An interventional study of Environmental Temperature Exposure in Type 1 Diabetes Mellitus, sponsored by Institut de Recherches Cliniques de Montreal. Not yet recruiting at 1 site in Canada. Open to participants aged 18 Years to 45 Years. Per ClinicalTrials.gov, last updated 2026-03-24.
Sponsored by Institut de Recherches Cliniques de Montreal · Not applicable, Interventional, and Treatment
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:
Researchers will compare three different temperature conditions to see how each affects blood sugar levels and insulin in the body.
Participants will:
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.
Background and Rationale
Climate change is increasing the frequency of extreme weather events, including heat waves and cold snaps. People with type 1 diabetes face higher risks of illness and death during these extreme temperature periods compared to people without diabetes. However, the reasons for this increased risk are not well understood.
When insulin is injected under the skin, it forms a small reservoir from which it gradually enters the bloodstream. Temperature may affect how quickly this insulin is absorbed. Warmer temperatures increase blood flow to the skin, which could speed up insulin absorption and potentially cause blood sugar to drop too low (hypoglycemia). Colder temperatures might slow insulin absorption, leading to higher blood sugar levels (hyperglycemia).
Previous research from the 1980s showed that heating or cooling the injection site affects insulin absorption, but these studies were conducted before modern rapid-acting insulins and diabetes technologies like insulin pumps and continuous glucose monitors were available. No recent studies have examined how whole-body temperature exposure affects insulin absorption and blood sugar control in people with type 1 diabetes.
Study Design Overview
This is a randomized, crossover clinical trial where each participant will experience all three temperature conditions in random order. The study includes:
Study Population
The study will enroll 30 adults aged 18-45 years with type 1 diabetes for at least 2 years. Participants will be equally divided by:
Preliminary Visit Procedures
During the first visit at the Montreal Clinical Research Institute (IRCM), participants will:
Experimental Visit Procedures
Each of the three experimental visits will take place at Centre ÉPIC and follow the same protocol in different temperature conditions:
Pre-Exposure Phase (60 minutes)
Temperature Exposure Phase (120 minutes)
Participants will sit in an environmental chamber set to one of three conditions:
Measurements During Exposure
Continuous monitoring:
Intermittent measurements:
Safety Monitoring
Throughout each visit, research staff will continuously monitor participants for:
Data Collection
24-Hour Activity Logs
Participants will record their food intake, insulin doses, sleep patterns, and physical activity for:
Continuous Glucose Monitoring
A Dexcom G7 sensor will be installed 48-72 hours before each visit to capture:
Laboratory Analyses
Blood samples will be analyzed for:
Special Considerations
For Female Participants Study visits will be scheduled during the follicular phase of the menstrual cycle (or placebo pill phase for those using oral contraceptives) since hormonal changes can affect blood sugar levels.
Insulin Delivery Methods The study will examine whether different insulin delivery methods (injections, pumps, or automated systems) respond differently to temperature changes.
Participant Safety and Comfort
Study Significance
This research will provide the first modern evidence about how environmental temperature affects insulin absorption and blood sugar control in people with type 1 diabetes. The findings could lead to new clinical guidelines for diabetes management during extreme weather events, potentially reducing the increased health risks that people with type 1 diabetes face during heat waves and cold snaps.
The study results may inform recommendations for insulin dose adjustments during temperature extremes and help health care providers better advise patients with type 1 diabetes about managing their condition during increasingly frequent extreme weather events related to climate change.
3,754 studies on the registry are indexed under Diabetes Mellitus, Type 1; 600 are open to participants now.
This study's planned enrollment of 30 is below the median of 40 across 2,820 interventional studies indexed under Diabetes Mellitus, Type 1.
