Very low-carb diet may improve glycemic control in type 1 diabetes with few adverse events, study finds

Researchers conducted an online survey of an international social media group of people with type 1 diabetes who follow a very low-carb diet (up to 30 g/d derived from fibrous vegetables and nuts).


Adhering to a very low-carbohydrate diet may help patients with type 1 diabetes improve their HbA1c levels, a recent study found.

Researchers conducted an online survey of an international social media group of people with type 1 diabetes who follow a very low-carb diet (up to 30 g/d derived from fibrous vegetables and nuts). They assessed current HbA1c, self-reported change in HbA1c since beginning the very low-carb diet, total daily insulin dose, and adverse events. When possible, they confirmed participants' reports with data from their clinicians and/or medical records. Results were published online on May 7 by Pediatrics.

Group members who were age 18 years or older were eligible if they or a child in their care met three self-reported criteria: having type 1 diabetes, receiving insulin, and consuming a carbohydrate-restricted diet for at least three months. Of the 316 survey respondents (58% of respondents were adult patients, and 42% were parents of pediatric patients), 273 respondents (86%) had at least suggestive evidence of type 1 diabetes, including age and weight at diagnosis, pancreatic autoimmunity, insulin requirement, and clinical presentation. The mean age at diabetes diagnosis was 16 years, the mean diabetes duration was 11 years, and the mean time following a very low-carb diet was 2.2 years. Of the respondents, 223 reported their actual carbohydrate consumption and these participants averaged daily carb intake of 36 g for at least three months.

Among 300 respondents, the mean self-reported current HbA1c level was 5.67% ± 0.66%. Among the 127 participants who provided both pre- and post-diet HbA1c values, the average change was −1.45% ± 1.04% (P<0.001). The mean daily insulin dose was 0.40 ± 0.19 U/kg. Participant-reported adverse events were minimal. Of 300 participants, seven (2%) were hospitalized in the prior 12 months, including four for ketoacidosis and two for hypoglycemia. Overall, 69% of participants reported symptomatic hypoglycemia within the past month, with 2% reporting hypoglycemia with seizure or coma and 4% requiring glucagon. Participants had low triglyceride levels, high HDL cholesterol levels, and high LDL cholesterol levels.

The study authors noted limitations, such as how they could not prove that all participants had type 1 diabetes, how the generalizability of the findings is unknown because participants may represent a subgroup of highly motivated people, and how detailed information about the dietary approach was not collected.

The results, if sustained, suggest that a very low-carb diet may be a novel method for improving glycemic control in patients with type 1 diabetes, according to an accompanying editorial. However, the study's limitations mean that a future randomized controlled trial is warranted, the editorialists said.

Even if the therapy is deemed effective, uptake among patients and clinicians may be another obstacle, they noted. In the study, about 27% of participants reported not discussing their very low-carb diets with their clinicians, and only about 49% reported that their clinicians were supportive.

“This finding reveals the need for improved communication and shared decision-making between the patient, caregiver, and provider regarding the overall management of [type 1 diabetes] and the need for greater dialogue within the [type 1 diabetes] community regarding dietary standards of care,” they wrote.