Mortality in diabetes mellitus: experience of a geographically defined population

Sex differences in the association between diabetes and cancer: a systematic review and meta-analysis of 121 cohorts including 20 million individuals and one million events

AIMS/HYPOTHESIS

Diabetes has been shown to be a risk factor for some cancers. Whether diabetes confers the same excess risk of cancer, overall and by site, in women and men is unknown.

METHODS

A systematic search was performed in PubMed for cohort studies published up to December 2016. Selected studies reported sex-specific relative risk (RR) estimates for the association between diabetes and cancer adjusted at least for age in both sexes. Random-effects meta-analyses with inverse-variance weighting were used to obtain pooled sex-specific RRs and women-to-men ratios of RRs (RRRs) for all-site and site-specific cancers.

RESULTS

Data on all-site cancer events (incident or fatal only) were available from 121 cohorts (19,239,302 individuals; 1,082,592 events). The pooled adjusted RR for all-site cancer associated with diabetes was 1.27 (95% CI 1.21, 1.32) in women and 1.19 (1.13, 1.25) in men. Women with diabetes had ~6% greater risk compared with men with diabetes (the pooled RRR was 1.06, 95% CI 1.03, 1.09). Corresponding pooled RRRs were 1.10 (1.07, 1.13) for all-site cancer incidence and 1.03 (0.99, 1.06) for all-site cancer mortality. Diabetes also conferred a significantly greater RR in women than men for oral, stomach and kidney cancer, and for leukaemia, but a lower RR for liver cancer.

CONCLUSIONS/INTERPRETATION

Diabetes is a risk factor for all-site cancer for both women and men, but the excess risk of cancer associated with diabetes is slightly greater for women than men. The direction and magnitude of sex differences varies by location of the cancer.

Diabetes mellitus and mortality from all-causes, cancer, cardiovascular and respiratory disease: evidence from the Health Survey for England and Scottish Health Survey cohorts

BACKGROUND

Diabetes mellitus is associated with differing rates of all-cause and cause-specific mortality compared with the general population; although the strength of these associations requires further investigation. The effects of confounding factors, such as overweight and obesity and the presence of co-morbid cardiovascular disease (CVD), upon such associations also remain unclear. There is thus a need for studies which utilise data from nationally-representative samples to explore these associations further.

METHODS

A cohort study of 204,533 participants aged 16+ years (7,199 with diabetes) from the Health Survey for England (HSE) (1994-2008) and Scottish Health Survey (SHeS) (1995, 1998 and 2003) linked with UK mortality records. Odds ratios (ORs) of all-cause and cause-specific mortality and 95% confidence intervals were estimated using logistic and multinomial logistic regression.

RESULTS

There were 20,051 deaths (1,814 among those with diabetes). Adjusted (age, sex, and smoking status) ORs for all-cause mortality among those with diabetes was 1.68 (95%CI 1.57-1.79). Cause-specific mortality ORs were: cancer 1.26 (1.13-1.42), respiratory diseases 1.25 (1.08-1.46), CVD 1.96 (1.80-2.14) and 'other' causes 2.06 (1.84-2.30). These were not attenuated significantly after adjustment for generalised and/or central adiposity and other confounding factors. The odds of mortality differed between those with and without comorbid CVD at baseline; the ORs for the latter group were substantially increased.

CONCLUSIONS

In addition to the excess in CVD and all-cause mortality among those with diabetes, there is also increased mortality from cancer, respiratory diseases, and 'other' causes. This increase in mortality is independent of obesity and a range of other confounding factors. With falling CVD incidence and mortality, the raised risks of respiratory and cancer deaths in people with diabetes will become more important and require increased health care provision.

Significantly increased risk of cancer in diabetes mellitus patients: A meta-analysis of epidemiological evidence in Asians and non-Asians

Aims/Introduction:  Emerging evidence from observational studies suggests that diabetes mellitus affects the cancer risk. However, whether there are differences in the magnitude of the influence of diabetes among ethnic groups is unknown.

Materials and Methods:  We searched MEDLINE and the Cochrane Library for pertinent articles that had been published as of 4 April 2011, and included them in a meta‐analysis of the risk of all‐cancer mortality and incidence in diabetic subjects.

