Low-carb diets: A good way to manage type 1 diabetes?

If you, or your child, live with type 1 diabetes (T1D), you know that blood sugar levels can vary significantly after meals. Mostly, it’s the amount of carbs you eat that affects your blood sugar. Still, many other factors can cause low blood sugar (hypoglycemia) or high blood sugar (hyperglycemia) after a meal.

Since it’s hard to manage meals and blood sugar levels, lots of people with T1D eat a low-carb diet.

But how does a low-carb diet affect your HbA1c (your average blood glucose over three months)? What are the risks of hypoglycemia? And is your cardiovascular health affected and, if so, how? Due to the limited number of T1D participants in research studies examining how a low-carb diet can influence these health factors, there are currently no clear answers to these questions.

Researchers from the BETTER project wanted to learn more and decided to analyze dietary intake data reported in the BETTER registry between 2019 and 2021 by 285 adults living with T1D or LADA diabetes in Quebec*.

What is a low-carb diet?

There is no official definition, but research suggests that a low-carb diet is one where you eat less than 150g of carbohydrates a day. That’s 30% of your total daily energy intake.

Health Canada and Diabetes Canada suggest that a person’s diet includes carbohydrates, like bread, pasta, rice, and fruits, for about 45% to 60% of their total daily energy needs. For someone eating 2,000 calories a day, that means about 225 to 300 grams of carbohydrates.

Reducing carbohydrate intake would result in improved HbA1c levels

After studying data from the BETTER registry (including information from food diaries, waist measurements, hypoglycemia and HbA1c results, and cholesterol levels), the research team concluded that eating less carbohydrates (31 % of total daily energy intake or about 167g/day on average — which one-quarter of the study participants followed) is linked to a higher chance of reaching the target HbA1c of 7.0% or less. This value is recommended for most people living with T1D to reduce the risk of various diabetes-related complications (e.g., eye and kidney damage). To reach that target, blood sugar levels should stay within the recommended target range (between 3.9 and 10 mmol/L) most of the time.

Remember that blood sugar management remains a significant challenge for most people living with T1D. According to our latest data, about 70% of BETTER registry participants did not reach the recommended HbA1c of 7.0% or less on their last blood work.

No short-term effects on hypoglycemia or cardiovascular risk factors

Although a reduced carbohydrate diet could, in theory, lead to an increased risk of hypoglycemia (since carbohydrates raise blood sugar), researchers did not observe more such episodes in the 285 BETTER registry participants included in their analysis.

Similarly, although some of the carbohydrates removed from the diet were replaced with fats, blood data from the same people did not show higher levels of bad cholesterol (LDL), a marker of cardiovascular disease risk. However, this last observation should be taken with a grain of salt and needs to be validated by other research projects, as several study T1D participants were on medication to control their cholesterol (statins).

What can we take away from this BETTER registry analysis?

The results suggest that low-carb diets are associated with better blood sugar management in people living with T1D or LADA, without necessarily increasing the risk of severe hypoglycemia or factors that may promote cardiovascular diseases, at least in the short term.

However, further studies are needed to confirm these findings and assess the long-term effects of a low-carb diet on cardiovascular health and nutrient intake.

*Participant characteristics: 63% are women, the average age is 48 years, they have had diabetes for an average of 26 years, 40% use a pump, over 72% have a continuous glucose monitor, 94% are of Caucasian descent, and 9.5% live with LADA diabetes.

Reference :

• Nguyen, É. et al. (2024). Association between low-carbohydrate-diet score, glycemia and cardiovascular risk factors in adults with type 1 diabetes. Nutrition, Metabolism and Cardiovascular Diseases. https://www.sciencedirect.com/science/article/pii/S0939475324001649?ref=pdf_download&fr=RR-2&rr=884c5483fe137133