Mortality in childhood-onset type 1 diabetes: a population-based study

OBJECTIVE: To describe the age- and sex-specific mortality in a cohort of young type 1 diabetic patients and to analyze the causes of death with special focus on suicide, accidents, and unexplained deaths. RESEARCH DESIGN AND METHODS: A population-based incident childhood diabetes register, covering onset cases since 1 July 1977, was linked to the Swedish Cause of Death Register up to 31 December 2000. The official Swedish population register was used to calculate age- and sex-standardized mortality rates (SMRs), excluding neonatal deaths. To analyze excess risks for specific diagnoses, case subjects were compared with five nondiabetic control subjects, matched by age, sex, and year of death. Death certificates were collected for all case and control subjects. For case subjects with an unclear diagnosis, hospital records and/or forensic autopsy reports were obtained. RESULTS: Mean age- and sex-SMR was 2.15 (95% CI 1.70-2.68) and tended to be higher among females (2.65 vs. 1.93, P = 0.045). Mean age at death was 15.2 years (range 1.2-27.3) and mean duration 8.2 years (0-20.7). Twenty-three deaths were clearly related to diabetes; 20 died of diabetic ketoacidosis. Only two case subjects died with late diabetes complications (acute coronary infarction). Thirty-three case subjects died with a diagnosis not directly related to diabetes; 7 of them committed suicide, and 14 died from accidents. There was no significant difference in traffic accidents (odds ratio 1.02 [95% CI 0.40-2.37]). Obvious suicide tended to be increased but not statistically significantly so (1.55 [0.54-3.89]). Seventeen diabetic case subjects were found deceased in bed without any cause of death found at forensic autopsy. Only two of the control subjects died of similar unexplained deaths. CONCLUSIONS: In a well-developed health care system, there is still a significant excess mortality in young type 1 diabetic patients. We confirm a very large proportion of unexplained deaths in bed, which should be further studied. There is no clear excess death rate caused by suicide or traffic accidents among young diabetic subjects.     

Impact of NIDDM on mortality and causes of death in Pima Indians.

OBJECTIVE--To compare overall and cause-specific death rates for diabetic and nondiabetic Pima Indians. RESEARCH DESIGN AND METHODS--This community-based study determined overall and cause-specific death rates in persons with and without NIDDM in the Pima population. Underlying causes of death for the 10-yr period from 1975 to 1984 were derived from review of death certificates and medical records. Diabetes diagnoses were based on an ongoing diabetes study initiated by the National Institutes of Health in 1965. RESULTS--Of the 512 deaths, 241 were in Pima Indians with NIDDM; 203 (84%) of the deaths in diabetic subjects were attributed to natural causes (46 diabetic nephropathy, 35 IHD, 29 infections, 20 malignant neoplasms, 20 alcoholic liver disease, 18 stroke, 35 other causes). For natural causes, the overall age-sex-adjusted death rate in diabetic subjects was 1.7 times (95% CI 1.4-2.2) that in nondiabetic subjects. Longer duration of diabetes was significantly related to mortality, an association that was stronger in women than in men. Rates of death from diabetic nephropathy, IHD, and infections (but not stroke) were each significantly related to longer diabetes duration. Together, diabetic nephropathy and IHD accounted for 90% of the excess death rate among diabetic, compared with nondiabetic, Pimas. CONCLUSIONS--In Pima Indians, NIDDM has a significant adverse effect on death rates that is directly related to diabetes duration, especially for deaths from diabetic nephropathy, IHD, or infections. Among the Pima, diabetic nephropathy is the leading cause of death, and IHD ranks second--a variation from other populations (in which IHD ranks first), probably partly attributable to a much younger age of onset of diabetes among the Pima than in the U.S. white population.     