Results:  A total of 33 studies were included in the meta‐analysis, and they provided 156,132 diabetic subjects for the mortality analysis and 993,884 for the incidence analysis. Cancer mortality was approximately 3%, and cancer incidence was approximately 8%. The pooled adjusted risk ratio (RR) of all‐cancer mortality was significantly higher than for non‐diabetic people (RR 1.32 [CI 1.20–1.45] for Asians; RR 1.16 [CI 1.01–1.34] for non‐Asians). Diabetes was also associated with an increased RR of incidence across all cancer types (RR 1.23 [CI 1.09–1.39] for Asians; RR 1.15 [CI 0.94–1.43] for non‐Asians). The RR of incident cancer for Asian men was significantly higher than for non‐Asian men (P = 0.021).

Conclusions:  Diabetes is associated with a higher risk for incident cancer in Asian men than in non‐Asian men. In light of the exploding global epidemic of diabetes, particularly in Asia, a modest increase in the cancer risk will translate into a substantial socioeconomic burden. Our current findings underscore the need for clinical attention and better‐designed studies of the complex interactions between diabetes and cancer. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2011.00183.x, 2012)

Diabetic population mortality and cardiovascular risk attributable to hypertension: a decade follow-up from the Tehran Lipid and Glucose Study

To determine the extent to which burden of cardiovascular disease (CVD) outcomes among diabetic population is attributable to hypertension. Nine-year follow-up data were secured for 7068 participants aged ≥ 20 years old, free from CVD at baseline. Cox proportional hazards regression was implemented to estimate hazard ratios (HRs) of hypertension. Population-attributable hazard fraction (PAHF) was used to assess proportion of diabetic population hazard of CVD events and mortality attributable to hypertension. In the whole population, irrespective of diabetes or hypertension status, incidence rate (95% CI) of CVD, coronary heart disease (CHD), as well as CVD and all-cause mortality per 1000 person-year were 8.3 (7.6-9.0), 7.1 (6.5-7.8), 1.8 (1.5-2.1) and 3.9 (3.5-4.5), respectively. Among diabetes participants, hypertension was a risk factor for CHD (HR = 1.63, 95% CI 1.15-2.03), CVD (HR = 1.74, 95% CI 1.50-2.41), CVD mortality (HR = 1.65, 95% CI 0.87-3.12) and all-cause mortality (HR = 1.53, 95% CI 0.97-2.42). HRs, however, were not statistically significant for all-cause or CVD mortality. PAHFs (%) of hypertension was 27.5 (95% CI 8.3-42.6) for CHD, 29.6 (95% CI 10.6-44.4) for CVD, 27.9 (95% CI - 17.2 to 55.7) for CVD mortality and 22.6 (95% CI - 5.9 to 43.4) for all-cause mortality. Our study shows that there is an excess risk of CVD in hypertensive patients with diabetes related to inadequate control of blood pressure.

Significantly increased risk of cancer in patients with diabetes mellitus: a systematic review and meta-analysis

OBJECTIVE

To conduct a review and meta-analysis of the effect of diabetes mellitus on the incidence of and mortality attributable to cancer at any anatomic site.

METHODS

We performed a search of MEDLINE and the Cochrane Library for pertinent articles published from the origin of these databases to July 5, 2010, and included them in a qualitative review and meta-analysis of the risk of all-cancer incidence and mortality in patients with diabetes.

RESULTS

Among patients with diabetes (n = 257,222) in 12 cohort studies, the cancer incidence was about 7%. The cancer mortality was approximately 3% among patients with diabetes (n = 152,091) in 19 cohort studies. The pooled adjusted risk ratio (RR) of all-cancer incidence was significantly elevated-RR, 1.10 (95% confidence interval [CI], 1.04 to 1.17) overall; RR, 1.14 (CI, 1.06 to 1.23) for men; and RR, 1.18 (CI, 1.08 to 1.28) for women. Diabetes was also associated with an increased RR of mortality across all cancer types-RR, 1.16 (CI, 1.03 to 1.30) overall; RR, 1.10 (CI, 0.98 to 1.23) for men; and RR, 1.24 (CI, 1.11 to 1.40) for women.

CONCLUSION

Cancer prevention and early detection by appropriate screening methods in patients with diabetes should be important components of clinical management and investigation, inasmuch as the exponentially increasing prevalence of diabetes will translate into substantial clinical and public health consequences on a global scale.

