Diabetes drugs warning: they cause heart problems

Widely used diabetes drugs appear to increase patients' risk of potentially fatal heart problems, according to a study conducted by researchers from Imperial College London and published in the British Medical Journal.

Researchers examined patient and prescription records to examine rates of heart failure, heart attack and death from any cause among 900,000 patients taking all different kinds of diabetes drugs. Patients were followed for an average of seven years each.

Diabetes drugs fall into three classes: sulphonyureas, glitazones and biguanides. The sulphonyureas include chlorpropamide, glibenclamide (marketed as Daonil and Euglucon), gliclazide (marketed as Diamicron), glimepiride (marketed as Amaryl), glipizide (marketed as Glibenese and Minodiab) and tolbutamide. The glitazones, also called thiazolidinediones, include rosiglitazone (marketed as Avandia) and pioglitazone (marketed as Actos). Metformin is the only anti-diabetes biguanide on the market.

The researchers compared all other drugs to metformin, which is an older, well-proven diabetes drug that is often used as a first line of treatment. They found that patients taking sulphonyureas were between 24 and 60 percent more likely to die of any cause than patients taking metformin, and also significantly more likely to suffer heart failure or heart attack. Patients on rosiglitazone had an increased risk of heart failure over metformin.

Pioglitazone appeared to offer the same risk of heart failure as metformin, and both glitazones had the same risk of heart attack or death as the older drug.

Because the elevated blood sugar levels characteristic of diabetes tend to damage blood vessels, all diabetics are at an increased risk of heart attacks and strokes. Combined with the fact that chronic conditions such as cardiovascular disease can take a long time to develop even when caused or exacerbated by drugs, this means that heart-related side effects to diabetes drugs can be very hard to detect. Often, they only emerge after products have been on the market for years.