Glucose variability in T1D and glycaemic response to food composition
Research type
Research Study
Full title
An investigation into diurnal variability in glucose levels in paediatric patients with Type 1 Diabetes (T1D) and their responses to different food compositions.
IRAS ID
273640
Contact name
Stuart D R Galloway
Contact email
Sponsor organisation
University of Stirling
Duration of Study in the UK
1 years, 5 months, 1 days
Research summary
Research Summary
Type 1 diabetes (T1D) is caused by a lack of insulin production, whose main role is to regulate blood glucose levels. Treatment involves administration of insulin with the aim to achieve glucose levels close to normal range, however many children and young people with T1D find their glucose levels often fluctuate well above and below this. High levels in the daytime is mainly caused by food intake and appears worse after breakfast. As blood glucose levels are often only checked before meals, rather than after, there is limited evidence of how often fluctuations occur, and there is little evidence of how high levels after breakfast may be better managed through diet.
It is possible to obtain more detailed information about glucose levels by using continuous glucose monitoring (CGM) systems. This study proposes recruiting children/young people who have T1D and use CGM. Participants will be asked to provide both retrospective and on-going CGM data. The participants will then be asked, for seven days, to provide photographs and information on their breakfast, morning activities and insulin doses. These data will be statistically described to establish the extent of glucose variability and postprandial hyperglycaemia after breakfast and results will be compared between participants and food composition at breakfast.Summary of Results
We wish to thank the children and young people (CYP) and their families for taking part in the study.
General information about the studyThe study title:
An investigation into diurnal variability in glucose levels in paediatric patients with Type 1 Diabetes (T1D) and their responses to different food compositions.Who carried out the research:
The research was carried out by the University of Stirling as part of a clinical doctorate which was funded by the University of Stirling and NHS Highland. The sponsor was the University of Stirling. We planned to recruit children and young people who had type 1 diabetes (T1D) to the study.Where and when the study took place:
We received ethical approval for the study in November 2020. We recruited participants from February to November 2021.Why the research was needed
The researcher had worked with CYPs with T1D as a dietitian for many years. It was noted that glucose levels can be variable, and CYPs with T1D often experience high glucose levels after breakfast. This is known as the breakfast spike. There appeared to be limited evidence about how best to manage this.The main research questions:
We wanted to find:
• How out how variable the glucose levels were in the day and night-time.
• What the CYPs ate for breakfast and how variable glucose levels were for 4-hours after breakfast.
• This was an observational study; we didn’t ask the children to make any changes to their usual breakfast meals or routines.Who participated in the study?
• 96 CYPs with T1D were recruited to the study.
• The participants were invited to share their Dexcom CGM data (this records glucose levels in the tissue fluid every 5mins); 88 of the participants were invited to provide information about their breakfast meal; 8 participants were recruited to provide CGM data only.
Characteristics of the participants
• 45.8% were female, average age was 10.2 years, average years of having T1D was 4.2 years.
• 76.8% of the participants used insulin pumps to manage their diabetes; the remaining 23.2% used multiple daily injections (MDI).
• 30% met the target for HbA1c (gold standard measure of diabetes control)
What happened during the study?
• 89 participants shared their CGM data: of these 74 provided information on their breakfast meal and the 4-hour period after breakfast was ingested
• The questionnaires were received over an average of 5.8 days.
• Some breakfast meals were excluded as there was missing CGM data. 387 breakfasts were analysed; 337 corresponding post breakfast period questionnaires were received.
• The breakfast meals were analysed for their nutrient content as well as glycaemic index and glycaemic load.
• The glycaemic index is a measure of how quickly carbohydrate foods raise the level of glucose in the blood; it is based on a scale of 0-100. The higher the food is ranked on the scale the faster the glucose levels are expected to rise in the blood. Glycaemic load is a calculation based on the GI of the food and the amount of carbohydrate in the food. The GL has three categories of low, medium and high.The results of the study:
Key findings from the analysis of the CGM data:• The average glucose readings over 24hours for all the participants collectively was 9.3mmol/l and within the recommended target of 3.9-10mmol/l which is classed as being ‘in range’. The more time the CYP spend with their glucose in range the less likely they are to develop complications of diabetes.
