Obesity and physical inactivity are well-known risk factors for the development of type 2 diabetes.1 The American Diabetes Association (ADA), the American Academy of Clinical Endocrinologists, and the U.S. Preventive Services Task Force recommend intensive lifestyle interventions for people with type 2 diabetes.2
The current guidelines by the ADA recommend diet, physical activity, and behavioral therapy to achieve a 5% weight loss for overweight (body mass index (BMI) >25-29.9kg/m2) and obese (BMI >30kg/m2) individuals with type 2 diabetes. Adults with diabetes are advised to engage in aerobic activity of moderate intensity for at least 150 min/week over at least three days/week with no more than two consecutive days of inactivity. In conjunction to physical activity, individualized dietary changes are recommended to promote greater intake of foods rich in fiber and low in glycemic load, while creating a sufficient energy deficit (500 – 700 kcal/day) to allow healthy weight loss. These recommendations are based on multiple studies on lifestyle intervention programs showing that weight loss, healthier eating, and increased physical activity have a positive impact on diabetes onset and progression.2-4
The Diabetes Prevention Program, a multicenter randomized controlled trial comprised of randomized participants (n=3150) that were at high risk of developing diabetes due to being an adult and having BMIs above recommended levels. The participants were placed into three groups: intensive lifestyle intervention targeting diet and exercise, and two medication groups (metformin or placebo) with standard diet and exercise recommendations.3 The study concluded that weight loss achieved through intensive lifestyle intervention delayed the onset of type 2 diabetes and reduced overall diabetes incidence by 34% (95% confidence interval [CI] [24 – 42]) over 10 years and 27% (hazard ratio 0.73, 95% CI [0.65 – 0.83], p<0.0001) over 15 years when compared to the placebo group. Metformin intervention reduced overall diabetes incidence by 18% (95% CI [7-28]) over 15 years when compared to the placebo group.3,5
The Look AHEAD (Action for Health in Diabetes), another multicenter randomized controlled trial, randomized people with overweight or obesity and type 2 diabetes (n=5145) to intensive lifestyle intervention (ILI) or diabetes support and education (DSE) group.4 The ILI group received comprehensive behavioral weight loss counseling for eight years whereas the DSE group received only periodic group education that discussed diet, physical activity, and social support. Mean weight loss from initial weight at year eight was 4.7 ± 0.2% in the ILI group and 2.1 ± 0.2% in the DSE group (p<0.001). More participants in the ILI group lost ≥5% of initial weight than those in the DSE group (50.3% and 35.7%, respectively, p<0.001). An ancillary observational study reported that weight loss of >5% of initial body weight through intensive lifestyle intervention led to improved glycemic control and reduced need for glucose-lowering medications.6
In addition to obesity and physical inactivity, smoking is associated with the development of type 2 diabetes.7 A meta-analysis of 25 prospective cohort studies (n=1.2 million) found that current smokers have a greater risk of developing type 2 diabetes when compared to nonsmokers (pooled adjusted risk ratio 1.44, 95% CI [1.3 – 1.6]).8ADA guidelines recommend that people with diabetes be advised not to use cigarettes and other tobacco products.1,7A meta-analysis found that non-smokers with diabetes had a lower level of HbA1c −0.61 (95% CI −0.88 to −0.33; p<0.001), a higher level of HDL cholesterol 0.12 (95% CI 0.08 to 0.15; p < 0.001) and lower level of LDL cholesterol −0.11 (95% CI −0.21 to −0.01; p = 0.03), compared to smokers.9
References
- Standards of Medical Care in Diabetes-2022 Abridged for Primary Care Providers. Clin Diabetes. Jan 2022;40(1):10-38. doi:10.2337/cd22-as01
- Rosenfeld RM, Kelly JH, Agarwal M, et al. Dietary Interventions to Treat Type 2 Diabetes in Adults with a Goal of Remission: An Expert Consensus Statement from the American College of Lifestyle Medicine. Am J Lifestyle Med. May-Jun 2022;16(3):342-362. doi:10.1177/15598276221087624
- Knowler WC, Fowler SE, Hamman RF, et al. 10-year follow-up of diabetes incidence and weight loss in the Diabetes Prevention Program Outcomes Study. Lancet. Nov 14 2009;374(9702):1677-86. doi:10.1016/s0140-6736(09)61457-4
- Eight-year weight losses with an intensive lifestyle intervention: the look AHEAD study. Obesity (Silver Spring). Jan 2014;22(1):5-13. doi:10.1002/oby.20662
- Long-term effects of lifestyle intervention or metformin on diabetes development and microvascular complications over 15-year follow-up: the Diabetes Prevention Program Outcomes Study. Lancet Diabetes Endocrinol. Nov 2015;3(11):866-75. doi:10.1016/s2213-8587(15)00291-0
- Gregg EW, Chen H, Wagenknecht LE, et al. Association of an intensive lifestyle intervention with remission of type 2 diabetes. Jama. Dec 19 2012;308(23):2489-96. doi:10.1001/jama.2012.67929
- 5. Lifestyle Management: Standards of Medical Care in Diabetes-2019. Diabetes Care. Jan 2019;42(Suppl 1):S46-s60. doi:10.2337/dc19-S005
- Willi C, Bodenmann P, Ghali WA, Faris PD, Cornuz J. Active smoking and the risk of type 2 diabetes: a systematic review and meta-analysis. Jama. Dec 12 2007;298(22):2654-64. doi:10.1001/jama.298.22.2654
- Kar D, Gillies C, Zaccardi F, et al. Relationship of cardiometabolic parameters in non-smokers, current smokers, and quitters in diabetes: a systematic review and meta-analysis. Cardiovascular Diabetology. 2016/11/24 2016;15(1):158. doi:10.1186/s12933-016-0475-5
