Elevated liver enzymes in individuals with undiagnosed diabetes in the U.S.

OBJECTIVE: We investigated the association of diabetes diagnosis and medication type with liver injury in individuals with clinical diabetes.
METHODS: We analyzed 2426 patients with clinical diabetes in the National Health and Nutrition Examination Survey conducted from 1999 to 2008. Elevated alanine transaminase (ALT) and aspartate transaminase (AST) levels were used as markers of liver injury. Participants were categorized into one of three categories: 1) clinical diabetes without physician's diagnosis or diabetes medication; 2) diagnosed diabetes without diabetes medication; or 3) diagnosed diabetes with diabetes medication, further divided by classes of diabetes medications prescribed. We conducted logistic regression analysis to examine the relationship between diabetes diagnosis and medication type and elevated ALT and AST, adjusting for race/ethnicity, education, health insurance status, BMI category, alcohol consumption, physical activity, antihyperlipidemic agents, glycohemoglobin, C-reactive protein, viral hepatitis and liver disease.
RESULTS: Participants with undiagnosed diabetes were more likely to have elevated ALT and AST levels (OR=1.82, 95% CI 1.47, 2.42; OR=1.99, 95% CI 1.46, 2.71, respectively). In contrast, there was no association between specific diabetes medication (i.e., sulfonylureas, biguanides/thiazolidinediones) and elevated ALT or AST levels among the treated. Our findings were confirmed in sensitivity analyses employing a lower threshold for ALT, and excluding individuals with viral hepatitis or liver disease.
CONCLUSION: We found that undiagnosed diabetes is associated with liver injury, compared to diagnosed diabetes with treatment. The effect of diabetes treatment on liver injury in individuals with diabetes remains uncertain.