Low carbohydrate diets and type 1 diabetes

This summer, Diabetes Canada published a position statement on low and very low carbohydrate diets in people living with type 1 and type 2 diabetes. Here, we review the evidence and recommendations regarding these diets for adults with type 1 diabetes (T1D).

Carbohydrates are one of the three main macronutrients, along with proteins and fats. These three molecules are called macronutrients because they provide us with energy. Carbohydrates can be found in foods like grains, legumes, fruit, dairy, starchy vegetables, and sugary processed foods. In most people’s diets, carbohydrates are the main source of energy. In fact, both Health Canada and Diabetes Canada recommend that 45-60% of total energy in your diet come from carbohydrates. 

On the other hand, low carbohydrate (50-130g of carbs/day) and very low carbohydrate diets (<50g of carbs/day, also called ketogenic diets) have emerged as a popular alternative in recent years. These diets require restriction of carbs and a higher intake of protein and fat from foods like meat, poultry, fish, eggs, and nuts. Because of their popularity, it is important to address the implications of these diets in the management of T1D. 

Low carbohydrate vs. ketogenic diets

A ketogenic diet is one that makes your body go into ketosis. In ketosis, the body does not have enough glucose to feed the brain, so it uses molecules called ketone bodies instead, which are made from fats. In order to go into ketosis, you need to eat less than 50g of carbs per day (very low carbohydrate diet). A low carbohydrate diet is not ketogenic because it contains more than 50g of carbs per day.

The Diabetes Canada Position Statement

In their Position Statement, Diabetes Canada reviewed available research regarding low and very low carbohydrate diets in T1D (as well as type 2 diabetes). They found that the few studies available show possible benefits of these diets in reducing HbA1c and glycemic variability. However, there is still a lack of research in this area, and available studies have several limitations, including being short-term. This means it is hard to make general long-term recommendations based on these results. The Position Statement also found that low and very low carbohydrate diets are difficult for most people to maintain long-term. 

Lastly, it highlighted several safety considerations that are important to keep in mind when on these types of diets. These include lower insulin needs, an increased risk of hypoglycemia, difficulty in detecting hypoglycemia, an elevated risk of diabetic ketoacidosis (DKA), and nutrient deficiencies.

Conclusions and recommendations

In conclusion, although some studies show that low and very low carbohydrate diets are effective at reducing HbA1c and glycemic variability, there is still a lot we don’t know. In their position statement, Diabetes Canada does not make a specific recommendation for or against these diets for people with T1D. They do, however, make some general recommendations for those who choose to follow these diets:

1. People living with T1D should be supported to choose healthy dietary patterns consistent with the individual’s values, goals and preferences.
2. Healthy (as per Canada’s Food Guide) low or very low carbohydrate diets can be considered as one healthy eating pattern for individuals living with T1D. You should consult your healthcare provider to reduce the likelihood of adverse effects.
3. If you choose to begin a low carbohydrate diet, you should seek support from a dietitian who can help create an appropriate plan.

References:

• Barnes, T.  (2020). Diabetes Canada Position Statement on Low Carbohydrate Diets for Adults with Diabetes: A Rapid Review. Canadian Journal of Diabetes 44(4): 295-299.
• Paoli, A., Rubini, A., Volek, J.S., & Grimaldi, K.A. (2013). Beyond weight loss: a review of the therapeutic uses of very-low-carbohydrate (ketogenic) diets. European Journal of Clinical Nutrition, 67: 789–796.