Managing the rise in blood glucose levels after meals is an important part of managing type 2 diabetes, and can help to reduce the risk of diabetes-related complications, including cardiovascular disease (e.g., heart disease and stroke).
There are many factors which affect post-meal blood glucose levels, including the sensitivity of the body’s cells to insulin, the amount of insulin produced by the pancreas, the amount of glucose taken up by the muscles and glucose production by the liver. These factors vary throughout the day and are controlled by our circadian clock. This means that the glucose response to a meal can differ, depending on the time of the day the meal is eaten. In fact, research has shown that if meal timing isn’t synchronised with our circadian clock, this leads to disruptions in the expression of circadian clock genes (e.g., CLOCK and BMAL1) and is associated with higher post-meal blood glucose levels.
A group of Israeli researchers have been exploring the impact of meal timing on glucose metabolism and weight in people with type 2 diabetes, particularly the role of breakfast. A review of their findings is published in the May 2021 issue of the journal Nutrients.
The researchers have conducted several studies looking at the role of meal timing on blood glucose levels and weight in people with type 2 diabetes and have found the following:
- Skipping breakfast versus eating a high energy/high carbohydrate breakfast influences the expression of clock genes and the rise in blood glucose after subsequent meals, meaning that, on a single day, if you skip breakfast, the rise in blood glucose level is higher after lunch and dinner than if you eat a big, carbohydrate rich breakfast.
- In people with metabolic syndrome, eating a high energy, high carbohydrate breakfast led to a 2-5 fold increase in weight loss over 12 weeks, compared to a high energy high carbohydrate dinner. The post-meal blood glucose response was lower after the big breakfast than the big dinner meal and the overall post-meal glucose levels after meals was significantly lower in the big breakfast compared to the big dinner group.
- In people with type 2 diabetes, eating a larger breakfast versus a larger dinner led to significantly lower overall post-meal glucose levels and glucose excursions (the rise in glucose after eating) across the day.
- In people with type 2 diabetes, compared to a diet of six small meals with energy and carbohydrate spaced across the day, eating three meals with a high energy high carb breakfast and low energy lower carb dinner led to a greater reduction in HbA1c, weight loss, fasting glucose levels and glucose excursions measured using continuous glucose monitoring over 12 weeks.
In each of these studies, the total energy content and composition of the meals and diets was the same in both study groups.
These findings suggest that, independent of what you eat, the timing of your meals may play an important role in blood glucose management, particularly post-meal glucose levels. Our metabolism is best suited to eating in the morning and to fasting and sleeping in the evening. So, the old proverb to “eat breakfast like a king, lunch like a prince, and dinner like a pauper” may well be true.
- Jakubowicz and colleagues. Role of High Energy Breakfast “Big Breakfast Diet” in Clock Gene Regulation of Postprandial Hyperglycemia and Weight Loss in Type 2 Diabetes. Nutrients. 2021
Dr Kate Marsh is an is an Advanced Accredited Practising Dietitian, Credentialled Diabetes Educator and health and medical writer with a particular interest in plant-based eating and the dietary management of diabetes and polycystic ovary syndrome (PCOS).
Contact: Via her website www.drkatemarsh.com.au