Mortality and causes of death in a national sample of diabetic patients in Taiwan

OBJECTIVE: To determine the mortality rate, causes of death, and standardized mortality ratio (SMR) in Taiwanese diabetic patients. RESEARCH DESIGN AND METHODS: A cohort of 256036 diabetic patients (118855 men and 137181 women, aged 61.2 +/- 15.2 years) using the National Health Insurance were assembled during the years 1995-1998 and followed up to the end of 2001. Deaths were verified by indexing to the National Register of Deaths. Underlying causes of death were determined from death certificates coded according to the ninth revision of the International Classification of Diseases. The general population of Taiwan was used as reference for SMR calculation. RESULTS: With a total of 1124348.4 person-years of follow-up, 43888 patients died and the crude mortality rate was 39.0/1000 person-years. Mortality rates increased with age, and diabetic men had a significantly higher risk of death than women. However, mortality rate ratio for men versus women attenuated with increasing age. The overall SMR was 1.63 (1.62-1.65), and SMRs also attenuated in the elderly. Causes of death ascribed to diabetes; cancer; cardiopulmonary disease; stroke; disease of arteries, arterioles, and capillaries; nephropathy; infection; digestive diseases; accidents; and suicide were 28.8, 18.5, 9.0, 10.5, 0.3, 4.8, 6.4, 7.9, 3.2, and 0.8%, respectively. CONCLUSIONS: Approximately 71.2% of the diabetes-related deaths would not be ascribed to diabetes on death certificates in Taiwan. The diabetic men have higher risk of dying than women, and diabetic patients have excess mortality when compared with the general population. For underlying causes of death not listed as diabetes, total cardiovascular death, including cardiopulmonary disease, stroke, and disease of arteries, arterioles, and capillaries, is the most common cause of death, followed by cancer.     

Diagnosis of type 2 diabetes at an older age: effect on mortality in men and women

OBJECTIVE: To compare the mortality of people who were diagnosed with type 2 diabetes over 65 years of age with that of nondiabetic individuals. RESEARCH DESIGN AND METHODS: Using a population-based diabetes information system for an observational cohort study in Tayside, Scotland, people who were diagnosed with type 2 diabetes over the age of 65 years between 1993 and 2002 were identified. Nondiabetic comparators, matched for age and sex, were identified from the nondiabetic population. The two cohorts were followed up for mortality and cardiovascular mortality according to death certification records. RESULTS: There were 3,594 people with type 2 diabetes (48% male) and 7,188 matched comparators identified in the study. Over a mean follow-up period of 4.6 +/- 2.9 years for 3,594 people with type 2 diabetes and 7,188 comparators, 909 (25.3%) patients in the diabetic cohort and 1,651 (23.0%) in the nondiabetic cohort died. The adjusted relative risk for mortality in the diabetic cohort compared with the nondiabetic cohort was 1.06 (95% CI 0.94-1.19) for men and 1.29 (1.15-1.45) for women. Cardiovascular deaths accounted for 49.4% of the deaths in people with and 45.2% in those without diabetes (adjusted relative risk 1.01 [0.93-1.10]). CONCLUSIONS: Men diagnosed with type 2 diabetes over the age of 65 years have no excess mortality compared with their nondiabetic counterparts, a finding that was not replicated for women.     

Cause-specific mortality in a population with diabetes: South Tees Diabetes Mortality Study.

OBJECTIVE: To describe the mortality of a population with diabetes compared with the local nondiabetic population, using age-, sex-, and cause-specific death rates and relative and absolute differences in death rates. RESEARCH DESIGN AND METHODS: A population-based cohort of 4,842 people with diabetes living within South Tees, U.K., was identified and followed from 1 January 1994 to 31 December 1999. Causes of death were obtained from death certificates, and mortality rates were compared with the nondiabetic population of the same area for the same time period. RESULTS: There were 1,205 deaths (24.9%) in the study population during the 6 years of study. For type 2 diabetes, mortality from cardiovascular causes was significantly increased in both sexes and at all ages. Relative death rates for the age band 40-59 years were 5.47 (95% CI 4.18-7.15) for men and 5.60 (3.44-9.14) for women. The relative death rates declined with age for both sexes, but absolute excess mortality increased with age. There were no consistent differences in noncardiovascular death rates, other than for renal disease. Similar outcomes were found for type 1 diabetes, although these results were limited by a much smaller population size. People with diabetes and renal impairment had significantly higher mortality than people with diabetes alone, with a rate ratio of 7.27 for people with type 2 diabetes aged 40-59 years. CONCLUSIONS: In an area of the U.K. with high cardiovascular death rates, people with diabetes had significantly higher cardiovascular death rates than people without diabetes. Interventions targeted at cardiovascular risk factors should be used to try and reduce this excess premature mortality, which is especially high in those with renal impairment.     

