Will the Risk of Hypoglycemia Increase on a Ketogenic Diet?
Using or recommending the ketogenic diet as a part of the management of type 1 diabetes is still controversial, which likely stems from the belief that carbohydrates are necessary to avoid hypoglycemia (dangerously low blood glucose). But in fact, a diet rich in carbohydrates increases the need for insulin injections. For those with a daily food intake that includes varying amounts and types of carbohydrates, the insulin dosage may be too high in some cases, resulting in hypoglycemia. On a ketogenic diet, carbohydrate intake is very low and consistent, and therefore the insulin dosage needed is also lower and much more consistent. This reduces the chances of overdosing insulin and causing hypoglycemia. However, it is very important for type 1 diabetics to consult a physician when reducing carbohydrate intake, because insulin dosage will need to be reduced accordingly.
A Proof-of-Concept Study on Carbs and Type 1 Diabetes
To prove the concept that carbohydrates are not essential, a study tested whether it was feasible for eight individuals, two with type 1 diabetes, to exercise over a 5-day period while completely fasted. The participants walked or ran approximately 20 miles per day for 5 consecutive days while only consuming water. All participants completed the study without problems with glycemic control and without any physical injuries. In the participants with type 1 diabetes, blood glucose levels ranged from less than 3mmol/L to 9mmol/L and in participants without type 1 diabetes, blood glucose levels ranged from less than 3mmol/L to 7mmol/L. Results from continuous glucose monitors showed little variability in blood glucose levels in the participants with type 1 diabetes. Ketone levels ranged from 0.3 to 7.5 mmol/L in all participants, and they felt very little hunger. Mood was not negatively affected, but actually enhanced in most participants.
The key points from the study were:
- “People do not need to consume carbohydrates for energy for distances of up to 100 miles.”
- “People who inject insulin for type 1 diabetes management do not need to consume carbohydrates just because they are injecting insulin unless they need to rescue a hypoglycemic episode.”
- “Nutritional ketosis is not a risk factor for diabetic ketoacidosis.”
The authors conclude that the results from this study should reassure clinicians who wants to recommend a ketogenic lifestyle to patients with type 1 diabetes.  In other words, the ketogenic diet is safe for people with type 1 diabetes when followed by their physician.
A large online survey with adults and parents of children with type 1 diabetes (316 participants) evaluated how a ketogenic diet affected glycemic control. They looked at change in HbA1c (a blood test measuring your blood glucose level over the past two to three months) after beginning the ketogenic diet as well as the total daily insulin dose and adverse events. The daily mean intake of carbohydrates was 36g and mean HbA1c was 5.7%. The authors concluded that the participants with type 1 diabetes had exceptional glycemic control and low rates of adverse events.