• The time spent in range is often calculated as a percentage. It is recommended for people with T1D to spend to least 70% of their time in range. The average amount of time spent in range for all the participants collectively was 60.1%. The average time was therefore less than the recommendation. 24.7% of the participants met the target for time spent in range.
• Those participants who used insulin pumps spent significantly more time in range than those using injections.
• Glucose variability is measured as a percentage; the recommended target is to have a glucose variability of 36% or below. A high glucose variability means that glucose levels are going up and down a lot; this may increase the risk of developing complications. 36% of the participants had a glucose variability in target. The average glucose variability for all the participants collectively was 37.8%. This was significantly higher in the daytime than nighttime.
Key findings of the breakfast meals:
Before breakfast
• The average reading before the breakfast meal collectively for all breakfasts was 8mmol/l; this met the recommended target for fasting glucose of 4-8mmol/l. 41.7% of the breakfasts involved a glucose reading above 8mmol/l before the meal began. It is important to have a glucose within target especially before eating as in T1D there will always be a meal rise and the higher the glucose before the meal the higher the glucose might become after the meal.
• The pre breakfast reading was significantly lower for the meals managed with insulin pumps.
• As many meals were above the target 46.9% of meals involved a correction dose of insulin for a high reading. A correction dose in given to lower the glucose into target. The chance of needing a correction dose was greater for meals managed with injections
After breakfast
• The average glucose of all the breakfasts collectively over 4hours after ingestion of breakfast was 9.2mmol/l; this is within the target range of 3.9-10mmol/l. The post breakfast reading was in target for 67.7% of the meals.
• The 4hr post breakfast reading was significantly higher than the pre breakfast reading.
• We found that the higher the pre breakfast reading was the higher the post breakfast reading was likely to be.
• The average post breakfast reading was significantly lower for meals managed with pumps.
• 21.2% of the breakfasts needed a correction dose of insulin within the 4-hour post breakfast period.
The breakfast meal
• 65.4% of breakfasts had a high glycaemic load. High glycaemia loads cause the glucose levels to rise and in people without diabetes it causes a lot of insulin to be released in the body.
• 49.8% of meals contained a breakfast cereal. The breakfast cereals in this study had an average glycaemic index that fell into the ‘high ‘category.
• The time glucose levels took to reach their highest levels was significantly faster for the high GL meals and for meals that only included breakfast cereals
• Breakfast’s that only contained breakfast cereal resulted in significantly more glucose variability and more time above range after meals that include only breakfast cereals
• As carbohydrate intake increased so did the average post meal reading, and the time spent above target. As fat intake increased the time to peak to highest level increased.
• The time spent very high (above 13.9mmol/l) was significantly shorter after meals that included a protein food.
• Snacks in the 4-hour post meal period did not cause a rise in glucose levels if the participant was active
• Physical activity significantly reduced the time spent above 13.9mmol/l
How has the study helped?
The study has helped learning about glucose variability and the breakfast meal in CYPs with T1D. The results have shown that:
• CYPs need support to meet the recommended glucose targets.
• CYPs need support to better manage glucose variability particularly in the daytime
• The study provides evidence that the breakfast spike does exist; but more half of meals did not result in a higher than target reading
• CYPs need support to ensure the pre-breakfast reading is in target wherever possible to reduce post breakfast spikes
• All CYPs need to be given access to technology e.g. CGM to help evaluate their glucose levels
• All CYPs should be offered insulin pumps
• CYPs need to be supported to make good quality choices at breakfast in regards the GI of the food, the fibre content and the GL of the meal
• Activity in the postprandial period needs to be encouraged
• The impact of glycaemic load and additional of a protein food to the breakfast meal needs further investigation of effectiveness but also of the acceptance of this to CYPs/families.Further planned research:
Further research is now being undertaken in phase 2 of this study. This is an intervention study of randomized crossover design involving different test meals at breakfast with the participants acting as their own controls. Contact details for further information: Chief Investigator: Julie Johnson, Registered dietitian & Clinical Doctorate Student, University of Stirling, julie.johnson1@stir.ac.ukREC name
West of Scotland REC 5
REC reference
20/WS/0123
Date of REC Opinion
23 Sep 2020
REC opinion
Favourable Opinion