The glycaemic benefits of a very-low-carbohydrate ketogenic diet in adults with Type 1 diabetes mellitus may be opposed by increased hypoglycaemia risk and dyslipidaemia.

AIMS

To investigate whether very-low-carbohydrate high-fat diets, typical of ketogenic diets, can improve glycaemic control without causing any ill health effects in adults with Type 1 diabetes.

METHODS

In this observational study, 11 adults with Type 1 diabetes (seven men, four women, mean ± sd age 36.1± 6.8 years, mean ± sd duration of diabetes 12.8 ± 10.3 years), who followed a ketogenic diet (< 55 g carbohydrate per day) for a mean ± sd of 2.6 ± 3.3 years (β-hydroxybutyrate 1.6 ± 1.3 mmol/l), underwent sampling and analysis of fasting blood, and were fitted with a blinded continuous glucose monitor for 7 days to measure glycaemic variability.

RESULTS

The mean ± sd HbA levels were 35±4 mmol/mol (5.3±0.4%), and participants spent 74±20 and 3±8% of their time in the euglycaemic (4-8 mmol/l) and hyperglycaemic (>10 mmol/l) ranges, respectively, with little daily glycaemic variability (sd 1.5±0.7 mmol/l; coefficient of variation 26±8%). Blood glucose levels were <3.0 mmol/l for 3.6% of the time, and participants experienced a median (range) of 0.9 (0.0-2.0) daily episodes of hypoglycaemia. Total cholesterol, LDL cholesterol, total cholesterol/HDL cholesterol ratio, and triglycerides were above the recommended range in 82%, 82%, 64% and 27% of participants, respectively; however, HDL cholesterol levels were within the recommended range for all participants. Participants displayed no or little evidence of hepatic or renal dysfunction.

CONCLUSION

This study provides the first evidence that, ketogenic diets in adults with Type 1 diabetes are associated with excellent HbA levels and little glycaemic variability, but may also be associated with dyslipidaemia and a high number of hypoglycaemic episodes.