-obese, non-insulin-resistant subjects. Participants were required to have negative viral markers and negligible alcohol intake. Other liver diseases and well-known causes for decreasing of magnesium were exclusion criteria. A liver biopsy was performed in subjects with aspartate aminotransferase (AST) and alanine aminotransferease (ALT) levels > or =40 IU/mL.

RESULTS: Of the 60 obese subjects, 20 were non-insulin resistant, 20 were insulin resistant, and 20 were type 2 diabetics. Twenty subjects were in the control group. Eleven (33.3%) diabetics, 14 (42.4%) insulin-resistant subjects, and 8 (24.2%) non-insulin-resistant subjects underwent liver biopsies. Diagnosis of NASH was established in 29 (36.2%) individuals. Subjects with the diagnosis of NASH exhibited lower serum magnesium levels of 1.7 +/- 0.2 mg/dL (0.70 +/- 0.08 mmol/L), and those with fibrosis showed the lowest serum magnesium concentration at 1.5 +/- 0.3 mg/dL (0.62 +/- 0.12 mmol/L). Multiple regression analysis adjusted by age showed that low serum magnesium concentration was independently related to a high HOMA-IR index (OR 7.6, CI 95% 2.1-11.2; p <0.0001) and that a high HOMA-IR index was related to NASH (OR 6.5, CI 95% 1.5-8.8; p <0.01). After adjusting for age and a high HOMA-IR index, hypomagnesemia remained independently related to NASH (OR 1.4, CI 95% 1.1-5.4; p <0.05).

CONCLUSIONS: The results of this study demonstrate an independent relationship between DSML and NASH.