Diabetes and the risk of infection-related mortality in the U.S

OBJECTIVE--To determine whether diabetes predicts infection-related mortality and to clarify the extent to which this relationship is mediated by comorbid conditions that may themselves increase risk of infection. RESEARCH DESIGN AND METHODS--We performed a retrospective cohort study using the Second National Health and Nutrition Examination Survey Mortality Study of 9,208 adults aged 30-74 years in 1976-1980. We defined demographic variables, diabetes, cardiovascular disease (CVD), and smoking by self-report; BMI, blood pressure, and serum cholesterol from baseline examination; and cause-specific mortality from death certificates. RESULTS--Over 12-16 years of follow-up, 36 infection-related deaths occurred among 533 adults with diabetes vs. 265 deaths in 8,675 adults without diabetes (4.7 vs. 1.5 per 1,000 person-years, P < 0.001). Diabetes (RR 2.0, 95% CI 1.2-3.2) and congestive heart failure (2.8, 1.6-5.1) were independent predictors of infection-related mortality after simultaneous adjustment for age, sex, race, poverty status, smoking, BMI, and hypertension. After subdividing infection-related deaths into those with (n = 145) and without (n = 156) concurrent cardiovascular diagnoses at the time of death, diabetic adults were at risk for infection-related death with CVD (3.0, 1.8-5.0) but not without CVD (1.0, 0.5-2.2). CONCLUSIONS--These nationally representative data suggest that diabetic adults are at greater risk for infection-related mortality, and the excess risk may be mediated by CVD.     

Type 2 diabetes as a "coronary heart disease equivalent": an 18-year prospective population-based study in Finnish subjects

OBJECTIVE: The purpose of this study was to investigate the hypothesis that coronary heart disease (CHD) mortality in diabetic subjects without prior evidence of CHD is equal to that in nondiabetic subjects with prior myocardial infarction or any prior evidence of CHD. RESEARCH DESIGN AND METHODS: During an 18-year follow-up total, cardiovascular disease (CVD) and CHD deaths were registered in a Finnish population-based study of 1,373 nondiabetic and 1,059 diabetic subjects. RESULTS: Adjusted multivariate Cox hazard models indicated that diabetic subjects without prior myocardial infarction, compared with nondiabetic subjects with prior myocardial infarction, had a hazard ratio (HR) of 0.9 (95% CI 0.6-1.5) for the risk of CHD death. The corresponding HR was 0.9 (0.5-1.4) in men and 1.9 (0.6 -6.1) in women. Diabetic subjects without any prior evidence of CHD (myocardial infarction or ischemic electrocardiogram [ECG] changes or angina pectoris), compared with nondiabetic subjects with prior evidence of CHD, had an HR of 1.9 (1.4-2.6) for CHD death (men 1.5 [1.0-2.2]; women 3.5 [1.8-6.8]). The results for CVD and total mortality were quite similar to those for CHD mortality. CONCLUSIONS: Diabetes without prior myocardial infarction and prior myocardial infarction without diabetes indicate similar risk for CHD death in men and women. However, diabetes without any prior evidence of CHD (myocardial infarction or angina pectoris or ischemic ECG changes) indicates a higher risk than prior evidence of CHD in nondiabetic subjects, especially in women.     

A population-based study of diabetes mortality

In a population-based investigation among the residents of Rochester, Minnesota, the diabetes mortality rate was 8.5 per 100,000 person-years with diabetes as the underlying cause of death, 31.5 per 100,000 person-years with diabetes as an underlying or contributory cause, and 82.7 per 100,000 person-years if all deaths among diabetic individuals were counted. Diabetes was not mentioned on the certificate in 62% of the 428 diabetic deaths during 1965-1974. When the clinical characteristics of the subgroup of mortality cases in 1969 were compared with those of the prevalence cases on 1 January 1970, it was found that mortality cases tended to be older, were more often on insulin therapy, and were more likely to have macro- and microvascular complications. Because mortality data are sometimes used to infer trends and characteristics for the diabetic population at large, it is important to recognize these biases.     

