Nobody ever compared whether a low-carb or a low-glycemic diet works better to control our blood glucose levels. Until now.
Both diets improved A1C levels and helped participants in a 24-week study to lose weight. But the low-carb group did a lot better.
Five doctors at the Duke University Medical Center in Durham, North Carolina, just reported their results in the journal Nutrition & Metabolism. Led by Eric Westman, M.D., the study, "Effect of a low-carbohydrate, ketogenic diet versus a low-glycemic index diet on glycemic control in type 2 diabetes mellitus," appeared on December 19.
The low-carb group followed a really low-carb diet -- less than 20 grams of carbohydrate daily -- but weren't told to restrict their caloric intake. The low-glycemic group not only followed a low-GI diet but also reduced their caloric intake. Their diet gave them 500 calories per day less than they needed to maintain their weight.
Everyone in both groups had both type 2 diabetes and obesity. A total of 49 participants, who the researchers randomized to one group or the other, completed the study.
The researchers looked primarily at glycemic control as measured by A1C levels. Average A1C levels of the low-carb group went down 1.5 percent, for example from 8.5 to 7.0. Average A1C levels of the low-glycemic group went down too, but just 0.5 percent.
The low-carb group lost an average of 24 pounds. The low-glycemic group averaged a loss of 15 pounds.
HDL cholesterol -- the so-called "good cholesterol" -- also went up among the low-carb group, averaging an improvement of 5.6 mg/dl. But the low-glycemic group saw no change.
One more measure shows how powerful a low-carb diet can be: 95 percent of those in the low-carb group were able to reduce or eliminate their diabetes medication versus 62 percent for those in the low-glycemic group.
The researchers also provided some detail about the low-carb diet. Allowed foods were unlimited amounts of animal foods -- including meat, poultry, fish, and shellfish -- and eggs. Their limit for hard cheese was 4 ounces per day and for fresh cheese, like cottage or ricotta, 2 ounces per day. They could eat 2 cupfuls of salad vegetables and 1 cupful of non-starchy vegetables per day.
One caveat: the Robert C. Atkins Foundation provided funding for the study. The late Dr. Atkins deserves the credit for initially popularizing the low-carb diet.
The results of the study may surprise the "so-called diabetes experts." But they probably didn't surprise the Atkins people and certainly didn't surprise me one bit.
I've lived these diets. For most of my diabetes experience I followed and recommended a low-glycemic diet. I know that eating high-glycemic foods like potatoes or anything made from wheat flour wreaks havoc with my blood glucose levels. But I also know from my own experience of more than a year on a low-carb diet that nothing else offers comparable control.