Low-Carb Breakfast Key to Lower Glucose Variability in T2D?

Marlene Busko

June 08, 2023

A low-carbohydrate breakfast was better than a control (low-fat) breakfast to decrease glycemic variability throughout the day in type 2 diabetes, in new research.

These findings from a 3-month randomized study in 121 patients in Canada and Australia were published online recently in the American Journal of Clinical Nutrition.

The researchers aimed to determine whether a low-carbohydrate, high-fat breakfast (focused around eggs) compared with a standard, low-fat control breakfast (designed to have no/minimal eggs) would improve blood glucose control in individuals with type 2 diabetes.

"We’ve determined that if the first meal of the day is low-carb and higher in protein and fat we can limit hyperglycemic swings," lead author Barbara Oliveira, PhD, School of Health and Exercise Sciences, University of British Columbia, Kelowna, Canada, said in a press release from the university.

"Having fewer carbs for breakfast not only aligns better with how people with [type 2 diabetes] handle glucose throughout the day," she noted, "but it also has incredible potential for people with [type 2 diabetes] who struggle with their glucose levels in the morning."

"By making a small adjustment to the carb content of a single meal rather than the entire diet," Oliveira added, "we have the potential to increase adherence significantly while still obtaining significant benefits."

The researchers conclude that "this trial provides evidence that advice to consume a low carbohydrate breakfast could be a simple, feasible, and effective approach to manage postprandial hyperglycemia and lower glycemic variability in people living with type 2 diabetes."

Could Breakfast Tweak Improve Glucose Control?

People with type 2 diabetes have higher levels of insulin resistance and greater glucose intolerance in the morning, the researchers write.

And consuming a low-fat, high carbohydrate meal in line with most dietary guidelines appears to incur the highest hyperglycemia spike and leads to higher glycemic variability.

They speculated that eating a low carb breakfast compared with a low-fat breakfast might be an easy way to mitigate this.

They recruited participants from online ads in three provinces in Canada and four states in Australia, and they conducted the study from a site in British Columbia and one in Wollongong, Australia.

The participants were aged 20-79 years and diagnosed with type 2 diabetes. They also had a current A1c <8.5% and no allergies to eggs, and they were able to follow remote, online guidance.

After screening, the participants had a phone or video conference call with a member of the research team who explained the study.

The researchers randomly assigned 75 participants in Canada and 46 participants in Australia 1:1 to the low-carbohydrate intervention or the control intervention.

The participants had a mean age of 64 and 53% were women. They had a mean weight of 93 kg (204 lb), BMI of 32 kg/m2, and A1c of 7.0%. 

Registered dietitians in Canada and Australia each designed 8-10 recipes/menus for low-carb breakfasts and an equal number of recipes/menus for control (low-fat) breakfasts that were specific for those countries.  

Each recipe contains about 450 kcal, and they are available in Supplemental Appendix 1A and 1B, with the article.  

Each low-carbohydrate breakfast contains about 25 g protein, 8 g carbohydrates, and 37 g fat. For example, one breakfast is a three-egg omelet with spinach.

Each control (low-fat) recipe contains about 20 g protein, 56 g carbohydrates, and 15 g fat. For example, one breakfast is a small blueberry muffin and a small plain Greek yogurt.

The participants were advised to select one of these breakfasts every day and follow it exactly (they were also required to upload a photograph of their breakfast every morning). They were not given any guidance or calorie restriction for the other meals of the day.

The participants also filled in 3-day food records and answered a questionnaire about exercise, hunger, and satiety, at the beginning, middle, and end of the intervention.

They provided self-reported height, weight, and waist circumference, and they were given requisitions for blood tests for A1c to be done at a local laboratory, at the beginning and end of the intervention.

The participants also wore a continuous glucose monitor (CGM) during the first and last 14 days of the intervention.

Intervention Improved CGM Measures

There was no significant difference in the primary outcome, change in A1c at the end of 12 weeks, in the two groups. The mean A1c decreased by 0.3% in the intervention group vs 0.1% in the control group (P = .06).

Similarly, in secondary outcomes, weight and BMI each decreased about 1% and waist circumference decreased by about 2.5 cm in each group at 12 weeks (no significant difference). There were also no significant differences in hunger, satiety, or physical activity between the two groups.

However, the 24-hour CGM data showed that mean and maximum glucose, glycemic variability, and time above range were all significantly lower in participants in the low-carbohydrate breakfast intervention group vs those in the control group (all P < .05).

Time in range was significantly higher among participants in the intervention group (P < .05).

In addition, the 2-hour postprandial CGM data showed that mean glucose and maximum glucose after breakfast were lower in participants in the low-carbohydrate breakfast group than in the control group.

This work was supported by investigator-initiated operating grants to senior author Jonathan P. Little, PhD, School of Health and Exercise Sciences, University of British Columbia, from the Egg Nutrition Center, United States and Egg Farmers of Canada. The authors declare that they have no relevant financial relationships.

Am J Clin Nutr. Published online May 29, 2023.

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