Obesity and Type 2 Diabetes Mellitus

      It is now widely accepted that the obesity epidemic continues to be the principal driver for the rising global prevalence of type 2 diabetes mellitus (
      • Lau D.C.W.
      New insights in the prevention and early management of type 2 diabetes.
      ). With the unabated increase in the prevalence of obesity, every year the World Health Organization (WHO) has to increase the projected global figures of the number of people with diabetes for 2030. The latest figure of 532 million people who will develop diabetes by 2030 will likely be revised (
      • Lau D.C.W.
      A world with fewer people with diabetes and noncommunicable diseases.
      ). Canada's obesity prevalence rate of 25.5% ranks fourth among the OECD countries, behind the United States (34.3%), Mexico (30%) and New Zealand (26.5%), and ahead of the United Kingdom (24%) (
      • Lau D.C.W.
      New insights in the prevention and early management of type 2 diabetes.
      ). Sadly, the latest figures on adult Canadians who are overweight and obese based on self-reported body mass indices show no reversal in its prevalence and trends. According to data released by Statistics Canada earlier this year (based on self-reported body mass indices), 52% of Canadians age 18 years and over are overweight or obese (

      Statistics Canada. Obesity. 2013. (available online at http://www.statcan.gc.ca/search-recherche/bb/info/obesity-obesite-eng.htm). Accessed February 12, 2013.

      ). The number of overweight/obese Canadians continue to rise over the past 5 years, from 12.1 million in 2007 to 13.2 million in 2011 (8.8% increase) (

      Statistics Canada. Obesity. 2013. (available online at http://www.statcan.gc.ca/search-recherche/bb/info/obesity-obesite-eng.htm). Accessed February 12, 2013.

      ). More than 60% of men age 35 years and older are overweight or obese and there has been a 20% increase since 2007 (

      Statistics Canada. Obesity. 2013. (available online at http://www.statcan.gc.ca/search-recherche/bb/info/obesity-obesite-eng.htm). Accessed February 12, 2013.

      ). Over the last 2 decades, the average self-reported body mass index (BMI) of adult Canadians has increased by approximately 3 kg/m2, from 22.3 to 25.3 kg/m2, which is in the overweight range (
      • Gotay C.C.
      • Katzmarzyk P.T.
      • Janssen I.
      • et al.
      Updating the Canadian obesity maps: an epidemic in progress.
      ). Obesity rates have roughly doubled across all age groups over the past 3 decades, and we are less physically fit (
      )! Importantly, 20% of Canadian youths are overweight or obese, and the number continues to rise, notably in the Maritime provinces (

      Statistics Canada. Obesity. 2013. (available online at http://www.statcan.gc.ca/search-recherche/bb/info/obesity-obesite-eng.htm). Accessed February 12, 2013.