Browse Diabetes Mellitus, Type 1 studies →Institut de Recherches Cliniques de Montreal is the lead sponsor of 61 studies on the registry; 11 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants will be exposed to cold temperature (10°C/50°F) in an environmental chamber for 120 minutes while seated. This temperature is designed to induce shivering thermogenesis and increase energy expenditure by approximately 80%. The cold exposure may slow insulin absorption from subcutaneous injection sites due to reduced skin blood flow and vasoconstriction. Participants will wear standard clothing (shorts and t-shirt) with optional socks and gloves if needed for comfort. Continuous monitoring includes core body temperature via rectal probe, skin temperature at four sites, heart rate, blood pressure every 10 minutes, and blood glucose via continuous glucose monitor every 15 minutes. Blood samples will be collected at baseline, 60 minutes, and 120 minutes for plasma glucose, insulin, glucagon, and metabolic markers. The exposure will be terminated if core body temperature drops to ≤35.5°C.
Other: Environmental Temperature Exposure
Participants will be exposed to neutral room temperature (23°C/73°F) in an environmental chamber for 120 minutes while seated. This condition serves as the control/reference temperature representing typical indoor environmental conditions. At this temperature, normal thermoregulatory responses are minimal, allowing assessment of baseline insulin absorption and glucose responses without temperature-induced physiological stress. Participants will wear standard clothing (shorts and t-shirt) and undergo the same monitoring protocol as other arms: continuous core and skin temperature measurement, heart rate monitoring, blood pressure every 10 minutes, blood glucose monitoring every 15 minutes via continuous glucose monitor, and blood sampling at baseline, 60 minutes, and 120 minutes.
Other: Environmental Temperature Exposure
Participants will be exposed to hot and humid conditions (36°C/97°F with 65% relative humidity) in an environmental chamber for 120 minutes while seated. These conditions simulate a hot summer day in Montreal and are designed to increase skin blood flow through vasodilation, potentially accelerating insulin absorption from subcutaneous depot sites. The combination of heat and humidity will induce thermal stress and sweating responses. Participants will wear standard clothing (shorts and t-shirt) with access to water as needed. The same comprehensive monitoring protocol applies: continuous measurement of core body temperature, skin temperature at four body sites, heart rate, blood pressure every 10 minutes, and blood glucose every 15 minutes. Blood samples will be collected at baseline, 60 minutes, and 120 minutes. The exposure will be terminated if core body temperature reaches ≥39.5°C.
Other: Environmental Temperature Exposure
Systematic 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.
Also known as: Temperature Stress Testing, Thermal Exposure Protocol, Environmental Chamber Study, Ambient Temperature Intervention, Temperature-Insulin Absorption Study
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.
Time frame: Measured at baseline, 60 minutes, and 120 minutes during each 2-hour environmental chamber exposure.
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.
Time frame: Measured at baseline, 60 minutes, and 120 minutes during each 2-hour environmental chamber exposure.
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.
Time frame: 24 hours before and 24 hours after each temperature exposure visit.
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.
Time frame: 24 hours before and 24 hours after each temperature exposure visit.
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.
Time frame: 24 hours before and 24 hours after each temperature exposure visit.
Continuous glucose monitor accuracy
Mean absolute relative difference (MARD) between continuous glucose monitor readings and plasma glucose measurements. This will assess whether temperature conditions affect the accuracy of glucose monitoring technology, which is critical for diabetes management during extreme weather.
Time frame: During each 2-hour temperature exposure.
Plan to share: No
Start is estimated for Mar 2026; primary completion for Mar 2027, 12 months later.
Of 844 non-industry interventional studies with no phase under Diabetes Mellitus, Type 1, half reached primary completion within 19 months of starting (the median), counting those still running; a quarter within 10 and three quarters within 38. This study's planned 12 months is below that.
Counting every sponsor, half of 949 studies reached it within 18 months; a quarter within 9 and three quarters within 35.
How these figures are worked out, and which studies are left out of them.
This study is not yet recruiting, as verified in Mar 2026. You cannot join it, but the record below documents what was studied.
Get an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
Institut de Recherches Cliniques de Montreal