Ronald Sigal, MD, MPH, FRCPC

rsigal@ohri.ca


Affiliate Investigator, Clinical Epidemiology, Ottawa Hospital Research Institute

Associate Professor, Department of Medicine, University of Ottawa

Adjunct Professor, School of Human Kinetics, University of Ottawa

Staff Physician, Division of Endocrinology, Ottawa Hospital

Research Interests

Physical Activity Interventions in Diabetes Mellitus
Cardiovascular Disease in Diabetes Mellitus

Major Research Activities

Dr. Sigal's research is focused primarily in two areas, which overlap to some extent
1. Exercise interventions in diabetes mellitus
2. Primary and secondary prevention of cardiovascular disease in type 2 diabetes mellitus

1. EXERCISE AS AN INTERVENTION IN TYPE 2 DIABETES MELLITUS

Exercise has long believed to be beneficial for people with type 2 diabetes mellitus, but until recently there has been little in the way of strong evidence to support this belief. Our research group is carrying out clinical trials and systematic reviews in this area.

In a large clinical trial funded by Canadian Institutes of Health Research and the Canadian Diabetes Association, type 2 diabetic individuals are randomized for 6 months to 4 arms: aerobic exercise, resistance exercise, both combined, or waiting-list control. Metabolic control, body composition, resting and exercise-induced energy expenditure, heart disease risk factors and quality of life are measured at baseline, during and after the intervention. Subjects are reexamined 6 months after the intervention later to assess the durability of any benefits from the exercise program. The primary study outcome is blood glucose control, as measured by hemoglobin A1c at the end of the 6-month intervention period. A variety of substudies are under way as well.

Dr. Sigal is co-investigator on a clinical trial funded by National Cancer Institute of Canada examining the effects of different exercise modalities on quality of life in men with advanced prostate cancer. He is co-investigator on studies examining exercise-related behaviour, motivation and propensity to change, funded by the Canadian Diabetes Association and the Alberta Heritage Foundation for Medical Research.

Dr. Sigal's research group is the first to have carried out meta-analyses in the area of exercise and type 2 diabetes. The first of these was published in JAMA in September 2001, and others are under review or in progress. In 2002-2003, Dr. Sigal is taking the lead in revision of exercise clinical guidelines for both the Canadian Diabetes Association and the American Diabetes Association.

2. PRIMARY AND SECONDARY PREVENTION OF CARDIOVASCULAR DISEASE IN DIABETES

Diabetes mellitus is among the most potent risk factors for cardiovascular disease (CVD), and 60- 75% of people with diabetes die of CVD. Unlike smoking, hypertension and hypercholesterolemia, the prevalence of diabetes is rising dramatically. Moreover the CVD mortality rate in people with diabetes has declined little since the 1970s while that for nondiabetics declined more than 30%.

Dr Sigal is Ottawa Clinical Centre Principal Investigator for the NIH-funded clinical trial, Action to Control Cardiovascular Risk in Diabetes (ACCORD). The ACCORD study examines, in a factorial design, the effects on cardiovascular morbidity and mortality of very tight control of blood sugar, blood pressure and lipids. He is on the ACCORD trial committees in charge of lifestyle and background therapy, and medical outcomes assessment. Dr. Sigal is co-Investigator and member of the Steering Committee for the Heart and Stroke Foundation funded STREAM (Stent Restenosis and Metabolism) study. In this 4-city randomized trial, intensive glycemic control is being evaluated as an intervention to reduce intimal hyperplasia after angioplasty. He is also co-Investigator in the CIHR-funded multicentre POISE (PeriOperative Ischemic Evaluation) trial of beta-blockers to reduce cardiovascular risk in noncardiac surgery (CIHR-funded Clinical Trial).

Dr. Sigal is Ottawa Clinical Centre co-PI in the multicentre CIHR-funded clinical trial, "DREAM", in which people with impaired glucose tolerance are randomized in a factorial design to receive ramipril or ramipril placebo, and rosiglitazone or rosiglitazone placebo, with development of diabetes as the primary study outcome.

Dr. Sigal is responsible for a continuously-updated evidence-based review for the joint British Medical Association/American College of Physicians publication, "Clinical Evidence". He is also a member of the Canadian Diabetes Association Expert Committee."

Personnel Awards

1999-2004 Medical Research Council Research Scholarship

1995-96 Juvenile Diabetes Foundation International Post-doctoral Fellowship

1992-95 Canadian Diabetes Association Post-doctoral fellowship

Grants

Canadian Institutes of Health Research: Resistance Exercise as an Intervention in Type 2 Diabetes Mellitus 2001-2005. Principal Investigator

Canadian Institutes of Health Research: DREAM Study (Diabetes Reduction Approaches with ramapril and rosiglitazone Medications) 2001-2006 (Ottawa Centre Co-PI)

National Institutes of Health: Action to Control Cardiovascular Risks in Diabetes (ACCORD) Trial. 2000-2009 (Ottawa Clinical Centre PI)

National Cancer Institute of Canada: Exercise in men receiving radiation therapy for prostate cancer: effects on fatigue, toxicity of radiotherapy, body composition, muscular fitness, cardiorespiratory fitness and quality of life 2002-2005. Co-Investigator