      ).
      This issue of the Canadian Journal of Diabetes, published on the occasion of the 3rd Canadian Obesity Summit (Vancouver, May 1–4, 2013), features several articles on the state of obesity and diabetes in Canada. It also includes abstracts submitted to the Canadian Obesity Summit, the largest biennial conference that brings interested researchers, clinicians, health professionals and policy makers together from across Canada.
      As pointed out by Ian Janssen, there are presently approximately 7 million obese adults and 600,000 obese school-aged children in Canada, with obesity accounting for approximately 61% to 74% of type 2 diabetes cases (
      • Janssen I.
      The public health burden of obesity in Canada.
      ). The estimated direct and indirect costs of obesity for the Canadian healthcare system exceed $7 billion per year. In a research analysis commissioned by the Canadian Diabetes Association (CDA) in 2009, the estimated cost of diabetes, which takes into consideration the continuing rise in obesity-related type 2 diabetes, projects that it will rise from $6.3 billion in 2000 to 16.9 billion by 2020 (
      • Doucet G.
      • Beatty M.
      The cost of diabetes in Canada: the economic Tsunami.
      ). Taken together, the continuing “diabesity” epidemic in Canada poses a very serious health and economic burden.
      Although having a positive family history of diabetes or obesity are well-recognized as risk factors for the development of diabetes, whether the joint effect of a family history of diabetes as well as obesity might further augment diabetes risk is the subject of a study led by Ning et al (
      • Ning F.
      • Pang Z.
      • Laatikainen T.
      • et al.
      Joint effect of family history of diabetes with obesity on prevalence of type 2 diabetes among the Chinese and Finnish men and women.
      ). These investigators also examined whether there were ethnic differences between 2 population-based surveys in China and Finland, both of which were included in the DECODA/DECODE (Diabetes Epidemiology: Collaborative Analysis Of Diagnostic cRiteria in Asia/Europe) collaboration.
      The joint PHAC-CIHI report entitled “Obesity in Canada” suggested that improving the health behaviours of Canadians by increasing low impact physical activity 15 minutes daily, along with more vegetable and fruit consumption, could reduce the equivalent of over 1 million cases of obesity (
      ). In addressing the obesogenic environment, the report outlined 3 broad strategies to combat the pandemic of obesity in Canada. The first is aimed at health services and interventions that target individuals. The second is community-level interventions that directly influence individual and group health behaviours, and thirdly, develop public policies that target broad social and environmental determinants. Clearly a comprehensive, multifaceted approach combining individual, community and population levels will be most effective to reduce the prevalence of obesity and its attendant health complications.
      Combating childhood obesity remains a considerable and unsolved challenge and calls for novel approaches to delivery and intervention. Jagova and colleagues report on the process evaluation of a web-based child obesity management program called Living Green, Healthy and Thrifty (LiGHT): Combining Health Promotion with Ecology and Economy (
      • Jogova M.
      • Campbell A.C.
      • Warbutton D.W.
      • et al.
      Process evaluation of the Living Green, Healthy and Thrifty (LiGHT) web-based child obesity management program: combining health promotion with ecology and economy.
      ). In their analysis of participant responses, convenience, accessibility and practical aspects of the program were appreciated although the lack of visual appeal and overabundance of text was identified as a challenge that may need to be further addressed.
      In addressing the third strategy outlined in the joint PHAC-CIHI report, Susan Buhler and colleagues present a cogent case of sugar-sweetened beverage taxation as one example of building a multipronged comprehensive strategy for obesity prevention in children and youths (
      • Buhler S.
      • Raine K.
      • Arango M.
      • et al.
      Building a strategy for obesity prevention one piece at a time: the case of sugar-sweetened beverage taxation.
      ).
      Epidemiological studies suggest that higher BMI, central body fat with higher waist circumferences are often associated with adults and children who are habitual short sleepers (
      • Chaput J.P.
      • Tremblay A.
      Insufficient sleep as a contributor to weight gain: an update.
      ). Poor sleep hygiene and sleep deprivation have become a prevalent problem in many societies where fast-paced lifestyle is the norm, and have been linked to increased insulin resistance and higher circulating cortisol levels, and increased risk for diabetes (
      • Zizi F.
      • Jean-Louis G.
      • Brown C.D.
      • et al.
      Sleep duration and the risk of diabetes mellitus: epidemiologic evidence and pathophysiologic insights.
      ). McNeil and colleagues reviewed the evidence that increased susceptibility to food stimuli, especially energy-dense, high-carbohydrate foods, may be related to inadequate sleep, which predisposes to central obesity and type 2 diabetes in susceptible individuals (
