Eating a cup of beans or lentils every day may help people with type 2 diabetes control their blood sugar and possibly reduce their risk of heart attacks and stroke, according to a Canadian study.

Researchers, whose results appeared in the Archives of Internal Medicine, found that compared with a diet rich in wholegrains, getting a daily dose of legumes led to small drops in an important measure of blood sugar as well as in blood pressure and cholesterol levels.

After three months on the bean diet, study participants’ estimated 10-year risk of cardiovascular disease had fallen from 10.7 per cent to 9.6 per cent, according to the group.

Legumes such as beans, chickpeas and lentils, are already recommended for diabetics due to their low Glycemic Index (GI), a measure of how far and how fast a given food sends up blood sugar. But there are few studies of their direct effects on diabetes, according to David Jenkins.

Jenkins of St Michael’s Hospital in Toronto, who led the study, and his team divided 121 people with diabetes into two groups: one was instructed to up their intake of cooked legumes by at least a cup a day; the other was told to eat more wholewheat products to boost their fibre intake.

After three months, the researchers found that haemoglobin A1c levels had dropped from 7.4 per cent to 6.9 per cent in people eating beans, while it had fallen from 7.2 per cent to 6.9 per cent in those getting extra wholewheat.

The number reflects the average blood sugar levels over the previous two to three months. Experts recommend keeping it under seven per cent.