Diabetes reporting as a cause of death: results from the Translating Research Into Action for Diabetes (TRIAD) study

OBJECTIVE: To determine the frequency of reporting of diabetes on death certificates of decedents with known diabetes, define factors associated with reporting of diabetes, and describe trends in reporting over time. RESEARCH DESIGN AND METHODS: Data were obtained from 11,927 participants with diabetes who were enrolled in the Translating Research Into Action for Diabetes study, a multicenter prospective observational study of diabetes care in managed care. Data on decedents (n = 540) were obtained from the National Death Index. The primary dependent variable was the presence of ICD-10 codes for diabetes on the death certificate. Covariates included age at death, sex, race/ethnicity, education, income, duration of diabetes, type of diabetes, diabetes treatment, smoking status, and number of comorbidities. RESULTS: Diabetes was recorded on 39% of death certificates and as the underlying cause of death for 10% of decedents with diabetes. Diabetes was significantly less likely to be reported on the death certificates of decedents with diabetes dying of cancer. Predictors of recording diabetes anywhere on the death certificate included longer duration of diabetes and insulin treatment. Longer duration of diabetes, insulin treatment, and fewer comorbidities were associated with recording of diabetes as the underlying cause of death. CONCLUSIONS: Diabetes is much more likely to be reported on the death certificates of diabetic individuals who die of cardiovascular causes. Reporting of diabetes on death certificates has been stable over time. Death certificates underestimate the prevalence of diabetes among decedents and present a biased picture of the causes of death among people with diabetes.     

Insulin-treated type 2 diabetes is associated with a decreased survival in heart failure patients after cardiac resynchronization therapy

Background: Cardiac resynchronization therapy (CRT) improves cardiac performance and survival in patients with congestive heart failure. Recent observations suggest that diabetes is associated with a worse outcome in these patients. The aim of the study was to investigate the effect of diabetes and insulin treatment on outcome after CRT. Methods: Diabetic status and insulin treatment were assessed in 447 patients who underwent CRT (males 80.8%, mean age 65.7 ± 9.7 years, ejection fraction 29.9 ± 6.11%). Patients were stratified in three groups according to the presence or absence of diabetes and insulin treatment. Results: Nondiabetic patients were 366 (79.6%), noninsulin‐treated diabetic patients 62 (13.9%), insulin‐treated diabetic patients 29 (6.5%). The estimated death rate was 5.15 per 100 patients‐year in the nondiabetic group, 8.63 in noninsulin‐treated diabetics (HR 1.59, P = 0.240), and 15.84 in insulin‐treated diabetics (HR 3.05, P = 0.004). Cardiac mortality accounted for 81% of deaths in nondiabetic patients and for 56% of deaths in diabetic patients. Diabetic patients tended to have a worse recovery of left ventricular ejection fraction over time (P = 0.057) and of the distance at 6‐minute walking test (6MWT) (P = 0.018). Conclusions: Insulin‐treated diabetes is associated with a worse functional recovery and a higher mortality in patients with advanced heart failure after CRT. While cardiac death accounts for the majority of deaths in nondiabetic patients, a relevant proportion of the mortality in diabetic patients seem to result from noncardiac causes.     

