Weight Change During Diet and Exercise Interventions Among Overweight Adults with Type 2 Diabetes: Results of a Chart Review

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1 weight change and interventions 255 original research Weight Change During Diet and Exercise Interventions Among Overweight Adults with Type 2 Diabetes: Results of a Chart Review Golyar Keyhan 1 MD FRCPC, Elham Rahme 2 PhD, Steven Grover 2,3 MD MPH, Kaberi Dasgupta 1,2,3 MD MSc FRCPC 1 Division of Endocrinology and Metabolism, Department of Medicine, McGill University, Montreal, Quebec, Canada 2 Division of Clinical Epidemiology, Department of Medicine, McGill University, Montreal, Quebec, Canada 3 Division of General Internal Medicine, Department of Medicine, McGill University, Montreal, Quebec, Canada ABSTRACT Objective: To compare weight change between clinical Trial and Program participants enrolled in a 24-week dietary counselling and supervised exercise program at a cardiac rehabilitation centre. Methods: For the period between January 2003 and December 2004, the following data were abstracted from clinic/trial charts: weight (baseline, 12 weeks, 24 weeks), age, sex, use of antihyperglycemic medication, glycated hemoglobin (A1C), fitness level and exercise class attendance. Weight change over 24 weeks, expressed as a percentage of baseline weight, was compared between groups in unadjusted and adjusted models. Results: Trial (n=18) and Program (n=18) participants were similar in terms of age, obesity, fitness and A1C. The proportion of women was somewhat lower in the Program group, and fewer Program participants reported the use of antihyperglycemic medication. Program participants attended a nonsignificantly higher number of exercise classes (45 vs. 39 sessions) and demonstrated significantly greater weight change ( 4.2% [SD 3.5] vs. 1.4% [SD 2.8], p=0.05) not explained by other measured variables. Conclusions: Weight loss by Program participants suggests that a 24-week diet and exercise program may potentially achieve more weight loss than suggested by our original clinical trial. Possible reasons for between-group differences are discussed. Keywords: diet, supervised exercise, type 2 diabetes, weight loss RÉSUMÉ Objectif : Comparer le changement de poids entre les sujets d un essai clinique et les participants à un programme de 24 semaines offert dans un centre de réadaptation cardiaque et comportant une thérapie nutritionnelle et un programme d exercices supervisé. Méthodes : De janvier 2003 à décembre 2004 les données suivantes ont été extraites des dossiers des patients : poids (au départ et 12 et 24 semaines plus tard), âge, sexe, prise d un antihyperglycémiant, hémoglobine glycosylée (HbA 1c ), condition physique et assiduité aux séances d exercices. Le changement de poids au cours des 24 semaines, exprimé en pourcentage du poids initial, a été comparé entre les groupes dans des modèles rectifiés et non rectifiés. Résultats : Les sujets de l essai (n = 18) et les participants au programme (n = 18) étaient semblables en ce qui a trait à l âge, l obésité, la condition physique et l HbA 1c. Le programme comptait légèrement moins de femmes que l essai clinique et un moins grand nombre de participants au programme que de sujets de l essai ont signalé avoir pris un antihyperglycémiant. Les participants au programme ont assisté à un plus grand nombre de séances d exercices (45 par rapport à 39, différence non significative) et leur poids a changé significativement plus que celui des sujets de l essai clinique (-4,2 % [ET : 3,5] par rapport à -1,4 % [ET : 2,8], p = 0,05), ce qui n a pu être attribué à aucune autre variable mesurée. Address for correspondence: Kaberi Dasgupta, Division of Clinical Epidemiology, McGill University Health Centre 687 Pine Avenue West, V Building, Room V1.08, Montreal, Quebec, Canada H3A 1A1 Telephone: (514) , ext , Fax: (514) , kaberi.dasgupta@mcgill.ca

2 256 CANADIAN JOURNAL OF DIABETES Conclusions : La perte de poids chez les participants au programme semble indiquer qu un programme de 24 semaines comportant une thérapie nutritionnelle et des exercices pourrait réduire le poids davantage que notre essai clinique original le laissait supposer. Cet article traite des raisons possibles des différences entre les groupes. Mots clés : thérapie nutritionnelle, programme d exercices supervisé, perte de poids, diabète de type 2 INTRODUCTION Among overweight adults with type 2 diabetes, weight reduction of as little as 5% may result in improved blood pressure, lipid profile and glycemic control (1,2). More importantly, a large cohort study suggests that intentional weight loss in this population is associated with a 30% reduction in cardiovascular mortality more than 10 years later (3). Nonetheless, weight loss remains a challenge. Through a clinical trial conducted at a cardiac rehabilitation centre in Montreal, Quebec, Canada (4), we demonstrated that dietary education combined with supervised exercise was associated with better blood pressure control than dietary education alone over 24 weeks among adults with type 2 diabetes not receiving insulin treatment. However, although exercise class participants realized important improvements in fitness, little weight change was achieved in either treatment arm ( 0.3% with dietary education alone; 1.2% combined dietary education and supervised exercise) (4). The centre where the trial interventions were conducted (Cardiovascular Health Improvement Program [CHIP], had an existing