Unlike type 2 diabetes, which can be caused by lifestyle factors such as poor diet and lack of exercise, type 1 diabetes is most likely caused by an autoimmune reaction that destroys cells in the pancreas that make insulin. It affects only about 10 percent of people with diabetes and often manifests in childhood. Symptoms include frequent urination (especially at night), blurred vision, tingling in the extremities, and fatigue.
While there is no cure, type 1 diabetes can be managed through a combination of insulin shots and lifestyle changes aimed at keeping blood sugar levels within target ranges as much as possible. To that end, researchers at the University of Gothenburg in Sweden set out to test the effects of a low-carb diet on adults with type 1 diabetes. Their results were published in December in The Lancet Regional Health—Europe.
The Study
The Swedish team recruited 50 participants who all had type 1 diabetes with elevated mean glucose, long-term blood sugar, and injection therapy with insulin or an insulin pump. Subjects had an average age of 48; half of them were women and half were men.
Participants were randomly assigned to eat either a traditional diet (50% of calories from carbohydrates) or a moderate low-carb diet (30% of calories from carbohydrates). Both diets were healthy in terms of fat and carbohydrate quality. They included vegetables, fiber-rich carbohydrate sources, unsaturated fats, nuts, seeds, and legumes.
The researchers performed 24-hour monitoring of all participants via continuous glucose monitoring (CGM) throughout the 16-week study period. Blood glucose levels were recorded at least every 15 minutes and were followed up by a dietitian and diabetes nurse.
At the conclusion of the study, the researchers found that participants on the low-carb diet spent an average of 68 minutes longer per day in the blood sugar target range than participants on the traditional diet. The low-carb group also saw their time with elevated blood sugar reduced by 85 minutes per day.
Additionally, the researchers saw no evidence of adverse effects from the low-carb diet. Cholesterol and blood pressure levels remained similar for people on both diets, and participants also felt a bit more satisfied with the moderate low-carbohydrate diet. There had been some concern that ketone levels might become elevated when carbohydrates were reduced in type 1 diabetes, but the participants’ ketones all remained within reasonable levels.
Conclusions
The researchers emphasize that, for safety reasons, major changes in carbohydrate intake in type 1 diabetes should always be made in consultation with the healthcare provider. Individuals should not make these dietary changes on their own, especially not for children with type 1 diabetes, as the current study followed only adults.
That said, the results of the study are promising. “The study shows that a moderate low-carbohydrate diet lowers the average blood sugar level and that more patients can keep their blood sugar within the target range, which is considered beneficial in reducing the risk of organ damage for people with type 1 diabetes,” said Sofia Sterner Isaksson, the study’s first author. “However, it is important that the diet is healthy with a particular focus on fat and carbohydrate quality, and that the amount of carbohydrates is not too low so it can be considered safe.”