Diabetes duration and cause-specific mortality in the Verona Diabetes Study

OBJECTIVE: To examine the 10-year mortality and effect of diabetes duration on overall and cause-specific mortality in diabetic subjects in the Verona Diabetes Study (VDS). RESEARCH DESIGN AND METHODS: Records from diabetes clinics, family physicians, and a drug consumption database were used to identify 5,818 subjects > or =45 years of age with type 2 diabetes who were alive and residing in Verona, Italy on 31 December 1986. Vital status of each subject was ascertained on 31 December 1996. Underlying causes of death were determined from death certificates. Death rates and death rate ratios (DRRs) were computed and standardized to the population of Verona in 1991. RESULTS: During the study, 2,328 subjects died; 974 deaths were attributable to cardiovascular disease, 517 to neoplasms, 324 to diabetes-related diseases, 134 to digestive diseases, 250 to other natural causes, and 48 to external causes. There were 81 subjects who died of unknown causes. Death rates from natural causes were higher in men than in women (DRR 1.4, 95% CI 1.2-1.5) and rose in both sexes with increasing duration of diabetes (P = 0.001). Among the natural causes of death, those for diabetes-related diseases were strongly related to diabetes duration (P = 0.001). a modest relationship with duration was also found for ischemic heart disease in men (P = 0.07). CONCLUSIONS: Cardiovascular disease was the principal cause of death among people with type 2 diabetes in the VDS. Rates for natural causes of death rose with increasing duration of diabetes. Deaths from diabetes-related diseases in both sexes and from ischemic heart disease in men were largely responsible for this increase.     

Predictors of mortality over 8 years in type 2 diabetic patients: Translating Research Into Action for Diabetes (TRIAD)

OBJECTIVE

To examine demographic, socioeconomic, and biological risk factors for all-cause, cardiovascular, and noncardiovascular mortality in patients with type 2 diabetes over 8 years and to construct mortality prediction equations.

RESEARCH DESIGN AND METHODS

Beginning in 2000, survey and medical record information was obtained from 8,334 participants in Translating Research Into Action for Diabetes (TRIAD), a multicenter prospective observational study of diabetes care in managed care. The National Death Index was searched annually to obtain data on deaths over an 8-year follow-up period (2000–2007). Predictors examined included age, sex, race, education, income, smoking, age at diagnosis of diabetes, duration and treatment of diabetes, BMI, complications, comorbidities, and medication use.

RESULTS

There were 1,616 (19%) deaths over the 8-year period. In the most parsimonious equation, the predictors of all-cause mortality included older age, male sex, white race, lower income, smoking, insulin treatment, nephropathy, history of dyslipidemia, higher LDL cholesterol, angina/myocardial infarction/other coronary disease/coronary angioplasty/bypass, congestive heart failure, aspirin, β-blocker, and diuretic use, and higher Charlson Index.

CONCLUSIONS

Risk of death can be predicted in people with type 2 diabetes using simple demographic, socioeconomic, and biological risk factors with fair reliability. Such prediction equations are essential for computer simulation models of diabetes progression and may, with further validation, be useful for patient management.In 2007, diabetes was the seventh leading cause of death in the U.S. with >71,000 death certificates listing diabetes as the underlying cause of death (1,2). Diabetes is reported as the underlying cause of death on 10–15% of death certificates of decedents with diabetes and is reported anywhere on the death certificate for 40% of decedents with diabetes (3–5). Since a diagnosis of diabetes cannot be ascertained from death certificates, the best way to examine mortality in people with diabetes is to use a prospective observational cohort design and follow diabetic participants until death. Unfortunately, few such studies have been undertaken in nationally representative populations of people with diabetes. Although many investigators have assessed risk factors for cardiovascular mortality, there are few published prediction models. Such models are needed to construct computer models to simulate the progression of diabetes, and may, with further validation, be useful for clinical decision making.Translating Research Into Action for Diabetes (TRIAD), which began in 1999, was a prospective observational study of people with diabetes enrolled in managed care health plans in the U.S. The primary objective of TRIAD was to study how health plan, provider, and patient characteristics impact the processes and outcomes of diabetes care. TRIAD enrolled ∼12,000 diabetic patients from eight geographically distinct regions in the U.S. We previously reported on the demographic, socioeconomic, and biological risk factors for 4-year mortality in the TRIAD population (6). Since our study was published, two studies have reported prediction equations for mortality in patients with type 2 diabetes. One was performed in Chinese patients living in Hong Kong (7). The other was limited to patients initially prescribed a single oral hypoglycemic agent (8).The objective of this study was to assess longer-term mortality in a large, diverse, U.S. population with type 2 diabetes and to create prediction equations for all-cause, cardiovascular, and noncardiovascular mortality among people with clinically diagnosed type 2 diabetes.     