fee-based program also targeting diabetes patients and involving an identical exercise intervention. The schedule of dietary counselling sessions was also similar, but while Trial participants received dietary education based on Canadian Diabetes Association (CDA) guidelines, Program participants were offered instruction in a lower-carbohydrate (Montignacstyle) approach, a dietary education strategy used at the centre for many years. In the present analyses, we compared weight change among Trial participants to that of Program participants and attempted to determine whether any observed differences were attributable to demographic/ clinical profiles and/or class attendance. We present the results of these analyses and discuss other factors that may have played a role in weight-loss differences. Our overarching objective is to move toward more effective weight-loss programs for people with type 2 diabetes. METHODS Program and Trial interventions In January 2003, a 24-week diet and exercise program was launched at CHIP targeting adults with diabetes. In contrast to existing 12-week programs at CHIP for patients with established cardiovascular disease, the diabetes program was offered over a 24-week period and involved: (i) individualized dietary education with a registered dietitian once every 4 weeks (145 minutes total education time); and (ii) 48 group supervised exercise sessions (6 to 10 patients per group). Trial participants received dietary education based on the 1998 CDA guidelines (5), with an emphasis on lessrefined carbohydrates, low fat content, balanced meals and attention to portion size. Program participants followed a dietary strategy adopted over the previous 10 years at CHIP that included some food intake every 3 hours while awake, preferential selection of lower glycemic index (GI) carbohydrates (GI <50) and a Montignac-style strategy (6) that discouraged concurrent intake of fat and medium glycemic index carbohydrates during a given meal or snack (Table 1). For both Trial and Program participants, exercise sessions were conducted at a frequency of 3 times per week for the first 8 weeks, 2 times per week for the next 8 weeks and once per week for the final 8 weeks (a total of 48 sessions). The philosophy underlying the exercise session schedule was to gradually permit participants to shift from supervised sessions to unsupervised sessions so that by the end of the program they would be able to exercise at a gym or at home without supervision. All participants underwent an exercise stress test and medical evaluation prior to commencing the exercise intervention in order to identify undiagnosed or poorly controlled ischemic heart disease and permit the calculation of an individualized exercise heart rate target. Table 1. Summary of general principles followed for Montignac-based dietary counselling during the program Total carbohydrate consumption Starchy carbohydrate Fruits Fats Protein Not specifically reduced, but concurrent consumption of grains and fats during same meal or snack discouraged Consumption of low glycemic index foods encouraged Permitted half an hour before meals Not specifically reduced but concurrent consumption of grains and fats during same meal or snack discouraged Higher intakes permitted

3 weight change and interventions 257 During exercise sessions, participants were monitored with a polar heart rate monitor and encouraged to maintain a heart rate of 65 to 85% of the maximal heart rate safely achieved during the stress test. Sessions involved small groups (8 to 10 participants) supervised by an exercise physiologist and included 45 minutes of cardiovascular exercise (treadmill, bicycle, cross-trainer) and 15 minutes of stretching. Data collection For the present analysis, a chart review was conducted for all Program participants not on insulin enrolled in the CHIP diabetes program between January 2003 and December A database and chart review was conducted for all Trial participants who engaged in a dietary education and supervised exercise program between September 2003 (when trial procedures commenced) and December During the trial, as previously described, participants were randomized to dietary education alone or combined with supervised exercise. After the final trial assessments were completed in April 2004, Trial participants who had been randomized to dietary education alone were offered a supervised exercise program as thanks for their participation. All Trial and Program participants who participated in at least 1 supervised exercise session were eligible for inclusion in the present analysis. Although requiring attendance at more supervised exercise sessions may have strengthened any observed association between weight loss and exercise-class attendance, we believed that a more conservative intent to treat type of approach was the preferable way to analyze the available data, particularly with respect to comparisons between Trial and Program participants. The following data were abstracted: body weight (baseline, 12 weeks, 24 weeks), antihyperglycemic medication use at baseline (none, metformin, sulfonylurea), glycated hemoglobin (A1C), age, sex, workload achieved during exercise stress test (fitness level) and number of exercise sessions completed. Ethical approval for both the chart review and the original clinical trial was obtained from the Institutional Review Board at McGill University. The process of chart review was also approved by the Commission d Accès a l Information (Quebec government). Analysis of weight change All statistical analyses were performed using SAS version 9.1 (SAS Institute, Cary, NC). Change in weight was expressed as a percentage of baseline weight and was calculated for weeks 1 to 12, weeks 12 to 24, and weeks 1 to 24, with week 1 defined as the first week of the supervised exercise program. For example, change in weight between baseline and week 12 was calculated as [(weight at week 12) (weight at baseline)]/weight at baseline] x 100. Participants who withdrew prior to week 12 and had no weight recorded after week 1 were excluded from the present analysis. For those who withdrew between weeks 12 and 24, the week 12 weight value was carried forward. Program and Trial participants were compared for each of the time intervals assessed, and exercise class attendance was compared between groups (t-tests). For weight change between weeks 1 and 24, weight change between Program and Trial participants was compared using a linear regression model. Potential covariates assessed included age, sex, A1C, use of metformin (yes/no), use of a sulfonylurea (yes/no), fitness level and number of dietary counselling and supervised exercise sessions attended. Age, sex and potential covariates that appeared to differ between groups were tested in multivariate models. Because of the sample size, no more than 4 potential determinants/predictors were concurrently included in a given model to ensure a ratio of approximately 10 subjects per potential determinant/predictor. RESULTS Participants Nineteen Program participants and 21 Trial participants commenced a program of dietary counselling and supervised exercise at CHIP between January 2003 and November One Program participant (5%) and 3 Trial participants (14%) had withdrawn by week 12. Two more Program participants (11%) and 2 more Trial participants (10%) withdrew between weeks 12 and 24. Data from 36 participants were included in the analyses reported below. As previously reported (4), the primary reasons for withdrawal during the trial were work and family responsibilities. Reasons for program withdrawal were not recorded. There were no significant baseline differences between groups. Participants were middle-aged and obese (Table 2). Baseline fitness levels were similar between groups. A higher proportion of Program participants were men. A1C levels were consistent with acceptable glycemic control in both groups, but a greater proportion of Trial participants reported use of antihyperglycemic medication. Attendance and weight change Participants in both groups attended an average of 5 out of 6 dietary education sessions. There was no significant difference in exercise session attendance between groups. Exercise session attendance was nonsignificantly higher between weeks 1 and 12 (26 sessions [SD 11] for Program vs sessions [SD 7] for Trial) and between weeks 12 and 24 (19 sessions [SD 8] for Program vs. 16 sessions [SD 7] for Trial). Weight change did not differ significantly between Program and Trial participants between weeks 1 and 12 ( 3.1% [SD 3.3] in Program vs. 1.7% [SD 3.1] in Trial, p=0.3), but was significantly greater among Program

4 258 CANADIAN JOURNAL OF DIABETES participants between weeks 12 and 24 ( 1.2% [SD 1.9] in Program and 0.3% [SD 1.7] in Trial, p=0.03) (Figure 1). Net weight change at 24 weeks was also higher among Program participants ( 4.2% [SD 3.5] in Program and 1.4% [SD 2.8] in Trial, p=0.05). As calculated through a linear regression model, Program participants lost 2.6% more of their baseline weight by week 24 (p=0.04) compared to Trial Table 2. Baseline characteristics Characteristic All (n=36) Trial participants (n=18) Program participants (n=18) Age, y* 54.3± ± ±13.7 Men, n (%) 20 (55) 9 (50) 11 (61) BMI, kg/m 2 * 36.4± ± ±5.6 A1C, %* 6.9± ± ±1.5 Fitness level, METs* 8.3± ± ±2.3 Taking metformin, n (%) 22 (61) 16 (89) 6 (33) Taking a sulfonylurea, 11 (30) 8 (44) 3 (17) n (%) *Values are mean±sd Workload achieved during maximal exercise stress test A1C = glycated hemoglobin BMI = body mass index MET = metabolic equivalent Figure 1. Change in weight for Trial and Program participants Change is weight (% baseline) Trial participants Program participants Weeks 1 to 12 Weeks 12 to 24* Weeks 1 to 24* *Percentage change from baseline was significantly different between Trial and Program participants, p 0.05 participants. No other variable examined was significantly associated with weight change. DISCUSSION During a 24-week program of dietary education and supervised exercise, neither the Program nor Trial participants achieved the 5 to 10% initial weight loss target recommended for overweight adults with type 2 diabetes (1,2). However, Program participants were closer to this goal, with a 4% net weight reduction compared to Trial participants, who achieved less than a 2% weight reduction. Although both groups lost weight during the first 12 weeks of the program, only Program participants continued to lose weight during the final 12 weeks. At baseline, Program and Trial participants were similar in terms of glycemic control, although Trial participants tended to use more glucoselowering medication. Multivariate testing did not identify a specific clinical or demographic variable to be associated with weight change (e.g. age, sex, A1C, use of glucose-lowering medication). Dietary education class attendance was similarly high in both groups. Although Program participants attended more exercise classes than Trial