Short-term Effects of Low Carbohydrate Diet on Glycaemic Parameters and Cardiovascular Risk Markers in Patients with Type 1 Diabetes - A Randomised Open-label Cross-over Trial

The objective was to compare effects of high carbohydrate diet (HCD) versus low carbohydrate diet (LCD) on glycaemic parameters and cardiovascular risk markers in patients with type 1 diabetes. Ten patients (4 women, insulin pump-treated, median±SD age: 48 ± 10 years, HbA1c: 53 ± 6 mmol/mol (7.0 ± 0.6%)) followed one week of isocaloric HCD (≥250 g/day) and one week of isocaloric LCD (≤50 g/day) in random order. After each week, we downloaded pump and sensor data and collected fasting blood and urine samples. Diet compliance was high (225 ± 30 vs 47 ± 10 g carbohydrates/day, p < 0.0001). Mean sensor glucose levels were similar between diets (7.3 ± 1.1 vs 7.4 ± 0.6 mmol/l, p = 0.99). LCD resulted in more time in 3.9-10.0 mmol/l (83 ± 9 vs 72 ± 11%, p = 0.02), less time ≤3.9 mmol/l (3.3 ± 2.8 vs 8.0 ± 6.3%, p = 0.03), and less glucose variability (SD 1.9 ± 0.4 vs 2.6 ± 0.4 mmol/l, p = 0.02) than HCD. Cardiovascular markers were unaffected, while fasting glucagon, ketone and free fatty acid levels were higher at end of the LCD-week than the HCD-week. In conclusion, LCD resulted in more time in euglycaemia, less time in hypoglycaemia and less glucose variability than HCD without altering mean glucose levels.