Low-Carb Diet May Be Best in Type 2

December 1, 2007
By Fran Lowry 

NEW ORLEANS —A low-carbohydrate diet, which used to be the only treatment for diabetes before the advent of insulin, may turn out to be the preferred diet for overweight individuals with type 2 diabetes, researchers said at the annual meeting of NAASO, the Obesity Society.

In a poster, preliminary results from a randomized trial of two dietary regimens for weight loss—a low-carbohydrate, ketogenic diet alone, or a low-fat, energy-restricted diet plus drug therapy with orlistat (Xenical) —showed that the low-carb regimen produced more favorable changes in hemoglobin A1c (HbA1c) in a subset of diabetic patients. The diet also reduced or eliminated their need for insulin or other diabetes medications, more so than the orlistat diet, said Jennifer R. McDuffie, Ph.D., of Duke University, Durham, N.C.

In the 6 months that the trial has been ongoing, weight loss with both regimens has been similar (10–12 kg) and so has the reduction in waist circumference. “Because the weight loss has been the same in both groups, we think that the low-carbohydrate ketogenic diet may be exerting its good effects on HbA1c because of its low carbohydrate content,” Dr. McDuffie said in an interview.

The study, which is planned to last 48 weeks, includes 146 outpatients from the Durham Veterans Affairs Medical Center. All have a body mass index 27 kg/m

After 24 weeks, the mean HbA1c among the 22 type 2 diabetes patients in the low- carb arm dropped from 7.5% to 6.8%, a significant reduction. The HbA1c in the 24 type 2 diabetes patients in the orlistat arm went from 7.6 to 7.4, and did not fall significantly from baseline, Dr. McDuffie said.

The need for metformin was decreased or eliminated in 15 (68%) of the 22 patients on the low-carbohydrate ketogenic diet, compared with 7 (29%) of the 24 patients on the orlistat low-fat diet. The low-carbohydrate ketogenic diet also had a favorable effect on HDL-cholesterol levels in all patients, regardless of their type 2 diabetes status. The mean increase in HDL cholesterol was 4 mg/dL in the low-carb group, compared with 0.4 mg/dL in the orlistat group.

Dr. McDuffie stressed that these results are preliminary, and that further analysis of factors such as adherence, physical activity, and adverse events is needed.