Risk of pathological ketoacidosis with very low carbohydrate diet in type 1 diabetes patients lower than feared

The researchers found an association of carbohydrate-restricted diets, in particular, VLCDs (very low-carbohydrate diets) with a higher beta-hydroxybutyrate (BOHB) level. In the study, the degrees of ketosis were observed to be much lower than expected and significantly less than the level typically associated with diabetic ketoacidosis. Although safety needs to be investigated further in large-scale randomized trials, the researchers wrote.

There has been an increasing popularity of dietary carbohydrate restriction, and is a controversial, approach selected by patients with type 1 diabetes. The main fear of following these diets (low or very low carbohydrate diets) is that they may raise the risk of diabetic ketoacidosis. However, there is limited data about the ketoacidosis risk and the level of physiological nutritional ketosis in people following these diets.

To fill this knowledge gap, Fredrik Karpe, University of Oxford, Oxford, UK, and colleagues aimed to define the level of ketosis in those with type 1 diabetes following carbohydrate-restricted diets in a real-world observational study.

For this purpose, the researchers enrolled patients with type 1 diabetes from local clinics who had self-selected dietary carbohydrate restriction and were compared to those following an unrestricted regular carbohydrate control diet (RCCD). Participants completed a 3-day diary documenting ketones, food intake, and blood/interstitial glucose concentrations.

The researchers revealed the following findings:

· Participants were divided into three groups according to mean carbohydrate intake: VLCD (<50 g carbohydrates/day) n = 6, LCD (50–130 g carbohydrates/day) n = 6, and RCCD (>130 g carbohydrates/day) n = 3.

· Mean beta-hydroxybutyrate (BOHB) concentrations were 1.2 mmol/l, 0.3 mmol/l and 0.1 mmol/l in the VLCD, LCD and RCCD groups, respectively.

· Post hoc Dunn test demonstrated this reached statistical significance between the VLCD and RCCD groups.

The study showed that carbohydrate-restricted diets, VLCDs in particular, are associated with a higher capillary concentration of BOHB versus unrestricted carbohydrate diets. However, despite severe carbohydrate restriction, the nutritional ketosis degree seen is much lower than expected, with a range of 0.3–1.15 mmol/L in the carbohydrate-restricted groups.

"There is a need for large-scale randomised trials to further evaluate the safety and efficacy of carbohydrate restriction as a dietary strategy in type 1 diabetes," the researchers wrote.

"Given that, only 8.1% of patients with T1D achieved the recommended HbA1c of <48 mmol/L (<6.5%) in 2019/2020, should the safety of LCD/VLCDs be established, this may open an additional therapeutic option for individuals with type 1 diabetes in pursuit of glycaemic targets," they concluded.

Reference:

Ozoran, H., Matheou, M., Dyson, P., Karpe, F., & Tan, G. D. Type 1 diabetes and low carbohydrate diets—Defining the degree of nutritional ketosis. Diabetic Medicine, e15178. https://doi.org/10.1111/dme.15178