Very low carbohydrate diets show potential benefits in children with type 1 diabetes

Very low carbohydrate (VLC) diets may be associated with health benefits in children with type 1 diabetes (T1D) and were not associated with acute diabetes complications, new research being presented at the annual meeting of the European Association for the Study of Diabetes (EASD) in Milan, Italy (Sept 28 – Oct 2) has found.

Growing numbers of parents are using low- and very low carbohydrate diets to improve glycaemic control (manage blood sugar levels) in their children when they have T1D.

Professor Christian Denzer, of the Department of Paediatrics and Adolescent Medicine, Division of Paediatric Endocrinology and Diabetes, University Medical Center Ulm, Ulm, Germany, who led the research together with co-author Dr Belinda Lennerz of Boston Children's Hospital, Harvard Medical School, Boston, USA, explains: "These diets are becoming more popular among people with diabetes because patients themselves notice encouraging results, including much better blood sugar control and lower insulin needs.

"Theoretical safety issues include nutrient deficiencies, high cholesterol, low blood sugar, and ketoacidosis – a life-threatening complication of diabetes. In children, there is the additional concern about potentially affecting growth.

"Remarkable benefits on blood sugar and insulin needs have been corroborated in several observational and small interventional studies, while no major safety events have been published to date. An observational study led by Dr Belinda Lennerz, involving 316 children and adults, found major glycaemic benefits with mixed effects on cholesterol and no apparent adverse effect on growth or acute diabetes complications.

"However, large, long-term studies are needed to confirm the health benefits and safety of low- and very low carbohydrate diets."

To help address this, Dr Lennerz and Professor Denzer, together with colleagues in Germany, used 25 years of data from a diabetes prospective follow-up registry to examine the relationship between VLC diets, growth and metabolic safety in children aged 1-17.

The study, the largest of its kind, involved 45,569 children (55% male, average age 10.3 years) with T1D whose carbohydrate intake had been recorded at least twice over a period of a year or more.

The children's diets were categorized based on their carbohydrate content (carbohydrate percentage of estimated energy intake): VLC (<10% carbohydrate, 219 children), low carbohydrate (LC, 10-<26% carbohydrate, 4,837 children) and standard/higher-carbohydrate intake (SC, ≥26%, 40,513 children). Average follow-up period was 2.18, 2.40, and 3.67 years, respectively.

Height and weight were tracked (taking into account that the children were still growing), as well as changes in blood sugar control (glycaemic trajectories), insulin use and rates of two severe metabolic complications of diabetes: hypoglycaemia and diabetic ketoacidosis.

The analysis did not flag up any safety concerns in the areas examined. There was no evidence that a VLC diet stunted growth or that VLC diets were associated with severe hypoglycaemia or diabetic ketoacidosis.

The analysis also found that lower carbohydrate intake was associated with some favorable changes, such as improved BMI and glycaemic trajectories.

BMI increased less, and so remained closer to a healthier weight, in the children following VLC and LC diets than those on SC diets.

HbA1c (average blood sugar levels in the past two to three months) and dose of basal insulin (one of two types of insulin typically prescribed for T1D) were lower at the end of the follow-up period and increased less over time in children following VLC and LC diets than in those on SC diets.

Most notably, IDAA1c (blood sugar levels when insulin use is factored in) was also lower at the end of the follow-up period in children following VLC and LC diets.

Dr Lennerz explains: "IDAA1c combines blood sugar levels with the amount of insulin a person needs. A lower IDAA1c therefore means that better blood sugar control was achieved without simply using more insulin, strengthening the finding that VLC and LC diets were associated with both better glycaemic control and lower insulin requirements."

The analyses were adjusted for factors include sex, age, migration background and diabetes duration. However, the authors cannot rule out the possibility that residual confounding by other factors, such as the self-reporting of diet, affected the results.

Dr Lennerz concludes: "Reducing carbohydrate intake improved glycaemic control while reducing insulin needs without negatively impacting growth or increasing the rate of acute diabetes complications.

"These results are very encouraging but remain observational in nature. Additional research is needed to confirm the findings and establish the ideal amount of carbohydrate intake to maximize benefits while avoiding adverse effects and promoting food variety."