Combination of Five Lifestyle Factors Reduces Diabetes Risk

Diabetes, a disease in which blood glucose (sugar) levels are too high, affects an estimated 25.8 million Americans of all ages—more than 8 percent of the population. It’s a major cause of heart disease and stroke and is the seventh leading cause of death in the United States. Type 2 diabetes is the most common form and accounts for 90–95 percent of all diagnosed cases in adults. Improvements in individual lifestyle factors, such as not smoking or maintaining a healthy body weight, have been known to prevent or delay the onset of type 2 diabetes. A new analysis shows that a combination of five healthy lifestyle factors is associated with a substantially lower risk of developing type 2 diabetes.

There are two main types of diabetes: type 1 and type 2. In type 1 diabetes (formerly called juvenile diabetes or insulin-dependent diabetes) the body doesn’t make enough insulin, which causes blood glucose levels to rise. In type 2 diabetes (formerly called adult-onset or noninsulin dependent diabetes) the cells in the muscles, liver, and fat don’t use insulin properly. Over time, high blood glucose damages nerves and blood vessels, leading to complications such as heart disease, stroke, blindness, kidney disease, nerve problems, gum infections, and amputation. It is not surprising that medical expenses for people with diabetes are more than 2 times higher than for people without diabetes.

What was the study?

"Lifestyle factors and risk for new-onset diabetes: A population-based cohort study," was led by Jared Reis, Ph.D., of the National Heart, Lung, and Blood Institute (NHLBI). The study was published in the Annals of Internal Medicine, September 6, 2011.

The study involved 114,996 men and 92,483 women who were part of the National Institutes of Health (NIH)-AARP Diet and Health Study. The individuals were aged 50–71 years at the start of the study (from 1995 to 1996) and did not have heart disease, cancer, or diabetes at the time.

The participants were asked about five lifestyle factors at the start of the study:

• Diet and alcohol use. Participants completed a food-frequency questionnaire on the consumption and usual portion size of 124 food items and alcohol use during the previous year. The questionnaire was validated by administering two nonconsecutive 24-hour dietary recalls to more than 2,000 randomly chosen participants.
• A low-risk dietary pattern was determined based on the glycemic index, ratio of polyunsaturated to saturated fat, and fiber and trans fat levels of the foods consumed.
• Low-risk alcohol consumption was defined as moderate consumption of between 5 grams per day (g/day) and 29.9 g/day for men or 14.9 g/day for women, consistent with current U.S. guidelines for alcohol intake. This corresponds to no more than two drinks per day for men and one drink per day for women.
• Physical activity. Participants reported on how often they engaged in physical activity for at least 20 minutes that resulted in increased breathing or heart rate, or produced perspiration (never, rarely, 1–3 times a month, 1–2 times a week, 3–4 times a week, or 5 or more times a week).  
• Low risk was defined as participation in at least 20 minutes of physical activity 3 or more times per week.
• Smoking. To identify ever- and never-smokers, participants were asked whether they had ever smoked 100 or more cigarettes in their lifetime. Ever-smokers were asked whether they currently smoked or if (and when) they had stopped smoking, and how many cigarettes they smoked per day.
• Low risk was defined as never smoking or having quit smoking for 10 or more years.
• Body mass index (BMI). BMI was calculated from the participants’ self-reported weight and height.
• Low-risk weight was defined as a BMI of 18.5–24.9 kilograms/meters2 (kg/m2), which is considered normal weight.
• New-onset diabetes was determined by asking participants whether a physician told them that they had diabetes. Individuals were asked this question at baseline (1995–1996) and at followup (2004–2006). Although the questionnaire did not differentiate between type 1 and type 2 diabetes, it was assumed that almost all cases were type 2 diabetes.
• The associations between lifestyle factors reported at the beginning of the study and self-reported diabetes onset anytime during the ensuing 11-year period were analyzed.

What did the study find?

• During 11 years of followup, 9.6 percent of the men and 7.5 percent of the women developed diabetes.
• There was a strong inverse dose-response relationship between the low-risk healthy lifestyle factors and developing diabetes. Each healthy lifestyle factor that the participants incorporated within their lives was associated with a 31 percent lower risk for diabetes for men and a 39 percent lower risk for women.
• Men with all five healthy lifestyle factors had a 72 percent lower risk for developing diabetes, and women had an 84 percent lower risk.
• Of the five lifestyle factors, BMI showed the strongest association with developing diabetes.
• Men and women who had never smoked, or who had successfully quit smoking 10 or more years before the baseline, had a 24 percent and 16 percent lower risk of diabetes, respectively.
• Participants who were overweight or obese at the start of the study but otherwise engaged in low-risk lifestyle behaviors had a lower risk for developing diabetes.
• The relationships between the lifestyle factors and risk of developing diabetes were similar for those with and without a family history of diabetes.
• Approximately 30 percent of both men and women had two lifestyle factors in the low-risk category. Participants with more factors in the low-risk category were slightly older and more likely to be White or Hispanic, college educated, or married; have a lower total energy intake; and consume more fruits and vegetables.
• Limitations of this study include:
• The healthy lifestyle risk factors were only determined at baseline and may have changed during the 11-year followup period.
• The lifestyle factors were self-reported, as was the assessment of diabetes.

What are the take-home messages?

• Individuals aged 50–71 years with a low-risk lifestyle profile have a dramatically lower risk for developing diabetes. The low-risk lifestyle factors include:
• Maintaining an optimal body weight (a BMI in the normal range)
• Engaging in regular physical activity
• Consuming a healthful diet
• Keeping alcohol use to no more than one drink per day for women and two drinks per day for men
• Not smoking or being smoke-free for at least 10 years
• Overweight or obese individuals who adopt other low-risk lifestyle behaviors may lower their risk for diabetes.
• Individuals with a family history of diabetes may prevent or at least delay the development of diabetes by engaging in a healthy lifestyle.
• Middle-aged individuals can significantly lower their diabetes risk by improving even one lifestyle factor, since each of the five lifestyle factors is independently associated with risk for diabetes.

Health care professionals can help individuals lower their risk of developing diabetes by encouraging them to focus on a single lifestyle change at a time.  For each additional healthy lifestyle behavior that an individual adopts, he or she may continue to significantly lower his or her risk of diabetes in an additive fashion.

Popular NHLBI Resources

Practical, evidence-based strategies and tools based on research supported by the National Heart, Lung, and Blood Institute (NHLBI) are available for clinicians, patients, and the general public. Examples include:

• NHLBI Diseases and Conditions Index (DCI): Diabetic Heart Disease, Overweight and Obesity, Physical Activity and Your Heart, Smoking and Your Heart
• Aim for a Healthy Weight Provider Kit
• Aim for a Healthy Weight: 3 Steps to Initiate Discussion About Weight Management With Your Patients
• Aim for a Healthy Weight Patient Booklet
• Your Heart, Your Life: A Lay Health Educator’s Manual for the Hispanic Community
• On the Move to Better Heart Health for African Americans
• Your Guide to Physical Activity and Your Heart

Where can I learn more?

• Reis, J.P., Loria, C.M., Sorlie, P.D., Park, Y., Hollenbeck, A., Schatzkin, A. (2011). Lifestyle factors and risk for new-onset diabetes: A population-based cohort study. Annals of Internal Medicine, 155(5), 292–299.
• NIH-AARP Diet and Health Study
• NIH Media Availability: Combination of five lifestyle factors linked to lower diabetes risk (news release)  

Additional information on the study

October 2011