Glycaemic stability of a cyclist with Type 1 diabetes: 4011 km in 20 days on a ketogenic diet.
Level 4 - case-series / case-control
Single-patient case report
PubMed 31197870 · doi:10.1111/dme.14049
What was done
Case report of a 37-year-old male with Type 1 diabetes who completed a 4,011 km cycle across Australia over 20 consecutive days while consuming a very-low-carbohydrate ketogenic diet. Glycemic metrics were tracked using continuous glucose monitoring (CGM).
What was found
CGM data capture was 98.4% across the 20 days. Average interstitial glucose was 6.1 mmol/l with a standard deviation of 2.1 mmol/l, and the individual spent 80.4% of the time in the target range of 3.9–10.0 mmol/l. Glucose levels fell below 3.0 mmol/l for 2.1% of the duration, resulting in a single symptomatic hypoglycemia episode requiring carbohydrate intake and brief exercise cessation.
Why it matters
Provides proof-of-concept that extreme endurance exercise on a very-low-carbohydrate ketogenic diet is achievable with stable blood glucose in an individual with Type 1 diabetes.
Limits
As a single-subject case report (n = 1), findings cannot be generalized to broader populations of athletes with Type 1 diabetes. There was no control or high-carbohydrate comparator condition, and exact macronutrient intake or performance metrics were not detailed in the abstract.
Cited by
- context Adherence to a ketogenic diet results in a continuous glucose monitor trace that is completely flat, absent major exercise or severe stress.