Eating nuts may help to combat Type 2 diabetes, research suggests.

Two servings of tree nuts a day appears to lower and stabilise blood sugar levels in people with the disease, according to evidence collected from 12 clinical trials.

Tree nuts include most nut types, including walnuts, cashews, hazelnuts and pecans, but exclude peanuts, which are technically legumes.

Nut consumption improved two key markers of blood sugar, the results from analysing data on 450 trial participants showed.

One, the HbA1c test, measures blood sugar levels over three months. The other, the fasting glucose test, assesses blood sugar after the patient has not eaten for eight hours.

The best results were seen when nuts replaced refined carbohydrates rather than saturated fats.

A single serving of tree nuts was defined as about a quarter of a cup, or 30 grams. Participants in the clinical trials were given 56 grams of nuts a day on average.

John Sievenpiper, from St Michael’s Hospital in Toronto, Canada, who led the study, said: “Tree nuts are another way people can maintain healthy blood sugar levels in the context of a healthy dietary pattern.”

He pointed out that while nuts are high in fat, the fat is of the healthier unsaturated variety.

Despite the fact that nuts can be high in calories, participants in the clinical trials did not gain weight.