Recent trends in cardiovascular complications among men and women with and without diabetes

OBJECTIVE: To compare recent trends in cardiovascular disease (CVD) outcomes among men and women with diabetes with those in the nondiabetic population. RESEARCH DESIGN AND METHODS: We conducted a retrospective cohort study using provincial health claims data to identify adults with (n = 670,602) and without (n = 9,190,721) diabetes living in Ontario, Canada, between 1 April 1992 and 31 March 2000. We compared changes in the annual age-/sex-adjusted rates and numbers of subjects admitted for acute myocardial infarction (AMI) and stroke and of deaths from AMI, stroke, and all causes between those with and without diabetes. RESULTS: Over the 8-year period, the rate of patients admitted for AMI and stroke fell to a greater extent in the diabetic than the nondiabetic population (AMI: -15.1 vs. -9.1%, P < 0.0001; stroke: -24.2 vs. 19.4%, P < 0.0001). Diabetic patients experienced similar reductions in case-fatality rates related to AMI and stroke than those without diabetes (-44.1 vs. -33.2%, P = 0.1; -17.1 vs. -16.6%, P = 0.9, respectively). Declines in all-cause mortality were also comparable in the two populations. Over the same period, the number of diabetes cases increased from 405,471 to 670,602. Thus, while CVD rates fell, the number of events occurring in this population rose substantially (AMI: +44.6%, stroke: +26.1%, AMI deaths: +17.2%, and stroke deaths: +13.2%). CONCLUSIONS: Our findings demonstrate a significant reduction in the rate of people affected by CVD within the diabetic population. However, as the number of people with diabetes rises, so may the absolute burden of CVD in our society.     

An explanation for the increase in heart disease mortality rates in diabetic Pima Indians: effect of renal replacement therapy

OBJECTIVE: Diabetic nephropathy (DN) became the leading cause of death in diabetic Pima Indians in the 1970s, but was superseded by ischemic heart disease (IHD) in the 1980s. This study tests the hypothesis that the rise in the IHD death rate between 1965 and 1998 is attributable to access to renal replacement therapy (RRT). RESEARCH DESIGN AND METHODS: Underlying causes of death were determined among 2,095 diabetic Pima Indians > or = 35 years old during four 8.5-year time intervals. To assess the effect of access to RRT on IHD death rates, trends were reexamined after subjects receiving RRT were classified as if they had died of DN. RESULTS: During a median follow-up of 11.1 years (range 0.01-34), 818 subjects died. The age- and sex-adjusted DN death rate decreased over the 34-year study (P = 0.05), whereas the IHD death rate increased from 3.3 deaths/1,000 person-years (95% CI 1.4-5.2) to 6.3 deaths/1,000 person-years (95% CI 4.5-8.0; P = 0.03). After 151 subjects on RRT were reclassified as if they had died of DN, the death rate for DN increased from 4.8 deaths/1,000 person-years (95% CI 2.6-7) to 11.3 deaths/1,000 person-years (95% CI 9-13.6; P = 0.0007), whereas the increase in the IHD death rate disappeared (P = 0.57). CONCLUSIONS: The incidence rate of renal failure attributable to diabetes has increased rapidly over the past 34 years in Pima Indians. IHD has emerged as the leading cause of death due largely to the availability of RRT and to changes in the pattern of death among those with DN.     

Trends in death rates among U.S. adults with and without diabetes between 1997 and 2006: findings from the National Health Interview Survey

OBJECTIVE

To determine whether all-cause and cardiovascular disease (CVD) death rates declined between 1997 and 2006, a period of continued advances in treatment approaches and risk factor control, among U.S. adults with and without diabetes.

RESEARCH DESIGN AND METHODS

We compared 3-year death rates of four consecutive nationally representative samples (1997–1998, 1999–2000, 2001–2002, and 2003–2004) of U.S. adults aged 18 years and older using data from the National Health Interview Surveys linked to National Death Index.