      • McNeil J.
      • Doucet É.
      • Chaput J.-P.
      Inadequate sleep as a contributor to obesity and type 2 diabetes.
      ).
      Excess body fat and notably abdominal adiposity greatly increase the risk for insulin resistance, type 2 diabetes in susceptible individuals, cardiovascular disease, musculoskeletal disease, cancers and all-cause mortality. The concept of ectopic fat has gained much attention to proffer a more comprehensive explanation for the adverse impact of excess adiposity on glucose and fat metabolism, leading to the constellation of features often referred to as cardiometabolic risk. André Carpentier draws our attention to the role of ectopic fat deposition in skeletal muscles, liver, heart, which overexposes these tissues to fatty acids, resulting in increased de novo lipogenesis, impaired fatty acid oxidation and increased fatty acid flux to these organs (
      • Carpentier A.C.
      The 2012 CDA-CIHR INMD Young Investigator Award Lecture: dysfunction of adipose tissues and the mechanisms of ectopic fat deposition in type 2 diabetes.
      ). In addition, brown adipose tissue depots appear to be less metabolically active in individuals with type 2 diabetes, thereby further impairing energy homeostasis.
      Réjeanne Gougeon reminds us that insulin resistance also affects protein metabolism, with a propensity for greater loss of lean tissue and muscle strength (
      • Gougeon R.
      Insulin resistance of protein metabolism in type 2 diabetes and impact on dietary needs.
      ). Thus, caloric restriction should primarily come from reductions in carbohydrate and fat intake whereas protein intake should be maintained or even increased to ensure conservation of lean body mass.
      Recent studies in humans have provided insights into why people who have lost weight have difficulty maintaining the weight loss and preventing weight regain partly because of hormonal and metabolic adaptation (
      • Sumithran P.
      • Prendergast L.A.
      • Delbridge E.
      • et al.
      Long-term persistence of hormonal adaptations to weight loss.
      ). Jennifer Reed and colleagues underscored in their review that not only does weight reduction lead to markedly reduced energy needs but also an augmented drive to eat, thereby making it difficult for individuals to maintain weight loss over time (
      • Reed J.
      • Chaput J.-P.
      • Tremblay A.
      • Doucet É.
      The maintenance of energy balance is compromised after weight loss.
      ). The authors concluded that the maintenance of energy balance is often compromised after weight loss.
      We now have compelling and irrefutable evidence that intensive lifestyle intervention as well as metformin, acarbose and orlistat, are highly effective in delaying or preventing the onset of type 2 diabetes (
      • Gillies C.L.
      • Abrams K.R.
      • Lambert P.C.
      • et al.
      Pharmacological and lifestyle interventions to prevent or delay type 2 diabetes in people with impaired glucose tolerance: systematic review and meta-analysis.
      ). Data from the US Diabetes Prevention Program concluded that each 1 kg weight loss is associated with a 16% relative risk reduction in the development of diabetes (
      Diabetes Prevention Program Research Group
      10-year follow-up of diabetes incidence and weight loss in the Diabetes Prevention Program Outcomes Study.
      ). A very modest 1.1% body weight loss per year for 4 years through lifestyle modification can delay diabetes by 4 years . Whether a modest weight loss of 1% to 5% is beneficial for people with diabetes is the subject of a review by Lau and Teoh in this issue (
      • Lau D.C.
      • Teoh H.
      Benefits of modest weight loss on the management of Type 2 diabetes mellitus.
      ). This review emphasizes that a modest but achievable weight loss of 5% to 10% can be a realistic goal for improving glycemic control in patients with type 2 diabetes.
      With respect to diabetes management, the DM-SCAN survey of over 5000 patients with type 2 diabetes from primary care practices across Canada reveals that 50% of patients are not at glycemic target, with glycated hemoglobin levels ≥0.7%. This study highlights persistent clinical inertia and treatment gap in the management of patients with type 2 diabetes by primary care practitioners (
      • Leiter L.A.
      • Berard L.
      • Bowering C.K.
      • et al.
      Type 2 diabetes mellitus management in Canada: is it improving?.
      ). Hopefully with the imminent release of the much-anticipated 2013 CDA clinical practice guidelines on the management and prevention of diabetes, it will provide an impetus to improve diabetes care in Canada.
      Although this collection of articles certainly provides a succinct overview of the many topics and issues relevant to obesity and diabetes in Canada, it is also evident that many challenges lie ahead. We have no doubt that reducing the burden of obesity and diabetes on Canadians will require the ongoing and close collaborations between the CDA, Canadian Obesity Network in partnership with many other relevant sectors and stakeholders.

