Improving Insulin Sensitivity in Patients With Type 2 Diabetes Via Repeated Cold-induced Shivering Thermogenesis

Overview

Type 2 Diabetes Mellitus (T2DM) is a widespread health condition characterized by impaired ability of the body to maintain glucose homeostasis. This impairment often leads to secondary complications, including heart disease, high blood pressure, and poor quality of life. While exercise and healthy eating are effective strategies in managing and preventing T2DM, data shows that long-term adherence to these methods are poor - especially among elderly, individuals with obesity and/or with physical limitations. This clinical study explores cold exposure with shivering as a novel strategy to improve blood sugar control and heart health. In earlier research, spending time in mildly cold environments (around 15-17°C) for a few hours a day improved insulin sensitivity of T2DM patients. Interestingly, these benefits only occurred when the cold caused mild shivering. In a recent 10-day cold acclimation study with overt shivering for minimally 1 hour/day, we observed improved glucose tolerance in participants with overweight/obesity, as well as improved fasting lipid profiles. These results indicate that when accompanied with sufficient level of muscle activation, repeated exposure to cold can beneficially affect both glucose and lipid levels - both of which are impaired in people with T2DM. In this study, we hypothesise that a 10-day cold acclimation with shivering will improve the (peripheral) insulin sensitivity of patients with T2DM, accompanied by enhanced skeletal muscle FA uptake and oxidation as assessed via the 11C palmitate uptake.

In a longitudinal design, participants will be exposed to a 10-day cold acclimation with daily shivering. Several metabolic read-out parameters will be evaluated before, during and after the intervention. On their first visit (Visit 1) participants will arrive to the research facility to receive a physical activity, ambulatory blood pressure and continuous glucose monitors. Around 48 hours following Visit 1, participants will return (Visit 2) for the baseline two-step hyperinsulinaemic-euglycaemic clamp (HEC) measurement, used to assess their hepatic and peripheral insulin sensitivity. Within 1 week after Visit 2 the acclimation period with 10 consecutive daily shivering sessions will start (Visits 3 - 12). During the first (Visit 3) and last (Visit 12) cold exposure sessions organ-specific fatty acid uptake, and oxidative vs. non-oxidative metabolism will be determined using \[11C\]-palmitate PET/CT. Additionally, indirect calorimetry and regular blood sampling will be performed. During cold exposures 2 to 9, heat loss will be assessed by measuring change in water temperature perfused through the cold exposure suit. In addition, skin temperature, as well as surface electromyography and blood pressure measurements will be performed on days 3, 5, 7 and 9 (Visits 5, 7, 9 and 11) during the acclimation period. On the last cold exposure day participants will be provided a standard dinner to be consumed in the evening before Visit 13. Around 16h following Visit 12, i.e. the day after, participant will return for the post-intervention HEC (Visit 13). At the end of Visit 13, participants will be supplied with an activity and ABP monitors for the post-intervention measuremends. Finally, participants will return to the research centre \~42-45h after Visit 13 for the close-out visit (Visit 14) during which the two monitors will be collected.