RESULTS

Among diabetic adults, the CVD death rate declined by 40% (95% CI 23–54) and all-cause mortality declined by 23% (10–35) between the earliest and latest samples. There was no difference in the rates of decline in mortality between diabetic men and women. The excess CVD mortality rate associated with diabetes (i.e., compared with nondiabetic adults) decreased by 60% (from 5.8 to 2.3 CVD deaths per 1,000) while the excess all-cause mortality rate declined by 44% (from 10.8 to 6.1 deaths per 1,000).

CONCLUSIONS

Death rates among both U.S. men and women with diabetes declined substantially between 1997 and 2006, reducing the absolute difference between adults with and without diabetes. These encouraging findings, however, suggest that diabetes prevalence is likely to rise in the future if diabetes incidence is not curtailed.Diabetes has been associated with an average 10 years of life lost for individuals diagnosed during middle age (1). Fortunately, numerous evidence-based interventions exist, ranging from glycemic and cardiovascular disease (CVD) risk factor control to early screening for diabetes complications (2). These have been paralleled by population-wide improvements in glycemic control, CVD risk factors, and rates of several diabetes complications (3–5). Despite these improvements, it remains unclear whether longevity has increased uniformly among diabetic populations. Studies in specific diabetic cohorts in Framingham, Minnesota, and North Dakota suggest mortality declined during the 1990s (6–8). Analyses of consecutive cohorts of the U.S. population from the 1970s through the 1990s, however, found that all-cause and CVD death rates declined among diabetic men but not diabetic women (9,10). However, no national studies have examined mortality trends among the U.S. diabetic population since the 1990s, and the intervening years have been a period of continued advances in treatment approaches and risk factor levels. Newly available mortality follow-up data linked to the National Health Interview Survey (NHIS) provide a unique opportunity to determine whether CVD and all-cause mortality has improved among the U.S. population during recent decades as well as whether the excess mortality associated with diabetes has declined (11,12).     

Should diabetes be considered a coronary heart disease risk equivalent?: results from 25 years of follow-up in the Renfrew and Paisley survey

OBJECTIVE: The purpose of our study was to confirm or refute the view that diabetes be regarded as a coronary heart disease (CHD) risk equivalent and to test for sex differences in mortality. RESEARCH DESIGN AND METHODS: This was a prospective cohort study of 7,052 men and 8,354 women aged 45-64 years from Renfrew and Paisley, Scotland, who were first screened in 1972-1976 and followed for 25 years. All-cause mortality was calculated as death per 1,000 person-years. A Cox proportional hazards model was used to adjust survival for age, smoking habit, blood pressure, serum cholesterol, BMI, and social class. RESULTS: There were 192 deaths in 228 subjects with diabetes and 2,016 deaths in 3,076 subjects with CHD. The highest mortality was in the group with both diabetes and CHD (100.2 deaths/1,000 person-years in men, 93.6 in women) and the lowest in the group with neither (29.2 deaths/1,000 person-years in men, 19.4 in women). Men and women with diabetes only and CHD only formed an intermediate risk group. The adjusted hazard ratio (HR) for CHD mortality in men with diabetes only compared with men with CHD only was 1.17 (95% CI 0.78-1.74; P = 0.56). Corresponding HR for women was 1.97 (1.27-3.08; P = 0.003). CONCLUSIONS: Diabetes without previous CHD carries a lifetime risk of vascular death as high as that for CHD alone. Women may be at particular risk. Our data support the view that cardiovascular risk factors in diabetes should be treated as aggressively as in people with CHD.     

