By Megan Rauscher
NEW YORK (Reuters Health) - Restricted-carbohydrate diets seem to improve blood sugar control and reduce harmful triglyceride levels in adults with type 2 diabetes, but it is unclear whether these diets aid in weight control or weight loss, new research suggests.
"Many patients with diabetes are looking for ways to lower blood sugar, and they are often confused about which meal plan would be best for them to follow," Dr. Julienne K. Kirk from Wake Forest University School of Medicine, Winston-Salem, North Carolina, noted in an email to Reuters Health.
"Even health professionals -- aware that carbohydrate foods have the largest impact on blood sugar -- are sometimes uncertain what type of diet to suggest to their patients," she added.
Kirk and colleagues pooled data from 13 studies that evaluated restricted-carbohydrate diets in type 2 diabetic patients. "We included studies with a wide range of dietary carbohydrate content in this meta-analysis, from 4 percent to 45 percent of calories, to try to determine if there is a moderately restricted carbohydrate amount that would impact diabetes-related outcomes," they point out in the Journal of the American Dietetic Association.
The results showed that even moderate decreases in carbohydrates can be beneficial in treating type 2 diabetes, not only leading to improved blood sugar control but also to positive changes in lipid levels.
For example, a decrease in dietary carbohydrates from 65 percent to 35 percent could be expected to lead to about a 23 percent fall in triglycerides, the investigators report.
However, the overall effect of restricted-carbohydrate diets on body weight was equivocal.
Kirk noted that there is currently insufficient evidence to recommend low or very low carbohydrate diets (that is, less than 130 grams per day) in patients with diabetes "since long-term effects have not been fully investigated."
As a point of reference, 130 grams of carbohydrates equals 43 percent of calories in a 1,200-calorie diet, 30 percent of calories in a 1,700-calorie diet, and 24 percent of calories in a 2,200-calorie diet.
"While restriction of carbohydrate content is a necessary part of most meal plans, it must be achieved without sacrificing essential nutrients," Kirk said. "The key, as in many aspects of diet and health, may lie in moderation."
SOURCE: Journal of the American Dietetic Association, January 2008.