Diabetes foot ulceration in a Nigerian hospital: in-hospital mortality in relation to the presenting demographic, clinical and laboratory features

This prospective study assessed in-hospital mortality from diabetic foot ulcer in relation to the demographic, clinical and laboratory features at presentation. Forty-two patients admitted with diabetic foot ulcer were followed up from admission till discharge from hospital. Those who survived or died were compared for any differences in demographic, clinical and laboratory parameters at presentation. The mean age and duration of diabetes for the 42 patients were 56.1 +/- 1.9 years and 8.3 +/- 1.1 years, respectively. The in-hospital mortality rate amongst the 42 subjects was 40.5%. Ulcer grade > or =4, leucocytosis and anaemia were more prevalent in those who demised in comparison with survivors.

Proliferative retinopathy and proteinuria predict mortality rate in type 1 diabetic patients from Fyn County, Denmark

AIMS/HYPOTHESIS

We evaluated the effect of diabetic retinopathy on 25 year survival rate among a population-based cohort of type 1 diabetic patients from Fyn County, Denmark.

METHODS

In 1973 all diabetic patients from Fyn County, Denmark with onset before the age of 30 years as of 1 July 1973 were identified (n=727). In 1981, only 627 patients were still alive and resident in Denmark. Of these, 573 (91%) participated in a clinical baseline examination, in which diabetic retinopathy was graded and other markers of diabetes measured. Mortality rate was examined in a 25 year follow-up and related to the baseline examination.

RESULTS

Of the 573 patients examined at baseline in 1981 and 1982, 297 (51.8%) were still alive in November 2006. Of the others, 256 (44.7%) had died, three (0.5%) had left Denmark and 17 (3%) were of unknown status. Age- and sex-adjusted HRs of mortality rate were 1.01 (95% CI 0.72-1.42) and 2.04 (1.43-2.91) for patients with non-proliferative and proliferative retinopathy respectively at baseline compared with patients with no retinopathy. After adjusting for proteinuria, HR among patients with proliferative retinopathy lost statistical significance, but still remained 1.48 (95% CI 0.98-2.23). The 10 year survival rate of patients who had proliferative retinopathy as well as proteinuria at baseline was 22.2% and significantly lower (p<0.001) than in patients with proteinuria only (70.3%), proliferative retinopathy only (79.0%) or neither (86.6%).

CONCLUSIONS/INTERPRETATION

Proliferative retinopathy and proteinuria predict mortality rate in a population-based cohort of type 1 diabetic patients. In combination they act even more strongly. Non-proliferative diabetic retinopathy did not affect survival rate.

Early mortality from the time of diagnosis of Type 2 diabetes: a 5-year prospective cohort study with a local age- and sex-matched comparison cohort

AIMS

To study patterns and predictors of early mortality in individuals with a new diagnosis of Type 2 diabetes, compared with a local age- and sex-matched comparison cohort.

METHODS

A total of 736 individuals diagnosed with Type 2 diabetes between 1 May 1996 and 30 June 1998 and non-diabetic age- and sex-matched control subjects were studied. Follow-up was 5.25 years. Age- and gender-specific all-cause mortality odds ratios were calculated for the diabetic cohort compared with the non-diabetic comparator group. Mortality odds ratios were ascertained using conditional logistic regression.

RESULTS

There were 147 deaths in the diabetic cohort [cardiovascular (42.2%), cancer (21.1%)]. Compared with the non-diabetic cohort, mortality odds more than doubled [odds ratio (OR) 2.47; 95% confidence interval (CI) 1.74, 3.49]. These increased odds were present in all age bands (including those aged > 75 years at diagnosis) for both cardiovascular and non-cardiovascular causes. In women, a new diagnosis of Type 2 diabetes was associated with a sevenfold increase in mortality odds in those aged 60-74 years (OR 7.00; 95% CI 2.09, 23.47).

CONCLUSIONS

Type 2 diabetes is associated with a 2.5-fold increase in the odds of mortality in both men and women over the first 5 years from diagnosis. Our data strongly support the contention that the mortality risk associated with Type 2 diabetes essentially exists from, or may even predate, the time of diagnosis.

Risk of stroke in people with type 2 diabetes in the UK: a study using the General Practice Research Database

AIMS/HYPOTHESIS

Risk estimates for stroke in patients with diabetes vary. We sought to obtain reliable risk estimates for stroke and the association with diabetes, comorbidity and lifestyle in a large cohort of type 2 diabetic patients in the UK.

