Reducing blood glucose extremes caused by food and exercise in type 1 diabetes

How do different types of food and exercise affect the blood sugar of young people with type 1 diabetes in day to day life?

For people with type 1 diabetes, everyday activities such as exercise and eating can cause unpredictable fluctuations in blood glucose levels, increasing the risk of dangerously low blood glucose (hypoglycaemia) and long-term complications. These fluctuations can be incredibly frustrating, and the fear of hypoglycaemia means that many people with type 1 diabetes are reluctant to participate in physical activity.

Professor Liz Davis from the University of Western Australia is leading the T1DCRN funded research program that aims to improve our understanding of how blood glucose is affected by exercise and food in real-life situations.

Exercise can have a varying effect on the blood glucose levels which can be difficult to anticipate. Many factors play a role including the type of exercise, the time of day when exercise is performed, the amount of carbohydrate eaten, the blood glucose level before exercise and the amount of insulin administered.

Food also has a major effect on blood glucose control in diabetes. Currently, only carbohydrates are taken into account when estimating the appropriate amount of insulin to take. However protein and fat also raise blood glucose levels which can cause errors in insulin dose and unpredictable blood glucose levels.

Professor Davis and her collaborators will study these different variables and their impact on blood glucose in young people with type 1 diabetes, with the aim of developing new guidelines for managing food and exercise. They hope that using these guidelines will result in lower hypoglycaemia risk, more stable blood glucose levels, reduced fear and anxiety about hypoglycaemia, and increased quality of life in people with type 1 diabetes.

More information about the project will be released when available.

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Technical Summary
Strict blood glucose management in T1DM is crucial for the prevention of hypoglycaemia and the many long-term diabetic complications associated with chronic hyperglycaemia. This is challenging however, as both exercise and meals often result in hyperglycaemic and hypoglycaemic glucose excursions. This research aims to identify gaps in current knowledge around insulin dosing and food/exercise in order to develop new guidelines. The research has two components. The first and largest component addresses approaches to assist patients with type 1 diabetes to exercise more safely. The second component addresses gaps in knowledge concerning diet in type 1 diabetes. For both components, identified gaps in knowledge will be addressed through in-clinic studies that address specific questions.

Trial Design Component 1 – Exercise
  • Study 1: Fifty adolescents and young adults will be recruited to this randomised clinical trial to investigate the effect of incorporating 10-second sprints into any sustained period of physical activity for the prevention of exercise-mediated hypoglycaemia in individuals with type 1 diabetes in a free-living setting. This study has been previously funded through a NHMRC grant and is not funded by the T1DCRN.
  • Study 2a: 12 adolescents and young adults with type 1 diabetes will exercise for four 40 min sessions at 35%, 50%, 65% or 80% V̇O2 peak (or until exhaustion) under basal insulin conditions. The glucose requirement to maintain blood glucose levels of 5 – 6 mmol/l during exercise of different intensities will be determined.
  • Study 2b: This study is identical to Study 2a except exercise will be performed under hyperinsulinaemic conditions. The data obtained from Study 2a and 2b will then be used to determine the oral intake of carbohydrate (CHO) required for the prevention of hypoglycaemia associated with exercise of different intensities under differing insulinaemic conditions. The reproducibility of blood glucose responses will then be measured in 10 adolescents and young adults with type 1 diabetes. Participants will exercise in four sessions, two in the morning and two in the afternoon under basal insulin conditions.
  • Study 3: Revised guidelines will be developed through a series of focus groups that engages patients with T1D, their carers and health care providers, both in Australia and the United States, to ensure their utility and adoption.
  • Study 4: A multi-centre randomised controlled trial (RCT) with 100 participants will be conducted within the metropolitan area of Perth, Western Australia to test the efficacy of the guidelines developed. Eligible participants will be randomly assigned to either an intervention group, who will follow the new guidelines or a control group who will receive their current standard of clinical care.
Component 2 – Food
Consumption of meals high in protein and/or fat results in delayed hyperglycaemia, and difficulty in determining the insulin dose and delivery pattern. In-clinic clamp studies will investigate how much additional intravenous insulin is required for a meal high in protein or a meal with high protein/high fat. Using this data and data from previous studies, a novel algorithm for determining insulin dose for high protein and high protein/fat meals will be derived. A focus group will workshop the preferred format and utility of the new advice on insulin dosing with meals. The revised algorithm will then be trialled in a randomised controlled crossover trial with 40 participants on continuous subcutaneous insulin infusion (or just insulin pumps?) in Newcastle and Perth. Additionally, to define the relationship between CHO quantity and the dose of insulin an evaluation of linear versus non-linear Insulin and carb ratio will be undertaken.

Principal Investigator
Associate Professor Elizabeth Davies

The Australian Type 1 Diabetes Clinical Research Network NHMRC – Component 1, Study 1 only Infrastructure support is provided through an NHMRC/JDRF Centre of Research Excellence Grant, as well as funding for students and training.

  • Western Australia
    • Princess Margaret Hospital
    • Royal Perth Hospital
    • Fiona Stanley Hospital
    • Sir Charles Gairdner Hospital
  • NSW
    • John Hunter Children’s Hospital
Primary Endpoints
Component 1
  • In-Clinic Studies: The glucose infusion rate required to achieve euglycaemia during exercise performed under basal and hyperinsulinaemic conditions and the multiple of intravenous glucose requirements that determine oral CHO requirements.
  • The plasma glucose levels during exercise and for 2 hours afterwards.
  • RCT: The incidence of hypoglycaemic events (assessed by CGMS readings, blood glucose readings, and symptoms of hypoglycaemia).
Component 2
  • The total amount of IV insulin (units) titrated to maintain blood glucose levels at 5.0 mmol/L after intervention meal compared to the control meal.
  • Glucose excursions at 30 minute intervals for up to 6 hours following the different insulin dosing algorithms.
  • Postprandial hypoglycaemic events defined as BGL less than 3.9 mmol/L.
Secondary Endpoints
Component 1:
  • Insulin levels during exercise and for 2 hours afterwards.
  • Time spent within glycaemic ranges assessed by CGMS e.g. 4-8 mmol/L; 8-12 mmol/L; >12 mmol/L.
  • Correlation of physical activity (activity counts and heart rate) with glucose levels.
  • Adherence with the guidelines (intervention group), ease of guideline use.
  • Mental health and quality of life.
  • Health economic measures.
Component 2:
  • Pattern of insulin delivery in the 5 hour study period and gastrointestinal hormones levels.
  • Hypoglycaemic events in the 6 hour postprandial period, peak glucose excursion and time to peak glucose excursion.
  • Area Under the Curve (AUC) of postprandial glucose excursion.
Inclusion/Exclusion Inclusion Criteria
  • Component 1: People with T1D between 15-30 years old, with HbA1c levels <10% and with no evidence of diabetes complications
  • Component 2: Healthy people with T1D > 1 year, between 12 – 21 years old, HbA1C < 8% BMI ≤ 97th percentile
Start/End Date 2016 – 2019