Changes in liver tests during 1-year treatment of patients with Type 2 diabetes with pioglitazone, metformin or gliclazide.

Aims: Patients with Type 2 diabetes are at increased risk of liver damage. Therefore, it is of particular importance to investigate the hepatic effects of drugs used to treat such patients.

Methods: Liver testing results performed in four 1-year, randomized, double-blind studies comparing effects of pioglitazone, metformin or a sulphonylurea, gliclazide, in the treatment of over 3700 patients with Type 2 diabetes have been analysed.

Results: Pioglitazone caused reductions in mean levels of hepatic enzymes of between 3 and 18%, whilst gliclazide caused small increases of between 3 and 13%. Metformin treatment showed either small mean increases or decreases. More patients receiving pioglitazone had liver tests within the normal range at the end of treatment (> or = 87%) compared with patients receiving metformin (> or= 80%) or gliclazide (> or = 75%). Slightly fewer patients with pioglitazone than with comparators showed a large increase (> 3 upper limit of normal) in alanine aminotransferase levels at any time during treatment (pioglitazone 0.9%, metformin 1.9%, gliclazide 1.9%).

Conclusions: During pioglitazone treatment there is a reduction in liver enzyme levels. Although the mechanism of this effect is not clear, the results demonstrate potential beneficial effects on the liver during treatment of patients with Type 2 diabetes with pioglitazone.