      References

        • Lau D.C.W.
        New insights in the prevention and early management of type 2 diabetes.
        Can J Diabetes. 2011; 35: 239-241
        • Lau D.C.W.
        A world with fewer people with diabetes and noncommunicable diseases.
        Can J Diabetes. 2011; 35: 314-316
      1. Statistics Canada. Obesity. 2013. (available online at http://www.statcan.gc.ca/search-recherche/bb/info/obesity-obesite-eng.htm). Accessed February 12, 2013.

        • Gotay C.C.
        • Katzmarzyk P.T.
        • Janssen I.
        • et al.
        Updating the Canadian obesity maps: an epidemic in progress.
        Can J Public Health. 2013; 104: e64-e68
      2. Obesity in Canada. Canadian Institute for Health Information and Public Health Agency of Canada, Ottawa2011 (1–62)
        • Janssen I.
        The public health burden of obesity in Canada.
        Can J Diabetes. 2013; 37: 90-96
        • Doucet G.
        • Beatty M.
        The cost of diabetes in Canada: the economic Tsunami.
        Can J Diabetes. 2010; 34: 27-28
        • Ning F.
        • Pang Z.
        • Laatikainen T.
        • et al.
        Joint effect of family history of diabetes with obesity on prevalence of type 2 diabetes among the Chinese and Finnish men and women.
        Can J Diabetes. 2013; 37: 65-71
        • Jogova M.
        • Campbell A.C.
        • Warbutton D.W.
        • et al.
        Process evaluation of the Living Green, Healthy and Thrifty (LiGHT) web-based child obesity management program: combining health promotion with ecology and economy.
        Can J Diabetes. 2013; 37: 72-81
        • Buhler S.
        • Raine K.
        • Arango M.
        • et al.
        Building a strategy for obesity prevention one piece at a time: the case of sugar-sweetened beverage taxation.
        Can J Diabetes. 2013; 37: 97-102
        • Chaput J.P.
        • Tremblay A.
        Insufficient sleep as a contributor to weight gain: an update.
        Current Obes Rep. 2012; 1: 245-256
        • Zizi F.
        • Jean-Louis G.
        • Brown C.D.
        • et al.
        Sleep duration and the risk of diabetes mellitus: epidemiologic evidence and pathophysiologic insights.
        Curr Diabetes Rep. 2010; 10: 43-47
        • McNeil J.
        • Doucet É.
        • Chaput J.-P.
        Inadequate sleep as a contributor to obesity and type 2 diabetes.
        Can J Diabetes. 2013; 37: 103-108
        • Carpentier A.C.
        The 2012 CDA-CIHR INMD Young Investigator Award Lecture: dysfunction of adipose tissues and the mechanisms of ectopic fat deposition in type 2 diabetes.
        Can J Diabetes. 2013; 37: 109-114
        • Gougeon R.
        Insulin resistance of protein metabolism in type 2 diabetes and impact on dietary needs.
        Can J Diabetes. 2013; 37: 115-120
        • Sumithran P.
        • Prendergast L.A.
        • Delbridge E.
        • et al.
        Long-term persistence of hormonal adaptations to weight loss.
        N Engl J Med. 2011; 365: 1597-1604
        • Reed J.
        • Chaput J.-P.
        • Tremblay A.
        • Doucet É.
        The maintenance of energy balance is compromised after weight loss.
        Can J Diabetes. 2013; 37: 121-127
        • Gillies C.L.
        • Abrams K.R.
        • Lambert P.C.
        • et al.
        Pharmacological and lifestyle interventions to prevent or delay type 2 diabetes in people with impaired glucose tolerance: systematic review and meta-analysis.
        BMJ. 2007; 334: 299
        • Diabetes Prevention Program Research Group
        10-year follow-up of diabetes incidence and weight loss in the Diabetes Prevention Program Outcomes Study.
        Lancet. 2009; 374: 1677-1686
        • Lau D.C.
        • Teoh H.
        Benefits of modest weight loss on the management of Type 2 diabetes mellitus.
        Can J Diabetes. 2013; 37
        • Leiter L.A.
        • Berard L.
        • Bowering C.K.
        • et al.
        Type 2 diabetes mellitus management in Canada: is it improving?.
        Can J Diabetes. 2013; 37: 82-89