participants, the difference in attendance was not statistically significant. Our analysis suggests that a real-world 24-week program of dietary education and supervised exercise may indeed be associated with weight change approaching the initial 5% target loss among overweight adults with type 2 diabetes. It is not clear why such weight change was not achieved among Trial participants. The between-group difference could not be explained by differences in age, sex, glycemic control or fitness level. Although not statistically significant, the Program participants appeared to have a somewhat higher rate of exercise class attendance. There is also a possibility that differences in dietary counselling may in part have accounted for the between-group difference. The issues of attendance and dietary counselling are discussed briefly below. Although we cannot be certain, it is possible that with a larger number of participants in each group, a statistically significant between-group difference in exercise class attendance may have emerged. We speculate that such a difference might be attributable to either (i) unmeasured socioeconomic differences between the groups or (ii) greater financial investment by Program participants. Higher socioeconomic status may arguably be associated with greater access to resources permitting class attendance (e.g. transportation, flexible work hours, child care resources). With respect to financial investment, as previously noted, Trial participants received interventions free of charge, while Program participants paid for dietary education and supervised exercise services. Financial incentives have previously been demonstrated to favourably impact exercise class attendance and weight loss. In one study, walking program

5 weight change and interventions 259 participants randomized to an incentive strategy ( $3 per session) attended more exercise sessions (65.8 vs. 35 sessions) and had greater weight loss ( 4.5 vs. 3.8 kg) at 18 months compared to those randomized to a program without incentives (7). The difference in dietary education approaches is also of interest. An increasing number of studies suggest that a lower-carbohydrate dietary approach in type 2 diabetes may be associated with greater weight loss, as recently reviewed by Arora and McFarlane (8). The Montignac dietary strategy employed by the CHIP program may be considered a form of low-carbohydrate diet. In a 2-week crossover trial (Montignac vs. American Heart Association diet), this approach was demonstrated to result in increased satiety, reduced energy intake (8815 vs joules), reduced carbohydrate intake (37 vs. 55%) and increased protein intake (31 vs. 15%) (9). Total fat intake was similar (32 vs. 30%) (9). Investigators attributed the increased satiety to the increase in protein intake (9). We must note, however, that we did not assess actual dietary intake during our study, and therefore cannot prove that differences in dietary intake were responsible for differences in weight change between Trial and Program participants. The analysis that we have presented is intended to suggest potential avenues of research or food for thought. We are aware of its limitations, which include a small sample size, potential unmeasured differences between Program and Trial participants and, as noted above, no information on the actual dietary intake of either Program or Trial participants. Nonetheless, our examination of the weight loss achieved by Program participants suggests that a 24-week diet and exercise program has the potential to achieve more weight loss than suggested by our original clinical trial (4). Although a 2% between-group difference in weight change may seem trivial, we reiterate that among overweight adults with type 2 diabetes, weight reduction of as little as 5% may result in improved blood pressure, lipid profile and glycemic control (1,2): to eventually achieve such a 5% weight reduction, a 2% reduction is arguably of importance. There is a possibility that incorporation of a system of incentives or financial investment may improve adherence to such an intervention. There is also a possibility that a Montignacstyle strategy may facilitate weight loss, as suggested by other studies examining low-carbohydrate approaches. Our analysis cannot prove or disprove these possibilities, but we suggest that these issues should be examined in the context of developing effective dietary and activity programs targeting overweight adults with type 2 diabetes. ACKNOWLEDGEMENTS This research was supported by grants from the Canadian Institutes of Health Research Institute of Nutrition, Metabolism, and Diabetes and from the Research Institute of the McGill University Health Centre. One Touch Ultra glucometers and test strips were generously provided by Lifescan. Funding agencies and suppliers of material had no role in the design, conduct, analysis or reporting of this study. Mr. Hacene Nedjar provided invaluable assistance with statistical analyses. During the writing of this paper, GK was an endocrinology fellow at McGill University and the McGill University Health Centre. ER holds an investigator award from the Fonds de Recherche en Santé du Quebec and KD holds a New Investigator Award from the Canadian Institutes of Health Research. AUTHOR DISCLOSURES No dualities of interest declared. AUTHOR CONTRIBUTIONS The study protocol was designed by KD and executed by GK under KD s supervision. 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