Very-low-carb diet can safely curb blood sugar in type 1 diabetes, study suggests
David Ludwig, MD, PhD, an endocrinologist at Boston Children’s Hospital, has written popular books espousing a low-glycemic, low-carbohydrate diet for weight control. He has argued that high-glycemic diets are contributing to the epidemic of type 2 diabetes. But he hadn’t given much thought to carbohydrate restriction for type 1 diabetes until 2016.
At a conference, Ludwig met a surgeon with type 1 diabetes who maintains normal hemoglobin A1c levels (indicating high blood sugar control) on a very-low-carbohydrate diet. This surprised and impressed him: he had never seen any patient with type 1 diabetes able to completely normalize their hemoglobin A1cs. Moreover, most diabetes experts discourage very-low-carb diets, believing they pose a risk for hypoglycemia, or a dangerous drop in blood sugar.
The surgeon told Ludwig about TypeOneGrit, a Facebook community of children and adults with type 1 diabetes who follow a very-low-carbohydrate diet espoused by the book Dr. Bernstein’s Diabetes Solution. Ludwig decided to conduct an observational study of this community, together with Boston Children’s endocrinologist Belinda Lennerz, MD, PhD. Book author Richard Bernstein, MD, is a co-author.
‘Exceptional’ blood sugar control
Ludwig and Lennerz analyzed survey responses from 316 community members. For 138 members, they were able to corroborate survey responses with health care providers or through a review of medical records.
It’s time to refocus on the medicinal power of diet,” says Ludwig. As reported today in Pediatrics, self-reported hemoglobin A1c values averaged in the normal range, at 5.67 percent. (The target is below 7 percent; prevailing levels average 8.2 percent.) Some survey respondents even had values in the 4 percent range, Ludwig says. Average daily carb intake was 36 grams, or about 5 percent of total calories. For comparison, the American Diabetes Association recommends about 45 percent of calories come from carbohydrates.
Participants also reported needing lower-than-average doses of insulin (mean, 0.40 U/kg/day). “With fewer carbohydrates (especially fast-digesting grain products, potatoes and sugary foods), blood sugar rises and falls more gently after eating, making for an easier target to hit accurately with insulin,” writes Ludwig in his blog.
Respondents for whom data were available had favorable measures of insulin sensitivity and cardiometabolic health, such as low triglyceride levels and high HDL cholesterol levels. Hospitalization rates for diabetes complications were actually lower than those generally reported for type 1 diabetes populations — just 1 percent for hypoglycemia and 2 percent for diabetic ketoacidosis.
Type 1 diabetes: Back to the future?
Severe carbohydrate restriction is actually a very old approach in type 1 diabetes. Before the discovery of insulin, it extended children’s lives, sometimes for years. Once insulin was introduced, carb restriction fell out of practice. Notably, about a quarter of Ludwig’s survey respondents said they hadn’t discussed the very-low-carb diet with diabetes care providers, not wanting to spark a disagreement. Some parents even cited concerns about being accused of child abuse.
Since this study wasn’t controlled, Ludwig and Lennerz call for randomized clinical trials to rigorously test very-low-carb diets in type 1 diabetes. They also suggest more research on less-restrictive low-carb diets and how best to dose insulin with these diets and physical activity. For now, they urge that dietary changes be made only with the supervision of a diabetes care provider.
“These limitations notwithstanding, our findings raise the possibility that much better diabetes control than currently thought possible might be achievable — with the hope of preventing feared long-term complications,” writes Ludwig. “After many decades focused almost entirely on new (and expensive) drugs and technology, it’s time to refocus on the medicinal power of diet.”
The study was supported by the NIH National Institute of Diabetes and Digestive and Kidney Diseases. Lennerz and Ludwig are both affiliated with the Division of Endocrinology and New Balance Foundation Obesity Prevention Center at Boston Children’s Hospital and Harvard Medical School.