Increasing the proportion of foods rich in monounsaturated fat or polyunsaturated fat, such as nuts and seeds and decreasing the intake of carbohydrate and saturated fat, could help to reduce the risk of developing type 2 diabetes.

Replacing carbohydrate and saturated fats with more unsaturated fats could help to lower the risk of diabetes according to new research.

The new study, out of Tufts University in the U.S. state of Massachusetts and the University of Cambridge in the UK, looked at data from 102 randomized controlled trials involving a total of 4,660 adult participants.

The trials provided participants with meals that varied in the types and amounts of fat (saturated, monounsaturated and polyunsaturated) and carbohydrate.

The team then looked at the effects of these various diets on key biological markers of glucose and insulin control, including blood sugar, blood insulin, insulin resistance and sensitivity, and the ability to produce insulin in response to blood sugar, which are linked to an increased risk of developing type 2 diabetes.

The researchers found that eating more foods rich in monounsaturated fat or polyunsaturated fat, such as walnuts, sunflower seeds, soybeans, flaxseed, fish, and other vegetable oils and spreads, in place of saturated fats such as animal fats and carbohydrates such as refined grains, starches, sugars, had a beneficial effect on key markers of blood glucose control.

Patients showed lower blood sugar levels and improved insulin resistance and secretion, and for each five per cent of dietary energy switched from carbohydrates or saturated fats to mono- or polyunsaturated fats, there was an approximately 0.1 per cent reduction in HbA1c, a blood marker of long-term glucose control. Based on prior research, each 0.1 per cent reduction in HbA1c is estimated to reduce the incidence of type 2 diabetes by 22 per cent, and cardiovascular diseases by 6.8 per cent.

Commenting on the significance of the results, senior author Dariush Mozaffarian said, "Until now, our understanding of how dietary fats and carbohydrate influence glucose, insulin, and related risk factors has been based on individual studies with inconsistent findings. By combining results from more than 100 trials, we provide the strongest evidence to-date on how major nutrients alter these risks."

With global rates of insulin resistance and type 2 diabetes on the rise the authors now hope that the findings will help inform not only health practitioners but also the public on how dietary fats and carbohydrates affect metabolic health, with Mozaffarian concluding that, "This is a positive message for the public. Don't fear healthy fats."

The findings can be found online in the journal PLOS Medicine.