Effect of Ambient Temperature on Blood Glucose and Insulin Absorption in Adults With Type 1 Diabetes (T1Temp)

Effect of Ambient Temperature on Insulin Absorption and Change in Blood Glucose Levels in Individuals With Type 1 Diabetes

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.

Study Overview

• Status: Not yet recruiting
• Conditions: Type 1 Diabetes Mellitus
• Intervention / Treatment: Other: Environmental Temperature Exposure

Detailed Description

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:

• 1 preliminary visit for screening and measurements
• 3 experimental visits (cold, neutral, hot conditions)
• Total participation time: approximately 14 hours over up to 4 months

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:

• Sex: 50% male, 50% female
• Insulin delivery method: 10 using multiple daily injections, 10 using insulin pumps, 10 using hybrid closed-loop systems

Preliminary Visit Procedures

During the first visit at the Montreal Clinical Research Institute (IRCM), participants will:

• Review and sign informed consent documents
• Complete medical history and lifestyle questionnaires
• Fill out a heat exposure questionnaire based on Health Canada guidelines
• Complete the GENESIS PRAXY questionnaire to document gender-related factors
• Undergo body measurements including height, weight, waist circumference, and body composition scan
• Have resting heart rate and blood pressure measured
• Receive training on continuous glucose monitor use (if not already using one)

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)

• Participants arrive 2 hours after eating a standardized snack (100g Greek yogurt) with their usual insulin dose
• Body weight measurement
• Installation of rectal temperature probe (self-inserted privately)
• Placement of intravenous catheter for blood sampling
• Attachment of skin temperature sensors, blood pressure cuff, and heart rate monitor
• 60-minute rest period at room temperature to establish baseline measurements

Temperature Exposure Phase (120 minutes)

Participants will sit in an environmental chamber set to one of three conditions:

• Cold: 10°C (50°F) - causes shivering and increases energy expenditure by approximately 80%
• Neutral: 23°C (73°F) - comfortable room temperature
• Hot/Humid: 36°C (97°F) with 65% humidity - simulates a hot summer day in Montreal

Measurements During Exposure

Continuous monitoring:

• Heart rate via chest strap monitor
• Core body temperature via rectal probe
• Skin temperature at four sites (arm, chest, thigh, calf)
• Blood sugar levels via continuous glucose monitor (checked every 15 minutes)

Intermittent measurements:

• Blood pressure every 10 minutes
• Blood samples at baseline, 60 minutes, and 120 minutes for analysis of glucose, insulin, glucagon, and other metabolic markers
• Comfort and sensation ratings every 10 minutes using visual scales for thermal comfort, thermal sensation, and thirst

Safety Monitoring

Throughout each visit, research staff will continuously monitor participants for:

• Signs of hypoglycemia (low blood sugar) - treated immediately with glucose if needed
• Core body temperature limits (stopped if ≤35.5°C during cold or ≥39.5°C during heat exposure)
• Blood pressure limits (stopped if >180/110 mmHg or <90/60 mmHg)
• Participant comfort and willingness to continue

Data Collection

24-Hour Activity Logs

Participants will record their food intake, insulin doses, sleep patterns, and physical activity for:

• 48 hours before the preliminary visit (baseline lifestyle)
• 24 hours before each experimental visit
• 24 hours after each experimental visit

Continuous Glucose Monitoring

A Dexcom G7 sensor will be installed 48-72 hours before each visit to capture:

• Glucose patterns during temperature exposure
• 24-hour glucose control before and after each visit
• Time spent in target range (3.9-10.0 mmol/L)
• Time spent above target (>10.0 mmol/L)
• Time spent below target (<3.9 mmol/L)

Laboratory Analyses

Blood samples will be analyzed for:

• Plasma glucose and insulin levels
• Glucagon (hormone that raises blood sugar)
• Free fatty acids and glycerol (markers of fat metabolism)
• Other metabolic hormones

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

• At least two research staff members will be present during each visit
• One staff member will remain in the environmental chamber with the participant
• Participants can request to stop the exposure at any time
• Emergency procedures are in place for severe blood sugar episodes
• Socks and gloves will be provided during cold exposure if needed

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.

