Impact of lifestyle-related factors on all-cause and cause-specific mortality in patients with type 2 diabetes: the Taichung Diabetes Study

OBJECTIVE

To examine whether combined lifestyle behaviors have an impact on all-cause and cause-specific mortality in patients aged 30–94 years with type 2 diabetes (T2DM).

RESEARCH DESIGN AND METHODS

Participants included 5,686 patients >30 years old with T2DM who were enrolled in a Diabetes Care Management Program at a medical center in central Taiwan before 2007. Lifestyle behaviors consisted of smoking, alcohol drinking, physical inactivity, and carbohydrate intake. The main outcomes were all-cause and cause-specific mortality. Cox proportional hazards models were used to examine the association between combined lifestyle behaviors and mortality.

RESULTS

The mortality rate among men was 24.10 per 1,000 person-years, and that among women was 17.25 per 1,000 person-years. After adjusting for the traditional risk factors, we found that combined lifestyle behavior was independently associated with all-cause mortality and mortality due to diabetes, cardiovascular disease, and cancer. Patients with three or more points were at a 3.50-fold greater risk of all-cause mortality (95% CI 2.06–5.96) and a 4.94-fold (1.62–15.06), 4.24-fold (1.20–14.95), and 1.31-fold (0.39–4.41) greater risk of diabetes-specific, CVD-specific, and cancer-specific mortality, respectively, compared with patients with zero points. Among these associations, the combined lifestyle behavior was not significantly associated with cancer mortality.

CONCLUSIONS

Combined lifestyle behavior is a strong predictor of all-cause and cause-specific mortality in patients with T2DM.Type 2 diabetes (T2DM) and its complications are leading causes of premature mortality, imposing a heavy burden at the individual and societal level (1,2). With the Westernization of diet behaviors, the prevalence of T2DM has increased dramatically in Taiwan. The National Nutrition Survey in Taiwan revealed that the prevalence of T2DM among men aged ≥65 years had increased dramatically: from 13.1 to 17.6 to 28.5% in 1993–1996, 2002, and 2005–2008, respectively (3). The International Diabetes Federation (2) proposed that the causes of the increase in diabetes prevalence were population aging and unhealthy lifestyle behaviors. The components of these unhealthy lifestyle behaviors included being physically inactive, smoking, alcohol drinking, and having an unhealthy diet (4–6).T2DM is also an important cause of microvascular and macrovascular diseases. Lifestyle modifications in conjunction with antidiabetes medications can prevent premature morbidity and mortality (5,7). However, for individuals with diabetes, the most difficult task is to strike a balance between the individual’s desires and compliance with behavior modification for disease management. It has been reported that individuals with diabetes who practice healthy lifestyle behaviors have better glycemic control (8) and that better glycemic control is associated with lower mortality (9). Although the effects of these individual or combined lifestyle behaviors on mortality have been well studied in general populations (10–18), little is known about the association between these lifestyle behaviors and mortality in patients with T2DM (5,19). Understanding the relationships of these modifiable predictors on mortality in patients with T2DM will have great clinical significance for diabetes care.The Taichung Diabetes Study is a population-based cohort study of ~6,000 middle-aged and older ethnic Chinese patients with T2DM who enrolled in the Diabetes Care Management Program (DCMP) of a medical center in Taiwan. The DCMP provides financial incentives for physicians to increase exhaustive follow-up visits, including annual self-care education and assessment by care managers and a clinical nutrition practitioner, annual eye examinations, and four annual laboratory tests. The DCMP provided a unique opportunity to quantify the overall impact of lifestyle factors, including smoking, alcohol drinking, regular exercise, and carbohydrate intake, on mortality. The purpose of this study was to fill this gap in knowledge by investigating the prospective associations among lifestyle factors and all-cause, diabetes-, cardiovascular disease (CVD)-, and cancer-specific mortality, independently of HbA_1c, and several baseline traditional factors, in a large cohort of ethnic Chinese patients with T2DM who were followed up for more than 4 years.