Taking the blood thinner warfarin in conjunction with sulfonylureas (SUs) has been found to increase the risk of hospitalisation for hypoglycaemia in a large study of Medicare recipients in the US.
This retrospective cohort analysis identified 71 895 people who received prescriptions both for warfarin and for the second-generation SUs glipizide or glimepiride. Compared with 394 023 people who received SUs only, the rate of hospitalisation for hypoglycaemia was significantly higher (adjusted odds ratio [OR], 1.22; 95% confidence interval [CI], 1.05–1.42).
Combination therapy was also associated with a higher rate of hospitalisation for fall-related fractures, (OR, 1.47; 95% CI, 1.41–1.54) and altered consciousness or mental status (OR, 1.22; 95% CI, 1.16–1.29).
The authors recognise that, as that all their participants were aged ≥65 years, their findings may not be generalisable to younger populations. Notwithstanding this limitation, they conclude that there is a significant interaction between warfarin and SUs. Although several clinical drug databases note that such an interaction may occur, healthcare professionals are not routinely alerted when people with type 2 diabetes on SUs start treatment with warfarin.
While the authors believe that warfarin remains safe to prescribe in people who are receiving SUs, they recommend that such patients should be closely monitored, especially when starting on the new treatment.
The study can be read in full in the BMJ here.
