Study suggests benefits of very low carbohydrate intake in type 1 diabetes
medwireNews: A study of type 1 diabetes patients voluntarily following a very-low-carbohydrate diet (VLCD) suggests that the approach could help to achieve excellent control of blood glucose levels.
As reported in Pediatrics, David Ludwig (Boston Children’s Hospital, Massachusetts, USA) and co-researchers recruited 316 patients with type 1 diabetes who were members of a closed Facebook group for people following a very-low-carbohydrate diet of up to 30 g (depending on weight) from fibrous vegetables and nuts.
This makes it one of the largest studies of very-low-carbohydrate diets in type 1 diabetes patients. A recent systematic review identified just nine studies, including two randomized controlled trials, the largest of which had 48 patients. The studies were so varied that the reviewers were unable to calculate an overall effect size for following a low-carbohydrate diet.
In a linked commentary, Carly Runge and Joyce Lee, from University of Michigan in Ann Arbor, USA, describe the current study as “an important contribution to the literature,” but caution that all participants were highly motivated and had well-controlled blood sugar even before they started a VLCD, with an average glycated hemoglobin (HbA1c) level of 7.15%.
“Furthermore, the VLCD may have been accompanied by changes in other aspects of diabetes management, such as maintaining stricter adherence to the insulin regimen, that could not be controlled for with the study design,” they write, stressing the need for a randomized trial.
However, participants’ average HbA1c at the time of recruitment was 5.64% among the 185 adult participants and 5.71% among the 131 children, which the commentators describe as “an exquisite level of control.” At this point, all participants had been following a VLCD for at least 3 months, with an average of 2.2 years.
Adverse event rates were low and did not increase after patients started the VLCD. Participants reported 14 hospitalizations over the preceding 12 months, with four of these being for diabetic ketoacidosis. Although 69% of participants reported symptomatic hypoglycemia, most of these (55%) had between one and five episodes per month, and just 4% required glucagon and 2% had hypoglycemic seizure or coma.
Although stressing that adverse events were self-reported and therefore not guaranteed to be accurate, Runge and Lee highlight that this is the first study large enough to assess the association of a VLCD with adverse events.
Among the children, there was no indication that the diet impacted growth, with height standard deviation scores not associated with carbohydrate intake goal or diet duration, although the commentators caution that the researchers could not assess pubertal development, “which limits an accurate interpretation of growth patterns.”
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