MATERIALS AND METHODS

Using the General Practice Research Database, we identified all patients who had type 2 diabetes and were aged 35 to 89 years on 1 January 1992. We also identified five comparison subjects without diabetes and of the same age and sex. Hazard ratios (HRs) for stroke between January 1992 and October 1999 were calculated, and the association with age, sex, body mass index, smoking, hypertension, atrial fibrillation and duration of diabetes was investigated.

RESULTS

The absolute rate of stroke was 11.91 per 1,000 person-years (95% CI 11.41-12.43) in people with diabetes (n = 41,799) and 5.55 per 1,000 person-years (95% CI 5.40-5.70) in the comparison group (n = 202,733). The age-adjusted HR for stroke in type 2 diabetic compared with non-diabetic subjects was 2.19 (95% CI 2.09-2.32) overall, 2.08 (95% CI 1.94-2.24) in men and 2.32 (95% CI 2.16-2.49) in women. The increase in risk attributable to diabetes was highest among young women (HR 8.18; 95% CI 4.31-15.51) and decreased with age. No investigated comorbidity or lifestyle characteristic emerged as a major contributor to risk of stroke.

CONCLUSIONS/INTERPRETATION

This study provides risk estimates for stroke for an unselected population from UK general practice. Patients with type 2 diabetes were at an increased risk of stroke, which decreased with age and was higher in women. Additional risk factors for stroke in type 2 diabetic patients included duration of diabetes, smoking, obesity, atrial fibrillation and hypertension.

OBRA 1987 and the quality of nursing home care

Because minimum government standards for quality regulate only part of the market failure, they may have unintended effects. We present a general theory of how government regulation of quality of care may affect different market segments, and test the hypotheses for the nursing home market. OBRA 1987 was a sweeping government reform to improve the quality of nursing home care. We study how the effect of OBRA on the quality of nursing home care, measured by resident outcomes, varied with nursing home profitability. Using a semi-parametric method to control for the endogenous effects of regulation, we found that this landmark legislation had a negative effect on the quality of care in less profitable nursing homes, but improved the quality in more profitable nursing homes during the initial period after OBRA. But, this legislation had no statistically significant effect in the later period when the regulation was weakly enforced.

Mortality in people with type 2 diabetes in the UK

AIMS

Under-reporting of diabetes on death certificates contributes to the unreliable estimates of mortality as a result of diabetes. The influence of obesity on mortality in Type 2 diabetes is not well documented. We aimed to study mortality from diabetes and the influence of obesity on mortality in Type 2 diabetes in a large cohort selected from the General Practice Research Database (GPRD). Methods A cohort of 44 230 patients aged 35-89 years in 1992 with Type 2 diabetes was identified. A comparison group matched by year of birth and sex with no record of diabetes at any time was identified (219 797). Hazards ratios (HRs) for all-cause mortality during the period January 1992 to October 1999 were calculated using the Cox Proportional Hazards Model. The effects of body mass index (BMI), smoking and duration of diabetes on all-cause mortality amongst people with diabetes was assessed (n = 28 725). Results The HR for all-cause mortality in Type 2 diabetes compared with no diabetes was 1.93 (95% CI 1.89-1.97), in men 1.77 (1.72-1.83) and in women 2.13 (2.06-2.20). The HR decreased with increasing age. In the multivariate analysis in diabetes only, the HR for all-cause mortality amongst smokers was 1.50 (1.41-1.61). Using BMI 20-24 kg/m(2) as the reference range, for those with a BMI 35-54 kg/m(2) the HR was 1.43 (1.28-1.59) and for those with a BMI 15-19 kg/m(2) the HR was 1.38 (1.18-1.61).

CONCLUSIONS

Patients with Type 2 diabetes have almost double the mortality rate compared with those without. The relative risk decreases with age. In people with Type 2 diabetes, obesity and smoking both contribute to the risk of all-cause mortality, supporting doctrines to stop smoking and lose weight.

Reporting of diabetes on death certificates using data from the UK Prospective Diabetes Study

AIMS

To study the effect of age at death, sex, ethnic group, date of death, underlying cause of death and social class on the frequency of reporting diabetes on death certificates in known cases of diabetes.

