BACKGROUND: In vitro and animal experiments have shown inhibiting effects of angiotensin receptor blockers (ARBs) on the formation of advanced glycation end products (AGEs), which are known to be involved in the development of cardiovascular complications in diabetes. However, sufficient human data to confirm such beneficial effects of ARBs on AGEs are lacking. Therefore, we investigated the effects of irbesartan treatment on plasma levels of the AGEs N(epsilon)(1-carboxymethyl)lysine (CML) and N(epsilon)(1-carboxyethyl)lysine (CEL) in hypertensive patients with type 2 diabetes and microalbuminuria. METHODS: We analysed data from a multicentre, double-blind, parallel, randomized controlled trial in patients with type 2 diabetes and microalbuminuria, the primary goal of which was to examine the renoprotective effects of irbesartan treatment (150 or 300 mg daily). Secondary end points included plasma CML and CEL in the treatment arm receiving 300 mg irbesartan (n = 139) and in the placebo group (n = 125). Effects of treatment at 1- and 2-year follow-up were analysed by means of generalized estimating equations according to an intention-to-treat principle. RESULTS: Levels of CML and CEL did not differ between groups at baseline. No significant changes were observed in CML and CEL over time in either group and there was no effect of treatment on CML and CEL at any time-point. Mean differences for the irbesartan versus placebo group over time were -0.96 mumol/mol lysine (95% confidence interval: -3.43 to 1.51) for CML and -0.10 mumol/mol lysine (-0.76 to 0.56) for CEL. CONCLUSIONS: Long-term irbesartan treatment does not influence plasma levels of the AGE CML and CEL in patients with type 2 diabetes and microalbuminuria.