• Study Type: Interventional
• Enrollment (Estimated): 30
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Corinne Suppere, MSc; Phone Number: 514-987-5597; Email: corinne.suppere@ircm.qc.ca
• Study Contact Backup: Name: Jane Yardley, PhD; Phone Number: 514-987-5568; Email: jane.yardley@ircm.qc.ca

Study Locations

• Canada
  • Quebec
    • Montreal, Quebec, Canada, H2W 1R7
      • Institut de recherches cliniques de Montreal

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Diagnosis of type 1 diabetes for more than 2 years
• Ability to provide verbal and written informed consent
• Ability to speak and understand French

Exclusion Criteria:

• 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
• Pregnancy or breastfeeding (for female participants)
• Any other health condition deemed to pose undue health risks during participation in the study

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: None (Open Label)

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Cold exposure; 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; 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.; Other Names: Temperature Stress Testing; Thermal Exposure Protocol; Environmental Chamber Study; Ambient Temperature Intervention; Temperature-Insulin Absorption Study
Active Comparator: Neutral Temperature; 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; 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.; Other Names: Temperature Stress Testing; Thermal Exposure Protocol; Environmental Chamber Study; Ambient Temperature Intervention; Temperature-Insulin Absorption Study
Experimental: Hot/Humid 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.; Other Names: Temperature Stress Testing; Thermal Exposure Protocol; Environmental Chamber Study; Ambient Temperature Intervention; Temperature-Insulin Absorption Study

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
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.	Measured at baseline, 60 minutes, and 120 minutes during each 2-hour environmental chamber exposure.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
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.	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.	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.	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.	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.	During each 2-hour temperature exposure.

Collaborators and Investigators

• Sponsor: Institut de Recherches Cliniques de Montreal
• Collaborators: Cardiometabolic Health, Diabetes and Obesity Research Network; Centre EPIC

