Drug-induced bullous pemphigoid in diabetes mellitus patients receiving dipeptidyl peptidase-IV inhibitors plus metformin

Background Preclinical data and reports of adverse skin reactions in patients treated with dipeptidyl peptidase-IV inhibitors (gliptins) have increased awareness towards skin-targeting side-effects of these anti-hyperglycaemic drugs. Bullous pemphigoid (BP), sometimes drug-induced, is the most commonly acquired autoimmune blistering dermatosis in western countries, typically a disease of the elderly people with significant morbidity and excess mortality. Objective To report the development of BP in five diabetics under gliptin (4 vildagliptin, 1 sitagliptin) plus metformin in fixed-dose drug combinations. Case reports From March to August 2010 six out of nine newly diagnosed BP patients in our Department were type 2 diabetics. Five of them were on gliptin plus metformin (three different trade preparations) for 2-13 months prior to BP onset. In all cases BP was controlled after withdrawal of the suspected medication and relatively mild therapeutic interventions. In two cases the eliciting role of the preceding treatment is supported by evidence at the level 'probable/likely' according to the WHO-UMC algorithm. Conclusions This is the first report of drug-induced BP as a group adverse event of the gliptins plus metformin combination therapy for glycaemia control in type 2 diabetes mellitus patients.