Study Finds Diabetes Associated with Premature Death from Cancer, Infectious Diseases

Diabetes mellitus is known to increase the risk of vascular diseases, but a new study found that diabetes is also associated with premature death from several forms of cancer, infectious diseases, external causes, intentional self-harm, and degenerative disorders. These latest findings were reported in the New England Journal of Medicine [2011;364(9):829-841]. While the association between diabetes and vascular diseases has been well documented, less is known about whether diabetes and hyperglycemia also increase the risk of death from cancer or other nonvascular diseases. In this study, researchers investigated the implications of diabetes further by compiling data from 97 different prospective studies to determine whether there were any independent associations between cause-specific death and a patient’s baseline diabetes status or fasting glucose levels. The study, which was conducted by the Emerging Risk Factors Collaboration, included data from 820,900 people with no known preexisting vascular disease at baseline. Each participant also had to have complete information available about age, sex, body mass index (BMI), smoking status, and diabetes status or fasting glucose level to be included. The data included information on 123,205 deaths over 12.3 million person-years at risk. The mean (±SD) age of participants at the baseline was 55±9 years. In addition, of the 715,061 participants who underwent an analysis of their diabetes status, 6% were determined to have diabetes at the time of enrollment. Most of the participants were enrolled in studies either in Europe or North America. When researchers were developing the analysis, they identified outcomes of the study as death from any cause, as well as deaths from cancer, vascular disease, and nonvascular conditions not attributed to cancer. Overall, researchers found that crude rates of death were higher in participants who had diabetes (29 per 1000 person-years among men and 23 per 1000 person-years among women) when compared with those participants without diabetes (12 per 1000 person-years among men and 7 per 1000 person-years among women). They went on to calculate hazard ratios for death among those patients with diabetes compared with those without diabetes to learn more about specific associations. The following hazard ratios were determined after adjusting for age, sex, smoking status, and BMI: 1.80 (95% confidence interval [CI], 1.71-1.90) for death from any cause; 1.25 (95% CI, 1.19-1.31) for death from cancer; 2.32 (95% CI, 2.11-2.56) for death from vascular causes; and 1.73 (95% CI, 1.62-1.85) for death from other causes. Researchers found that there was a moderate association between diabetes and death from cancers of the liver, pancreas, colorectum, ovary, breast, bladder, and lung. There was also an association between diabetes and deaths from liver disease, renal disease, pneumonia, other infectious diseases, mental disorders, external causes, intentional self-harm, nonhepatic digestive diseases, nervous system disorders, and chronic pulmonary disease. Patients with diabetes were also more likely to have a decreased life span. According to the findings, a 50-year-old with diabetes died about 6 years earlier than someone without diabetes. In addition, about 58% of the survival difference at 50 years of age could be attributed to vascular death, whereas 9% of the difference could be attributed to cancer, and 30% could be attributed to noncancer, nonvascular deaths. Researchers believe there are strengths to their study, including the large sample size and an extended follow-up period, but they also acknowledged several limitations. These included residual bias that may remain due to possible confounding factors and the study’s inability to address the role of glucose-lowering agents in regard to cancer risk.