Publications and helpful links

General Publications

• Battelino T, Alexander CM, Amiel SA, Arreaza-Rubin G, Beck RW, Bergenstal RM, Buckingham BA, Carroll J, Ceriello A, Chow E, Choudhary P, Close K, Danne T, Dutta S, Gabbay R, Garg S, Heverly J, Hirsch IB, Kader T, Kenney J, Kovatchev B, Laffel L, Maahs D, Mathieu C, Mauricio D, Nimri R, Nishimura R, Scharf M, Del Prato S, Renard E, Rosenstock J, Saboo B, Ueki K, Umpierrez GE, Weinzimer SA, Phillip M. Continuous glucose monitoring and metrics for clinical trials: an international consensus statement. Lancet Diabetes Endocrinol. 2023 Jan;11(1):42-57. doi: 10.1016/S2213-8587(22)00319-9. Epub 2022 Dec 6.
• Stapleton JM, Yardley JE, Boulay P, Sigal RJ, Kenny GP. Whole-body heat loss during exercise in the heat is not impaired in type 1 diabetes. Med Sci Sports Exerc. 2013 Sep;45(9):1656-64. doi: 10.1249/MSS.0b013e31829002f3.
• Wolf, S.T., Havenith, G., Kenney, W.L., 2023. Relatively minor influence of individual characteristics on critical wet-bulb globe temperature (WBGT) limits during light activity in young adults (PSU HEAT Project). Journal of Applied Physiology 134, 1216-1223. https://doi.org/10.1152/japplphysiol.00657.2022
• Taylor, N.A.S., 2014. Human heat adaptation. Compr Physiol 4, 325-365. https://doi.org/10.1002/cphy.c130022
• Singh, N., Areal, A.T., Breitner, S., Zhang, S., Agewall, S., Schikowski, T. and Schneider, A., 2024. Heat and cardiovascular mortality: an epidemiological perspective. Circulation research, 134(9), pp.1098-1112.
• Robine, J.-M., Cheung, S.L.K., Le Roy, S., Van Oyen, H., Griffiths, C., Michel, J.-P., Herrmann, F.R., 2008. Death toll exceeded 70,000 in Europe during the summer of 2003. C R Biol 331, 171-178. https://doi.org/10.1016/j.crvi.2007.12.001
• Ratter-Rieck, J.M., Roden, M. and Herder, C., 2023. Diabetes and climate change: current evidence and implications for people with diabetes, clinicians and policy stakeholders. Diabetologia, 66(6), pp.1003-1015.
• Nakaji, S., Parodi, S., Fontana, V., Umeda, T., Suzuki, K., Sakamoto, J., Fukuda, S., Wada, S. and Sugawara, K., 2004. Seasonal changes in mortality rates from main causes of death in Japan. European journal of epidemiology, 19, pp.905-913.
• Masselot, P., Mistry, M., Vanoli, J., Schneider, R., Iungman, T., Garcia-Leon, D., Ciscar, J.C., Feyen, L., Orru, H., Urban, A. and Breitner, S., 2023. Excess mortality attributed to heat and cold: a health impact assessment study in 854 cities in Europe. The Lancet Planetary Health, 7(4), pp.e271-e281.
• Information CIfH, 2020. Drug use among seniors in Canada.
• Gasparrini A, Guo Y, Sera F, Vicedo-Cabrera AM, Huber V, Tong S, de Sousa Zanotti Stagliorio Coelho M, Nascimento Saldiva PH, Lavigne E, Matus Correa P, Valdes Ortega N, Kan H, Osorio S, Kysely J, Urban A, Jaakkola JJK, Ryti NRI, Pascal M, Goodman PG, Zeka A, Michelozzi P, Scortichini M, Hashizume M, Honda Y, Hurtado-Diaz M, Cesar Cruz J, Seposo X, Kim H, Tobias A, Iniguez C, Forsberg B, Astrom DO, Ragettli MS, Guo YL, Wu CF, Zanobetti A, Schwartz J, Bell ML, Dang TN, Van DD, Heaviside C, Vardoulakis S, Hajat S, Haines A, Armstrong B. Projections of temperature-related excess mortality under climate change scenarios. Lancet Planet Health. 2017 Dec;1(9):e360-e367. doi: 10.1016/S2542-5196(17)30156-0.
• Gasparrini, A., Guo, Y., Hashizume, M., Lavigne, E., Zanobetti, A., Schwartz, J., Tobias, A., Tong, S., Rocklöv, J., Forsberg, B., Leone, M., De Sario, M., Bell, M.L., Guo, Y.-L.L., Wu, C., Kan, H., Yi, S.-M., de Sousa Zanotti Stagliorio Coelho, M., Saldiva, P.H.N., Honda, Y., Kim, H., Armstrong, B., 2015. Mortality risk attributable to high and low ambient temperature: a multicountry observational study. Lancet 386, 369-375. https://doi.org/10.1016/S0140-6736(14)62114-0
• Gallo, E., Quijal-Zamorano, M., Méndez Turrubiates, R.F., Tonne, C., Basagaña, X., Achebak, H. and Ballester, J., 2024. Heat-related mortality in Europe during 2023 and the role of adaptation in protecting health. Nature medicine, pp.1-5.
• Damiano, E.R., El-Khatib, F.H., Zheng, H., Nathan, D.M. and Russell, S.J., 2013. A comparative effectiveness analysis of three continuous glucose monitors. Diabetes Care, 36(2), pp.251-259.
• Costello, A., Abbas, M., Allen, A., Ball, S., Bell, S., Bellamy, R., Friel, S., Groce, N., Johnson, A., Kett, M., Lee, M., Levy, C., Maslin, M., McCoy, D., McGuire, B., Montgomery, H., Napier, D., Pagel, C., Patel, J., de Oliveira, J.A.P., Redclift, N., Rees, H., Rogger, D., Scott, J., Stephenson, J., Twigg, J., Wolff, J., Patterson, C., 2009. Managing the health effects of climate change: Lancet and University College London Institute for Global Health Commission. Lancet 373, 1693-1733. https://doi.org/10.1016/S0140-6736(09)60935-1
• Carter, M.R., McGinn, R., Barrera-Ramirez, J., Sigal, R.J. and Kenny, G.P., 2014. Impairments in local heat loss in type 1 diabetes during exercise in the heat. Medicine and science in sports and exercise, 46(12), pp.2224-2233.
• Bitton, G., Rom, V., Hadelsberg, U., Raz, I., Cengiz, E., Weinzimer, S. and Tamborlane, W.V., 2019. Effect of injection site cooling and warming on insulin glargine pharmacokinetics and pharmacodynamics. Journal of Diabetes Science and Technology, 13(6), pp.1123-1128.
• Ballester, J., Quijal-Zamorano, M., Méndez Turrubiates, R.F., Pegenaute, F., Herrmann, F.R., Robine, J.M., Basagaña, X., Tonne, C., Antó, J.M., Achebak, H., 2023. Heat-related mortality in Europe during the summer of 2022. Nat Med 29, 1857-1866. https://doi.org/10.1038/s41591-023-02419-z

Study record dates

Study Major Dates

• Study Start (Estimated): March 1, 2026
• Primary Completion (Estimated): March 1, 2027
• Study Completion (Estimated): July 1, 2027

Study Registration Dates

• First Submitted: March 18, 2026
• First Submitted That Met QC Criteria: March 18, 2026
• First Posted (Actual): March 24, 2026

Study Record Updates

• Last Update Posted (Actual): March 24, 2026
• Last Update Submitted That Met QC Criteria: March 18, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: Hypoglycemia; Type 1 diabetes; Continuous glucose monitoring; Blood glucose; Insulin absorption; Temperature exposure
• Additional Relevant MeSH Terms: Endocrine System Diseases; Metabolic Diseases; Autoimmune Diseases; Immune System Diseases; Glucose Metabolism Disorders; Diabetes Mellitus; Nutritional and Metabolic Diseases; Hypoglycemia; Diabetes Mellitus, Type 1
• Other Study ID Numbers: 2026-1330

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No