METHODS

Data were extracted from certificates recording 981 deaths which occurred between 1985 and 1999 in people aged 45 years or more who participated in the UK Prospective Diabetes Study, to which 23 English, Scottish and Northern Ireland centres contributed. Diabetes (9th revision of the International Classification of Diseases; ICD-9 250) entered on parts 1A-1C or 2A-2C of the death certificate was considered as reporting diabetes. Logistic regression analyses were used to determine independent factors associated with the reporting of diabetes.

RESULTS

Diabetes was reported on 42% (419/981) of all death certificates and on 46% (249/546) of those with underlying cardiovascular disease causes. Reporting of diabetes was independently associated on all death certificates with per year of age increase (OR 1.02; 95% CI 1.001-1.04, P = 0.037), underlying cause of death (non-cardiovascular causes OR 0.76; 95% CI 0.59-0.98, P = 0.035) and social class (classes I-II OR 1.00; class III OR 1.35; 95% CI 0.96-1.89, P = 0.084, classes IV-V OR 1.48; 95% CI 1.05-2.10, P = 0.027). Stratification by age, sex, and underlying cause of death also revealed significant differences in the frequency of reporting diabetes over time.

CONCLUSIONS

The rate of reporting of diabetes on cardiovascular disease death certificates remains poor. This may indicate a lack of awareness of the importance of diabetes as a risk factor for cardiovascular disease.

Gender differences in healthcare utilization and medical indicators among patients with diabetes

OBJECTIVE

To describe differences in healthcare utilization and health indicators of patients with diabetes, according to gender.

STUDY DESIGN

A population-based outcome study conducted on 21,277 diabetic patients between the ages of 45 and 64 years who are members of the second largest health maintenance organization in Israel.

METHODS

Data on healthcare utilization (process indicators) and health problems (outcome indicators) were obtained from computerized medical records that are stored routinely by the organization. The study period was the year 2002.

RESULTS

Significantly (P < 0.05) lower healthcare utilization was observed in men compared with women for all indicators examined (number of visits to physicians and the performance of urine, lipids and creatinine tests). Nonetheless, men showed better health outcomes (lower low-density lipoprotein cholesterol, triglycerides, HbA1c).

CONCLUSIONS

Women who suffer from diabetes use more healthcare services and have a higher morbidity rate compared with men. Future research should seek to identify the factors contributing to this observation, which can potentially make an important contribution to the development of disease management strategies that target diabetic women.

Hidden diabetes in the UK: use of capture-recapture methods to estimate total prevalence of diabetes mellitus in an urban population

An early requirement of the UK's Diabetes National Service Framework is enumeration of the total affected population. Existing estimates tend to be based on incomplete lists. In a study conducted over one year in North Liverpool, we compared crude prevalence rates for type 1 and type 2 diabetes with estimates obtained by capture-recapture (CR) analysis of multiple incomplete patient lists, to assess the extent of unascertained but diagnosed cases. Patient databases were constructed from six sources-a hospital diabetes centre; general practitioner registers; hospital admissions with a diagnosis of diabetes; a hospital diabetic retinal clinic; a research list of patients with diabetes admitted with stroke; and a local children's hospital. Log linear modelling was used to estimate missing cases, hence total prevalence. The crude prevalence of diabetes was 1.5% (95% confidence interval [CI] 1.41, 1.52), compared with a CR-adjusted rate of 3.1% (CI 3.03, 3.19). Age-banded CR-adjusted prevalence was always higher in males than in females and the difference became more pronounced with increasing age. Among males, CR-adjusted prevalence rose from 0.4% at age 10-19 years to 18.3% at 80+ years; in females the corresponding figures were 0.4% and 9.3%. The gap between crude and CR-estimated prevalence points to a rate of 'hidden diabetes' that has substantial implications for future diabetes care.

A comparative evaluation of digital imaging, retinal photography and optometrist examination in screening for diabetic retinopathy

AIMS

To compare the respective performances of digital retinal imaging, fundus photography and slit-lamp biomicroscopy performed by trained optometrists, in screening for diabetic retinopathy. To assess the potential contribution of automated digital image analysis to a screening programme.

METHODS

A group of 586 patients recruited from a diabetic clinic underwent three or four mydriatic screening methods for retinal examination. The respective performances of digital imaging (n=586; graded manually), colour slides (n=586; graded manually), and slit-lamp examination by specially trained optometrists (n=485), were evaluated against a reference standard of slit-lamp biomicroscopy by ophthalmologists with a special interest in medical retina. The performance of automated grading of the digital images by computer was also assessed.

