Endocrine Abstracts

Background: Carbohydrate-restricted diets in type 1 diabetes mellitus (T1DM) are highly controversial. A commonly held concern is that a low carbohydrate diet may more readily result in conversion to diabetic ketoacidosis – one of the most severe complications of poorly managed T1DM. Of note, there is no clear evidence for this phenomenon. We evaluated metabolic profiles in patients with T1DM who had self-selected carbohydrate-restricted diets.

Methods: We analysed data from a three-day evaluation completed by 12 T1DM patients adhering to low- or very-low carbohydrate diets (LCDs or VLCDs respectively) and 3 T1DM patients following regular carbohydrate counting diets (RCCDs). Participants completed a food diary, noted daily insulin usage and measured diurnal blood/interstitial fluid glucose and blood ketones at set daily metabolic intervals.

Results: Participants were divided into three groups according to mean carbohydrate intake: VLCD (<50g carbohydrates/day) n=6, LCD (50–130g carbohydrates/day) n=6, and RCCD (>130g carbohydrates/day) n=3. Data from the three-day metabolic profile evaluation demonstrated significantly raised beta-hydroxybutyrate concentrations (BOHBs) between the VLCD/LCD groups compared with the RCCD group (P=0.004). However, the mean daily BOHB concentrations in the VLCD and LCD groups were lower than expected and ranged from 0.3-1.15mmol/l. Further, VLCD/LCD groups had lower daily mean blood/interstitial fluid glucose concentrations compared to the RCCD group (P=0.021). The reduced carbohydrate intake was also associated with lower insulin doses, a lower variance of glucose and hence a more stable glycaemic profile (P=0.01).

Conclusion: The data obtained suggests that adherence to VLCDs/LCDs in T1DM can facilitate an improved and less variable glycaemic profile. Importantly, these changes occur in a manner that does not mediate concerning supraphysiological increases in BOHB concentrations. The results obtained warrant further research in the form of randomised controlled trials to assess the long-term safety and sustainability of this dietary approach.