Exercise Program Combined or Not With Nutritional intErvention in Adults With tyPe 2 Diabetes

Overview

Inactivity and excess energy consumption are leading causes of obesity and type 2 diabetes which are associated with increased cardio-metabolic risk. In order to reduce the cardiovascular risk associated with type 2 diabetes, the Canadian Diabetes Association guidelines (2008) recommends weight loss through caloric restriction and structured physical activity. However, the comparative effects of different methods to obtain caloric deficit for weight loss remains to be elucidated. The main objective of this study is to assess the impact of two strategies of caloric deficit: diet alone or diet and exercise on total fat mass, epicardial fat and cardiovascular risk factors in overweight and obese adults with type 2 diabetes and at high risk of cardiovascular disease.

Type 2 diabetes is mainly caused by excess body weight due to lack of physical activity and high amount of calories consumption. Individuals with type 2 diabetes demonstrated increased risk of cardiovascular disease compared to non diabetic. Studies showed a cardiovascular risk reduction after weight loss among individuals at risk through lifestyle modification: increase physical activity and low calorie diet. Favourable effects of weight loss on cardiovascular risk are mainly due to total body fat reduction. However, the location of body fat excess has also some important implications. It is now well known that abdominal (visceral) and ectopic fat accumulation (e.g. hepatic fat, epicardial fat, etc.) are more related to an unfavorable cardio-metabolic profile than total fat mass. It has been demonstrated that a moderate weight loss obtained with physical activity or caloric restriction is related to a significant reduction of ectopic fat mass. However, ectopic fat measurement remains problematic due to lack of standardization and safety issues (X-ray). Epicardial fat thickness measured by simple echocardiography is a reliable method to evaluate ectopic fat accumulation. Little research have been done to assess the effect of different methods of weight loss on total fat as well as ectopic fat specifically epicardial adipose tissue among individuals with type 2 diabetes. The objective of this study is to compare to a control group with detailed advice the impact of two structured strategies of caloric deficit: diet alone or diet and exercise on total fat mass, epicardial fat and cardiovascular risk factors in overweight and obese adults with type 2 diabetes and at high risk of cardiovascular disease. The participants to the present study will be free-living adults overweight and obese with type 2 diabetes and at high risk of cardiovascular disease as determined by a Framingham risk score above 15% or the presence of two or more cardiovascular risk factors. Participants will attend a screening study visit to confirm eligibility criteria (anthropometric variables, blood pressure, complete physical examination, coronary heart disease diagnostic by echocardiogram, physical activity aptitude). After enrollment, a baseline visit will consist in series of data collection such as : anthropometric variables, blood pressure, cycle ergometer test to evaluate cardiovascular fitness, an echocardiography to determine epicardial fat thickness, a dual energy x-ray absorptiometry (DEXA) scan to assess body fat, lean mass and bone density, indirect calorimetry for resting metabolic rate, physical activity profile and total energy expenditure determined by Sense Wear Armband (SWA) accelerometer (7days), food consumption estimate with 3 days dairy, questionnaires addressing sociodemographic and psychosocial characteristics, diabetes self-care (SDCA questionnaire), a blood and urine collection for diabetes control, hepatic steatosis biochemical score, detailed lipids, hormonal and inflammatory profile and finally microalbuminuria. The body composition will also be measured by impedancemetry and BOD-POD. Participants will then be randomly assigned to one of the three groups of the study : Group 1: Counseling for physical activity and healthy eating Group 2: Structured diet intervention (caloric restriction) and counseling for physical activity Group 3: Structured diet intervention (caloric restriction) and structured exercise training program (aerobic and resistance training). Group 1: participants will attend one visit with the dietician (30mn) and the physical activity specialist (30mn) when they will be given Canadian guidelines pamphlets for physical activity and food consumption. They will also receive a phone call once a month to discuss about issues in guidelines following. Group 2: participants will attend one visit with the physical activity specialist (30mn) when they will receive the physical activity guidelines. Monthly phone call will be make to discuss about issues in physical activity guidelines following. These individuals will also be enrolled in a supervised caloric restriction program. They will have to visit the dietician once a week for the first months and then twice a month for 3 months. The diet intervention will focus on a low fat diet. At each session participants will be weighed and taken the blood pressure. Group 3: participants will attend diet intervention as described for group 2. They will also follow a supervised exercise program three days per week for 4 months. The exercise training is an interval high intensity aerobic (85-90% Heart rate reserve) program with resistance exercises (15RM, 2-3 repetitions). Each session will last one hour. At the end of month 1, 2, and 3, all participants will receive the SWA armband for 7 days to record physical activity and estimate energy expenditure. At the end of Month 4, all participants will attend a study visit for repeat baseline testing.