RESULTS

Slit-lamp examination by optometrists for referable diabetic retinopathy achieved a sensitivity of 73% (52-88) and a specificity of 90% (87-93). Using two-field imaging, manual grading of red-free digital images achieved a sensitivity of 93% (82-98) and a specificity of 87% (84-90), and for colour slides, a sensitivity of 96% (87-100) and a specificity of 89% (86-91). Almost identical results were achieved for both methods with single macular field imaging. Digital imaging had a lower technical failure rate (4.4% of patients) than colour slide photography (11.9%). Applying an automated grading protocol to the digital images detected any retinopathy, with a sensitivity of 83% (77-89) and a specificity of 71% (66-75) and diabetic macular oedema with a sensitivity of 76% (53-92) and a specificity of 85% (82-88).

CONCLUSIONS

Both manual grading methods produced similar results whether using a one- or two-field protocol. Technical failures rates, and hence need for recall, were lower with digital imaging. One-field grading of fundus photographs appeared to be as effective as two-field. The optometrists achieved the lowest sensitivities but reported no technical failures. Automated grading of retinal images can improve efficiency of resource utilization in diabetic retinopathy screening.

Hidden diabetes in the UK: use of capture-recapture methods to estimate total prevalence of diabetes mellitus in an urban population

An early requirement of the UK's Diabetes National Service Framework is enumeration of the total affected population. Existing estimates tend to be based on incomplete lists. In a study conducted over one year in North Liverpool, we compared crude prevalence rates for type 1 and type 2 diabetes with estimates obtained by capture-recapture (CR) analysis of multiple incomplete patient lists, to assess the extent of unascertained but diagnosed cases. Patient databases were constructed from six sources-a hospital diabetes centre; general practitioner registers; hospital admissions with a diagnosis of diabetes; a hospital diabetic retinal clinic; a research list of patients with diabetes admitted with stroke; and a local children's hospital. Log linear modelling was used to estimate missing cases, hence total prevalence. The crude prevalence of diabetes was 1.5% (95% confidence interval [CI] 1.41, 1.52), compared with a CR-adjusted rate of 3.1% (CI 3.03, 3.19). Age-banded CR-adjusted prevalence was always higher in males than in females and the difference became more pronounced with increasing age. Among males, CR-adjusted prevalence rose from 0.4% at age 10-19 years to 18.3% at 80+ years; in females the corresponding figures were 0.4% and 9.3%. The gap between crude and CR-estimated prevalence points to a rate of 'hidden diabetes' that has substantial implications for future diabetes care.

Mortality from heart disease in a cohort of 23,000 patients with insulin-treated diabetes

AIMS/HYPOTHESIS

Although ischaemic heart disease is the predominant cause of mortality in older people with diabetes, age-specific mortality rates have not been published for patients with Type 1 diabetes. The Diabetes UK cohort, essentially one of patients with Type 1 diabetes, now has sufficient follow-up to report all heart disease, and specifically ischaemic heart disease, mortality rates by age.

METHODS

A cohort of 23,751 patients with insulin-treated diabetes, diagnosed under the age of 30 years and from throughout the United Kingdom, was identified during the period 1972 to 1993 and followed for mortality until December 2000. Age- and sex-specific heart disease mortality rates and standardised mortality ratios were calculated.

RESULTS

There were 1437 deaths during the follow-up, 536 from cardiovascular disease, and of those, 369 from ischaemic heart disease. At all ages the ischaemic heart disease mortality rates in the cohort were higher than in the general population. Mortality rates within the cohort were similar for men and women under the age of 40. The standardised mortality ratios were higher in women than men at all ages, and in women were 44.8 (95%CI 20.5-85.0) at ages 20-29 and 41.6 (26.7-61.9) at ages 30-39.

CONCLUSIONS/INTERPRETATION

The risk of mortality from ischaemic heart disease is exceptionally high in young adult women with Type 1 diabetes, with rates similar to those in men with Type 1 diabetes under the age of 40. These observations emphasise the need to identify and treat coronary risk factors in these young patients.

