All-Cause and Cardiovascular Mortality in Middle-Aged People With Type 2 Diabetes Compared With People Without Diabetes in a Large U.K. Primary Care Database

OBJECTIVE

Middle-aged people with diabetes have been reported to have significantly higher risks of cardiovascular events than people without diabetes. However, recent falls in cardiovascular disease rates and more active management of risk factors may have abolished the increased risk. We aimed to provide an up-to-date assessment of the relative risks associated with type 2 diabetes of all-cause and cardiovascular mortality in middle-aged people in the U.K.

RESEARCH DESIGN AND METHODS

Using data from the General Practice Research Database, from 2004 to 2010, we conducted a cohort study of 87,098 people, 40–65 years of age at baseline, comparing 21,798 with type 2 diabetes and 65,300 without diabetes, matched on age, sex, and general practice. We produced hazard ratios (HRs) for mortality and compared rates of blood pressure testing, cholesterol monitoring, and use of aspirin, statins, and antihypertensive drugs.

RESULTS

People with type 2 diabetes, compared with people without diabetes, had a twofold increased risk of all-cause mortality (HR 2.07 [95% CI 1.95–2.20], adjusted for smoking) and a threefold increased risk of cardiovascular mortality (3.25 [2.87–3.68], adjusted for smoking). Women had a higher relative risk than men, and people <55 years of age had a higher relative risk than those >55 years of age. Monitoring and medication rates were higher in those with diabetes (all P < 0.001).

CONCLUSIONS

Despite efforts to manage risk factors, administer effective treatments, and develop new therapies, middle-aged people with type 2 diabetes remain at significantly increased risk of death.In the U.K., cardiovascular disease (CVD) mortality rates in adults have fallen dramatically in recent years (1), by >40% in those 35–69 years of age during 2000–2010 alone (2). The fall in the rates of CVD in the general adult U.K. population may be attributed in part to using aspirin, hydroxymethylglutaryl-CoA reductase inhibitors (statins), and antihypertensive drugs and successfully incorporating lifestyle interventions, in particular reducing smoking (3). In people with type 2 diabetes, who are at increased risk of death from CVD, evidence has shown that statins, antihypertensive drugs (4), and smoking cessation (3,5) reduce the incidence of CVD (6,7). Consequently, these interventions, in addition to weight management strategies to target obesity, a known risk factor for CVD events (3), have been incorporated into the various clinical guidelines, national standards, and incentives relating to managing diabetes (8–10) and implemented by general practitioners with the aim of reducing the risk of complications.The magnitude of the increase in risk of CVD and all-cause mortality in middle-aged people with diabetes, compared with those without diabetes, has been reported at two to four times higher, but these estimates are largely based on data from the 1990s or earlier (11–16). Given that the rates of CVD mortality in the general population have rapidly fallen in recent years (2), and since 2004, the remuneration for general practice actively rewards intensive management for cardiovascular risk factors in people with diabetes (10), the differences may have narrowed even in the past 8 years. Most studies with post-2000 data on relative risk have not distinguished type 1 from type 2 diabetes (17–20), or have been restricted to newly diagnosed type 2 diabetes (21,22). One exception, reporting relative risks for prevalent type 2 diabetes, was the National Diabetes Audit in England (23). Using follow-up data from 2008 to 2009, they presented standardized mortality ratios in the absence of a nondiabetic comparator group; the report’s authors proposed that their results need replicating using survival analysis methods. Using data from the General Practice Research Database (GPRD), we aimed to provide a more up-to-date assessment of the risk of mortality in middle-aged people with prevalent type 2 diabetes in England, overcoming the acknowledged limitation of the National Diabetes Audit study and additionally considering mortality from CVD.