In contrast, no such improvements were seen among people who swapped their normal carbs for a daily whole-wheat muffin.
For the study, published in Diabetes Care online, Dr Cyril W.C. Kendall of the University of Toronto in Canada and colleagues randomly assigned 117 adults with type 2 diabetes to one of three groups, one group was given unsalted mixed nuts and told to eat about a half-cup instead of some of their usual carbs, a second group replaced their normal carbs with healthy whole-wheat muffins with no added sugar.
The third group went on a half-nut/ half-muffin regimen.
Study put to test
The full-nut group ate, on average, about two half cups of nuts per day, which totalled roughly 1995kJ. After three months, the researchers found, the full-nut group showed a 0.2% dip in their average haemoglobin A1C level.
The change was small, and just shy, Dr Kendall said, of what's considered a clinically significant improvement in blood sugar control.
But, he added, people in the study were already on diabetes medication and typically had good blood glucose control. "So we're seeing a benefit over and above what they were achieving with medication," Dr Kendall said.
As for cholesterol, the nut group's average LDL cholesterol level declined from about 97 to 89 mg/dL.
No similar improvements were seen in the other two groups. It's not clear why the full-nut group showed better blood glucose and LDL levels. Dr Kendall said he suspects it is largely because of the monounsaturated fats in nuts.
"But, they also have protein, there's a little fibre, and some polyphenols," he added.
The current study was partially funded by the International Tree Nut Council Nutrition Research & Education Foundation and the Peanut Institute, both industry groups.
(Reuters Health, July 2011)