The challenge of poorly controlled diabetes mellitus

Diabetes is a growing healthcare challenge worldwide, with significant socioeconomic implications in industrialised and developing nations. Epidemiological studies indicate that diabetes is likely to reach epidemic proportions within the next few decades. A considerable proportion of people either have impaired glucose tolerance with a significant risk of development of diabetes, or have undiagnosed Type 2 diabetes. Many are poorly controlled on existing therapies, with significant implications for patients' quality of life and for healthcare expenditure. Pivotal to reducing the risk of morbidity and the development of complications and mortality is the normalisation of both fasting and postprandial blood glucose levels. Various healthcare initiatives address the attainment of this treatment goal; however, there is still a need for better disease management in both Type 1 and Type 2 diabetes.

Mortality from site-specific malignancies in type 2 diabetic patients from Verona

OBJECTIVE

The aim of the present work was to compare mortality from site-specific malignancies in type 2 diabetic patients with those in the general population.

RESEARCH DESIGN AND METHODS

Mortality from site-specific cancers was assessed in a population-based cohort of 7,148 type 2 diabetic patients from Verona (Northern Italy) during a 10-year follow-up (1987-1996) by reviewing death certificates. Standardized mortality ratio (SMR) data were computed using as reference mortality rates in the general population of Verona.

RESULTS

During follow-up, 641 patients (378 men and 263 women) died of malignancies. The most common causes of death among site-specific malignancies were digestive tumors both in men (140 of 378, 37.0%) and women (105 of 263, 39.9%), respiratory tumors in men (103 of 378, 27.2%), and tumors of the reproductive system in women (79 of 263, 30.0%). A slight increase in the overall mortality from malignancies was observed in diabetic patients and achieved statistical significance in women (observed/expected = 1.16, 95% CI 1.02-1.30; P = 0.019) but not in men (observed/expected = 1.07, 0.97-1.19; P = 0.163). Excess mortality from hepatic cancer (SMR = 1.86, 1.44-2.38) was observed in both men and women. In addition, women with diabetes experienced a higher mortality from pancreatic tumors (observed/expected = 1.78, 1.13-2.67) and breast tumors (observed/expected = 1.40, 1.06-1.81). Excess mortality from breast cancer was confined to obese women with diabetes.

CONCLUSIONS

Mortality from site-specific malignancies is different in type 2 diabetic patients than in the general population. Better control of body weight seems necessary to prevent the excess mortality from breast cancer in women.

Long-term risk of malignant neoplasm associated with gestational glucose intolerance

BACKGROUND

Previous studies have demonstrated an association between diabetes mellitus and cancer risk. However to the author's knowledge, no data regarding the risk of cancer associated with subclinical impaired glucose tolerance have been published to date. An association between various types of cancer and any continuum of risk across the spectrum of glucose tolerance may be important in determining the nature of the association between diabetes mellitus and the risk of malignancy.

METHODS

The current study was conducted to examine the long-term risk of malignant neoplasms associated with maternal glucose intolerance. A 20-year follow-up study of a cohort of women who had previously taken part in a study in 1980 that investigated maternal glucose metabolism and fetal outcome was performed. Gestational glucose metabolism, smoking behavior, and weight and height measured at the time of index pregnancy, as well as weight, height, and smoking behavior assessed by questionnaire in 1999, were examined. The main endpoint of the study was hospital admission with a diagnosis of malignant neoplasm as ascertained by linkage data.

RESULTS

Thirty-four of the 753 women living in Grampian (4.5%) were admitted to the hospital with a diagnosis of malignant neoplasm; of these, 18 cases were malignant neoplasms of the breast. After adjustment for known risk factors, both malignant neoplasm and malignant neoplasm of the breast were found to be significantly associated with gestational glucose intolerance.

CONCLUSIONS

Subclinical glucose intolerance during pregnancy was found to be associated with a dose-related increase in the risk of malignant neoplasm, particularly malignant neoplasm of the breast.

Diabetes-related morbidity and mortality in a national sample of U.S. elders

OBJECTIVE

Although the number of elders with diabetes has increased dramatically, there are few data on rates of mortality and serious complications in older populations with diabetes. To determine such rates, we conducted a population-based, nonconcurrent cohort study using claims data from the 1994-1996 Medicare 5% Standard Analytical File.

RESEARCH DESIGN AND METHODS

Codes from the ICD-9 were used to identify diabetes and the following complications: amputation, lower extremity infection, gangrene, blindness, acute myocardial infarction, ischemic heart disease, stroke, and metabolic disorders. