The goal of this clinical trial is to learn how different temperatures affect blood sugar levels in adults with type 1 diabetes. Climate change is causing more extreme hot and cold weather, and people with type 1 diabetes may be at higher risk during these temperature changes. The main questions it aims to answer are:
* Do different temperatures (cold, normal, or hot) change blood sugar levels in people with type 1 diabetes? * How does temperature affect insulin absorption in the body?
Researchers will compare three different temperature conditions to see how each affects blood sugar levels and insulin in the body.
Participants will:
* Complete a screening visit with body measurements and questionnaires * Attend 3 separate study visits, each in a different temperature setting: * Cold room (10°C/50°F) * Normal room temperature (23°C/73°F) * Hot and humid room (36°C/97°F with 65% humidity) * Sit for 2 hours in each temperature condition while researchers monitor their blood sugar, heart rate, and body temperature * Wear a continuous glucose monitor for 48-72 hours before each visit * Keep a diary of food, sleep, and activity for 24 hours before and after each visit
Each temperature visit is separated by at least 3 days. The study helps researchers understand if people with type 1 diabetes need special guidance for managing their blood sugar during extreme weather.
Diagnosis of type 1 diabetes for more than 2 years
Ability to provide verbal and written informed consent
Ability to speak and understand French
Recent and/or unstable health condition (less than 3 months) prior to enrolment
Any viral infection at time of participation
Chronic illness other than type 1 diabetes (for example: pulmonary disease, cardiovascular disease, cancer)
Health condition not controlled by medication
Crossover
Environmental Temperature Exposure
Other interventionSystematic exposure to controlled temperature and humidity conditions in a specialized environmental chamber. Each exposure lasts 120 minutes with participants remaining seated throughout. All exposures include standardized pre-exposure preparation (60-minute baseline period at room temperature), continuous physiological monitoring, standardized clothing, and identical blood sampling schedules. Safety protocols include continuous staff supervision, predetermined stopping criteria for extreme body temperatures or blood pressure changes, and immediate availability of warming/cooling interventions and hypoglycemia treatment protocols.
Change in plasma glucose concentration during temperature exposure
The primary outcome is the change in plasma glucose levels (mmol/L) from baseline to end of exposure across the three temperature conditions (cold 10°C, neutral 23°C, hot/humid 36°C). Blood samples will be collected via intravenous catheter and analyzed for plasma glucose concentration. This measure will assess whether ambient temperature affects blood glucose control in individuals with type 1 diabetes, with the hypothesis that cold exposure may increase glucose levels due to slower insulin absorption, while heat exposure may decrease glucose levels due to faster insulin absorption.
Change in plasma insulin concentration during temperature exposure
Change in circulating insulin levels (pmol/L) from baseline across the three temperature conditions. Blood samples collected via intravenous catheter will be analyzed for plasma insulin concentration to assess temperature effects on insulin absorption from subcutaneous injection sites.
24-hour time in glucose range
Percentage of time spent in target glucose range (3.9-10.0 mmol/L) as measured by continuous glucose monitoring (Dexcom G7). This will assess whether temperature exposure has lasting effects on glucose control beyond the immediate exposure period.
24-hour time above glucose range
Percentage of time spent above target glucose range (\>10.0 mmol/L) as measured by continuous glucose monitoring. This measure will identify potential hyperglycemic episodes following temperature exposure.
24-hour time below glucose range
Percentage of time spent below target glucose range (\<3.9 mmol/L) as measured by continuous glucose monitoring. This safety measure will identify potential hypoglycemic episodes following temperature exposure.
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Institut de Recherches Cliniques de Montreal
Lead sponsor
Cardiometabolic Health, Diabetes and Obesity Research Network
Collaborator
Centre EPIC
Collaborator
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