Canadian Institutes of Health Research - Clinical Trials: PeriOperative ISchemic Evaluation Study 2001-2004 Co-Investigator

Canadian Institutes of Health Research - Clinical Trials: Folic acid deficiency in second trimester and adverse pregnancy outcomes 2002-2005 Co-Investigator

NSERC: Human Thermoregulation 2002-2003. Co-Investigator

Heart and Stroke Foundation of Ontario: Glycemic Control and In-Stent Restenosis 2001-2004 Local Co-investigator

Canadian Diabetes Association (Applied Research Grants): Exercise behaviour of community adults with Type 1 and Type 2 diabetes: The determinants of exercise behaviour change 2001-2003. Co-Investigator

Alberta Heritage Foundation for Medical Research: Exercise behaviour of community adults with Type 1 and Type 2 diabetes: A prospective examination of exercise determinants in a large population-based sample 2001-2003. Co-Investigator

Canadian Diabetes Association (The Lillian Hollefriend Grant): Modality of Exercise in Type 2 Diabetes: Effects on Metabolic Control, Lipids, Adipose Tissue Distribution and Quality of Life 1999-2001. Principal Investigator

Physician Services Incorporated (PSI) Foundation: Exercise as an Intervention for Early Diabetic Kidney Disease: A randomized, Controlled Trial 1998-2000. Principal Investigator

Major Committees

Chair, Canadian Diabetes Association Exercise Guidelines Committee
Member, Canadian Diabetes Association Task Force on Lipid-lowering Agents
Chair, Canadian Diabetes Association Task Force on Anti-Obesity Drugs
Member/Internal Reviewer, Canadian Diabetes Association National Grants Committee 1999-2001

Selected publications

Sigal RJ, Kenny G. Exercise in Diabetes Mellitus. In: Pickup JC and Williams G, Textbook of Diabetes. Oxford:Blackwell Scientific, 2002 in press.

Boulé, N, Haddad, E., Kenny, G., Wells, G.A., Sigal, R.J. Effects of Exercise on HbA1c and Body Mass in Type 2 Diabetes Mellitus: A Systematic Review. JAMA 2001 Sep;286(10):1218-1227.

Sigal RJ, Malcolm J. Diabetes and Cardiovascular Disease. In Clinical Evidence, Issue 5, London, BMJ Group, 2001;5:376-396. (I update this evidence-based literature review every 6 months; I wrote the corresponding chapters in Issues 1 through 4 and this chapter for issue 5).

Boulé NG, Haddad E, Kenny G, Sigal R. Exercise for type 2 diabetes mellitus (Protocol for a Cochrane Review). In: The Cochrane Library, Issue 1, 2001.

Sigal RJ, Fisher S, Halter JB, Vranic M, Marliss EB. Glucoregulation during and after intense exercise: a-adrenergic mechanisms. Metabolism. 2000 Mar;49(3):386-94.

Hu FB, Sigal RJ, Rich-Edwards JW, Colditz GA, Solomon CG, Willett WC, Speizer FE, Manson JE. Walking as Compared to Vigorous Exercise and Risk of Type 2 Diabetes in Women: A Prospective Study. JAMA 1999; 282:1433-1439.

Sigal RJ, Fisher SJ, Halter JB, Vranic M, Marliss EB. Glucoregulation during and after intense exercise: effects of b-adrenergic blockade in subjects with type 1 diabetes mellitus. J Clin Endocrinol Metab 1999;84: 3961-3971.

Manzon A, Fisher SJ, Morais JA, Lipscombe L, Guimond MC, Nessim S, Sigal RJ, Halter JB, Vranic M, Marliss EB. Glucose infusion does not prevent the endogenous glucose production response and increases glucose uptake during intense exercise. J Appl Physiol 1998;85(2):511-24.

Manzon A, Fisher SJ, Morais JA, Lipscombe L, Guimond MC, Nessim S, Sigal RJ, Halter JB, Vranic M, Marliss EB. Glucose infusion does not prevent the endogenous glucose production response and increases glucose uptake during intense exercise. J Appl Physiol 1998;85(2):511-24.

Sigal RJ, El-Hashimy M, Martin BC, Soeldner JS, Krolewski AS, Warram JH. Acute postchallenge hyperinsulinemia predicts weight gain: a prospective study. Diabetes 1997;46:1025-1029.

Sigal RJ, Fisher S, Vranic M, Halter JB, and Marliss EB. The roles of catecholamines in glucoregulation in intense exercise as defined by the islet cell clamp technique. Diabetes 1996;45(2):148-156.

Sigal RJ, Doria A, Warram JH, Krolewski AS. Codon 972 polymorphism in the insulin-receptor substrate-1 (IRS-1) gene, obesity and risk of noninsulin-dependent diabetes mellitus. J Clin Endocrinol Metab 1996;81:1657-59.

Warram JH, Sigal RJ, Martin BC, Krolewski AS, Soeldner JS. Natural history of impaired glucose tolerance: follow-up at Joslin Clinic. Diabetic Med 1996;13(Suppl.6):S40-S45.