One-hour post-load plasma glucose levels are associated with elevated liver enzymes

Background and aims: Glucose-tolerant subjects who have 1-h post-load glucose levels ≥155 mg dl(-1) (normal glucose tolerance (NGT)-1h-high) are at an increased risk of developing type 2 diabetes. Prospectively conducted studies indicated that high levels of liver enzymes are predictors of a tendency to develop type 2 diabetes; however, it is unknown whether the NGT-1h-high subjects are at increased risk for secreting higher levels of liver biomarkers.

Methods and results: In this study, oral glucose tolerance tests (OGTTs) were performed in a cohort of 1000 non-diabetic Caucasians and levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gamma-glutamyltransferase (GGT) were measured in these subjects. The NGT-1h-high subjects had increased levels of ALT and GGT, but not AST, as compared with the NGT-1h-low. Following adjustment for age and gender, the ALT, AST and GGT levels were all found to be significantly correlated with body mass index (BMI), waist circumference, blood pressure, triglycerides as well as fasting and post-challenge glucose and insulin levels. In a logistic regression analysis adjusted for age and gender, NGT-1h-high subjects were found to be at increased risk of having ALT levels in the highest quartile as compared with NGT-1h-low subjects (odds ratio (OR) = 1.71; 95% confidence interval (CI): 1.16-2.52). In addition, NGT-1 h-high subjects exhibited an increased risk for having GGT levels in the highest quartile (OR = 1.50; 95%CI: 1.02-2.17). These associations remained significant after adjustment for BMI, blood pressure and lipids, but were not significant following further adjustment for an insulin sensitivity index. NGT-1h-high subjects were at increased risk of having AST levels in the highest quartile as compared with NGT-1h-low subjects (OR = 1.51; 95%CI: 1.04-2.22). This association ceased to be significant following adjustment for BMI, blood pressure and lipids.

Conclusions: These data suggest that a 1hPG ≥ 155 mg dl(-1) cut-off may facilitate the identification of NGT individuals at risk of developing liver abnormalities.