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Original Investigation
January 17, 2017

Association Between Diabetes and Cause-Specific Mortality in Rural and Urban Areas of China

Author Affiliations
  • 1Clinical Trial Service Unit and Epidemiological Studies Unit, Nuffield Department of Population Health, University of Oxford, Oxford, England
  • 2Medical Research Council Population Health Research Unit, University of Oxford, Oxford, England
  • 3Chinese Academy of Medical Sciences, Beijing, China
  • 4Qingdao Center for Disease Control and Prevention, Qingdao, China
  • 5Henan Provincial Center for Disease Control and Prevention, Henan, China
  • 6National Center for Food Safety Risk Assessment, Beijing, China
  • 7School of Public Health, Peking University, Beijing, China
JAMA. 2017;317(3):280-289. doi:10.1001/jama.2016.19720
Key Points

Question  What is the excess mortality risk associated with diabetes in rural and urban areas of China?

Findings  In this 7-year nationwide prospective study of 512 869 adults, diabetes was more common in urban than rural areas (8.1% vs 4.1%, respectively), and individuals with diabetes had significantly increased risk of mortality from all causes and from a range of cardiovascular and noncardiovascular diseases.

Meaning  In China, diabetes is more common in urban than rural areas, and is associated with increased mortality. With an increasing adult population and rising prevalence of diabetes among young adults, the burden of diabetes-associated mortality will increase further.

Abstract

Importance  In China, diabetes prevalence has increased substantially in recent decades, but there are no reliable estimates of the excess mortality currently associated with diabetes.

Objectives  To assess the proportional excess mortality associated with diabetes and estimate the diabetes-related absolute excess mortality in rural and urban areas of China.

Design, Setting, and Participants  A 7-year nationwide prospective study of 512 869 adults aged 30 to 79 years from 10 (5 rural and 5 urban) regions in China, who were recruited between June 2004 and July 2008 and were followed up until January 2014.

Exposures  Diabetes (previously diagnosed or detected by screening) recorded at baseline.

Main Outcomes and Measures  All-cause and cause-specific mortality, collected through established death registries. Cox regression was used to estimate adjusted mortality rate ratio (RR) comparing individuals with diabetes vs those without diabetes at baseline.

Results  Among the 512 869 participants, the mean (SD) age was 51.5 (10.7) years, 59% (n = 302 618) were women, and 5.9% (n = 30 280) had diabetes (4.1% in rural areas, 8.1% in urban areas, 5.8% of men, 6.1% of women, 3.1% had been previously diagnosed, and 2.8% were detected by screening). During 3.64 million person-years of follow-up, there were 24 909 deaths, including 3384 among individuals with diabetes. Compared with adults without diabetes, individuals with diabetes had a significantly increased risk of all-cause mortality (1373 vs 646 deaths per 100 000; adjusted RR, 2.00 [95% CI, 1.93-2.08]), which was higher in rural areas than in urban areas (rural RR, 2.17 [95% CI, 2.07-2.29]; urban RR, 1.83 [95% CI, 1.73-1.94]). Presence of diabetes was associated with increased mortality from ischemic heart disease (3287 deaths; RR, 2.40 [95% CI, 2.19-2.63]), stroke (4444 deaths; RR, 1.98 [95% CI, 1.81-2.17]), chronic liver disease (481 deaths; RR, 2.32 [95% CI, 1.76-3.06]), infections (425 deaths; RR, 2.29 [95% CI, 1.76-2.99]), and cancer of the liver (1325 deaths; RR, 1.54 [95% CI, 1.28-1.86]), pancreas (357 deaths; RR, 1.84 [95% CI, 1.35-2.51]), female breast (217 deaths; RR, 1.84 [95% CI, 1.24-2.74]), and female reproductive system (210 deaths; RR, 1.81 [95% CI, 1.20-2.74]). For chronic kidney disease (365 deaths), the RR was higher in rural areas (18.69 [95% CI, 14.22-24.57]) than in urban areas (6.83 [95% CI, 4.73-9.88]). Among those with diabetes, 10% of all deaths (16% rural; 4% urban) were due to definite or probable diabetic ketoacidosis or coma (408 deaths).

Conclusions and Relevance  Among adults in China, diabetes was associated with increased mortality from a range of cardiovascular and noncardiovascular diseases. Although diabetes was more common in urban areas, it was associated with greater excess mortality in rural areas.

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