All-cause mortality in the Canterbury (New Zealand) insulin-treated Diabetic Registry population

OBJECTIVE: To establish all-cause death rates and life expectancies of and risk factors for mortality in insulin-treated diabetic individuals living in Canterbury, New Zealand. RESEARCH DESIGN AND METHODS: Insulin-treated diabetic subjects (n = 1,008) on the Canterbury Diabetes Registry were tracked over 9 years, and their vital status was determined. Death rates were standardized using direct and indirect methods. Cox proportional hazard regression was used to model the effects of demographic and clinical covariates on survival time. RESULTS: At study entry, age ranged from 2.9 to 92.7 years, with mean 48.7 +/- 20.4 years; age at diagnosis was 0.2-88.9 years, mean 34.5 +/- 20.0 years; and duration of diabetes was 0.1-58.5 years, mean 14.0 +/- 10.6 years. There were 303 deaths in 7,372 person-years of follow-up with a standardized mortality ratio (SMR) of 2.6 (95% CI 2.4-3.0). Relative mortality was greatest for those aged 30-39 years (SMR 9.2 [4.8-16.2]). The death rate for the diabetic cohort standardized against the Segi world standard population was 16.2 per 1,000. Attained age, sex, and clinical subtype were significant predictors of mortality The SMR for subjects with type 1 diabetes and age at onset <30 years was 3.7 (CI 2.7-5.0), 2.2 (1.8-2.6) for those with onset > or =30 years, and 3.1 (2.5-3.7) for subjects suspected of having latent autoimmune diabetes in adulthood or insulin-treated type 2 diabetes. Life expectancy was reduced for both sexes at all ages. CONCLUSIONS: Mortality rates for insulin-treated diabetic individuals remain high, resulting in shortened life spans relative to the general population. Marked differences in mortality exist between clinical groups of subjects. Further research is needed to improve diabetes classification and to clarify differences in health outcomes.     

Temporal trends in recording of diabetes on death certificates: results from Translating Research Into Action for Diabetes (TRIAD)

OBJECTIVE

To determine the frequency that diabetes is reported on death certificates of decedents with known diabetes and describe trends in reporting over 8 years.

RESEARCH DESIGN AND METHODS

Data were obtained from 11,927 participants with diabetes who were enrolled in Translating Research into Action for Diabetes, a multicenter prospective observational study of diabetes care in managed care. Data on decedents (N = 2,261) were obtained from the National Death Index from 1 January 2000 through 31 December 2007. The primary dependent variables were the presence of the ICD-10 codes for diabetes listed anywhere on the death certificate or as the underlying cause of death.

RESULTS

Diabetes was recorded on 41% of death certificates and as the underlying cause of death for 13% of decedents with diabetes. Diabetes was significantly more likely to be reported on the death certificate of decedents dying of cardiovascular disease than all other causes. There was a statistically significant trend of increased reporting of diabetes as the underlying cause of death over time (P < 0.001), which persisted after controlling for duration of diabetes at death. The increase in reporting of diabetes as the underlying cause of death was associated with a decrease in the reporting of cardiovascular disease as the underlying cause of death (P < 0.001).

CONCLUSIONS

Death certificates continue to underestimate the prevalence of diabetes among decedents. The increase in reporting of diabetes as the underlying cause of death over the past 8 years will likely impact estimates of the burden of diabetes in the U.S.In 2005, the National Center for Health Statistics ranked diabetes as the fifth leading cause of death in the U.S (1). Although it is difficult to determine the true extent to which diabetes should be recorded as a cause of death, this is likely an underestimate since diabetes is listed anywhere on the death certificate of fewer than half of people with known diabetes who die (2–5). Although using mortality data for epidemiologic studies is a common practice, it has drawbacks. When one studies mortality rates over time using death certificates one generally assumes that the likelihood of recording the condition remains constant over time, so that observed changes in mortality reflect true changes in the rate and not simply changes in recording practices. The last national study investigating trends in reporting of diabetes on death certificates used the 1986 and 1993 National Mortality Follow-back Survey and documented consistent underreporting over time (2). One smaller, more recent study looking at the sensitivity and specificity of reporting of diabetes on death certificates reported similar results (4).We hypothesize that diabetes reporting on death certificates may have improved since 2000 because of the increasing prevalence of diabetes and the increased media attention to diabetes. The objective of this study was to determine the frequency of reporting of diabetes on death certificates of decedents with known diabetes and to describe trends over 8 years using data from Translating Research into Action for Diabetes (TRIAD). TRIAD was ideal for this study because it involved a racially and ethnically diverse sample of adults with diabetes from six sites across the United States and because all participants had been diagnosed with diabetes for at least 1 year before enrollment.