Breaking up Sedentary Time to Improve Glucose Control in a Population at Risk for Developing Type 2 Diabetes

Study Overview
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Brief Summary
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Newly released guidelines recommend increased physical activity (PA) and reduced sedentary behaviors (SB) to improve glycemia and prevent the onset and progression of type 2 diabetes (T2D). Typically, 30-60 min bouts of PA are advocated per day. Although this approach increases PA, it does not decrease the length of the sedentary periods through the day. This is important because recent epidemiological data suggest that frequently interrupting sedentary time improves glucose control even in people who achieve the recommended levels of PA. Preliminary experimental data suggest that breaking up prolonged sedentary time by performing multiple short bouts (5 min) of PA throughout the day, may improve glycemia more than performing a single continuous bout of PA, and thereby potentially be a novel strategy to prevent T2D. The improvement in glycemia was observed even when the total amount of PA and total energy expenditure were matched, suggesting that how and when PA is performed over the day may matter more than how much PA is done. However, important gaps in knowledge remain including: (1) whether similar benefits on glucose control would be observed in adults with prediabetes, a clinically relevant population that is at high risk of developing T2D; (2) whether these effects are sustained or diluted over time, and (3) what are the mechanistic underpinnings. To address these gaps, the investigators propose to measure the acute and chronic effects of PA breaks on glucose control and the underlying mechanisms in individuals at risk of developing T2D. Sedentary men and women with prediabetes (n=66, 50% F) will be randomized to either an intervention designed to interrupt SB with 5-min bouts of brisk walking performed hourly for 9 hours/day, 5 days/week (BREAK) or a control condition consisting of 45-min of brisk walking performed as a single daily continuous bout, 5 days/week (ONE). The two 3-months interventions will be matched for total active time.

Official Title
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Breaking up Sedentary Time to Improve Glucose Control in a Population at Risk for Developing Type 2 Diabetes

Conditions
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Pre-diabetes

Intervention / Treatment
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* Behavioral: BREAK
* Behavioral: ONE


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Male and female BMI of 18.5-40 kg/m2and weight stable over the previous 6 months. Age, 18-64 years old. Fasting glucose of 100-125 mg/dL or fasting HbA1c of 5.7-6.4%, or 2h OGTT blood glucose of 140-199mg/dL based on the American Diabetes Association criteria for pre-diabetes. Less than 150 minutes of moderate-to-vigorous physical activity (MVPA) per week and more than 6 hours of sitting time per day, as self-reported by the volunteers using the IPAQ. Less than 6500 of steps per day as measured by a pedometer over 5 days (at least 1 weekend day). Passing medical and physical screening, and analysis of blood and urine screening samples. Low-moderate caffeine use (<3 cups/day). Agree to refrain from any other structured exercise than the physical activity prescribed in each arm of the study. Agree to eat control diets for 3 days before and during the CTRC visits; Agree to refrain from taking any over-the-counter (including nonsteroidal anti-inflammatory drugs) or prescribed medication (apart from oral contraceptives) for 3 days prior to the inpatient CTRC visits; Agree to wear a Fitbit activity monitor and upload data on the website on a daily basis for the whole duration of the study. Agree to follow the physical activity interventions and to be randomly assigned to one of the two arms of the study. Agree to complete all the study procedures. Exclusion Criteria: Pregnancy, breast-feeding or post-menopause for women. Being considered unsafe to participate as determined by the study physician. Ever having a history of systemic, psychiatric, neurological disease, or drug and alcohol abuse. History of cardiovascular disease, diabetes, uncontrolled hypertension, untreated thyroid, renal, hepatic diseases, dyslipidemia or any other medical condition affecting weight or lipid metabolism. Being positive for human immunodeficiency virus or hepatitis B or C. Taking medications affecting weight, triglycerides, energy intake/energy expenditure, or sleep in the last 3 months. Having abnormal blood chemistry and/or hematology as deemed significant by the study physician. Being a smoker or having been a smoker in the 3 months prior to their screening visit. Having donated over 400 mL of blood within 3 months (90 days) of screening for the study; Working night shifts or traveling across more than 2 time zones within 1 month of and throughout the study. Not completing the trial days of BREAK and ONE during the screening period to assess the willingness and ability of the participant to perform each of the interventions.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 64 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: Participants will be randomized to either the BREAK condition (5-min bouts of brisk walking performed hourly for 9 hours/day, 5 days/wk) or the ONE condition (45-min of brisk walking performed as a single continuous bout, 5 days/wk) for 3 months. Participants will complete all study visits in only one group.
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: BREAK Intervention<br>Participants in the BREAK condition will perform 5-minute bouts of brisk walking hourly for 9 hours/day, 5 days/week for 3 months. | Behavioral: BREAK<br>* The BREAK intervention is a physical activity regimen.<br>|
| Active Comparator: ONE Intervention<br>Participants in the ONE condition will perform 45 minutes of brisk walking as a single continuous bout, 5 days/week for 3 months. | Behavioral: ONE<br>* The ONE intervention is a physical activity regimen.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Glycemia | Plasma glucose concentration in mg/dL measured before and 30, 60, 90 and 120 min after an oral glucose tolerance test (OGTT, 75g glucose). | Glucose concentration in mg/dl, measured at fasting, during a 2 hour OGTT and after | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Insulinemia | Plasma insulin concentration in mUI/mL measured before and 30, 60, 90 and 120 min after an oral glucose tolerance test (OGTT, 75g glucose). | Plasma insulin concentration in mUI/mL, measured at fasting, during a 2 hour OGTT and after | 
| Mean interstitial glucose concentration | Mean interstitial glucose concentration measured continuously by a glucose monitor placed on the tricep for 24hours for 10 days. | Before and after 1 month and 3 months of intervention | 
| Daily glycemia variability | Standard deviation (SD) of interstitial glucose concentration measured continuously by a glucose monitor placed on the tricep 24hours throughout 10 days. | Before and after 1 month and 3 months of intervention | 
| Fasting A1c concentration | Fasting A1c concentration expressed in % | Time Frame: Before and after 1 month and 3 months of intervention | 
| Fasting fructosamine concentration | Fasting fructosamine concentration in umol/L | Before and after 1 month and 3 months of intervention | 
| 12-hour exogenous glucose oxidation | Rates of 13C recovery (% of the dose) in expired CO2 following the ingestion of U-13C-glucose in both breakfast and lunch meals. | Before and after 1 month of intervention | 
| 12-hour endogenous glucose oxidation | Rates of D2 recovery (% of the dose) in expired urines following the infusion of (2,2H2) glucose. | Before and after 1 month of intervention | 
| 12 hour CO2 production | CO2 production measured by indirect calorimetry (ParvoMedics TrueOne 2400, Salt Lake City) for 20 minutes every hour from 0800h to 1800h. | Before and after 1 month of intervention | 
| 12 hour O2 production | O2 production measured by indirect calorimetry (ParvoMedics TrueOne 2400, Salt Lake City) for 20 minutes every hour from 0800h to 1800h. | Before and after 1 month of intervention | 
| 12 Urine excretion | Urine will be measured every hour from 0730h to 1830h | Before and after 1 month of intervention | 
| Glucose kinetics | Steele's equation for non-steady-state will be used to compute RaT and RaE, as well as the rates of disappearance (RdT and RdE) from the percentage of [6,6-2H2]glucose6 and of 13C-glucose in plasma glucose61. EGP will be computed as RaT-RaE. Nonoxidative glucose disposal (NOGD) will be calculated by subtracting total carbohydrate oxidation from (RdT + RdE). Plasma glucose utilization will be assumed to be equivalent to RdT as has been confirmed previously. Muscle glycogen utilization during the active period will be calculated as total carbohydrate utilization during exercise minus plasma glucose utilization during exercise. | Before and after 1 month of intervention | 
| Fasting and postprandial glucose | Fasting and postprandial glucose in mg/dl measured in response to standard lunch | Before and after 1 month of intervention | 
| Fasting and postprandial insulin | Fasting and postprandial insulin in ml/iu measured in response to standard lunch | Before and after 1 month of intervention | 
| Fasting and postprandial C-Peptide | Fasting and postprandial C-peptide nmol/mL measured in response to standard lunch | Before and after 1 month of intervention | 
| Fasting and postprandial glucagon | Fasting and postprandial glucagon in pg/mL measured in response to standard lunch | Before and after 1 month of intervention | 
| Fasting and postprandial catecholamines | Fasting and postprandial catecholamines in pg/mL measured in response to standard lunch | Before and after 1 month of intervention | 
| Skeletal muscle content of protein kinase B (Akt) (Aktser473/total) | Vastus lateralis skeletal muscle biopsies will be collected from fasting participants by the Bergstrom technique. Biopsies will be used to measure protein kinase B (Akt) (Aktser473/total) using western blotting. | Before and after 1 month of intervention | 
| Skeletal muscle content of ACC (ACCS79/ total) | Vastus lateralis skeletal muscle biopsies will be collected from fasting participants by the Bergstrom technique. Biopsies will be used to measure ACC (ACCS79/ total) using western blotting. | Before and after 1 month of intervention | 
| Skeletal muscle content of TBC1D4 (AS160/ total) | Vastus lateralis skeletal muscle biopsies will be collected from fasting participants by the Bergstrom technique. Biopsies will be used to measure TBC1D4 (AS160/ total) using western blotting. | Before and after 1 month of intervention | 
| Skeletal muscle content of COX4 | Vastus lateralis skeletal muscle biopsies will be collected from fasting participants by the Bergstrom technique. Biopsies will be used to measure COX4 using western blotting. | Before and after 1 month of intervention | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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sedentary behavior, physical activity, glucose control, metabolism, pre-diabetes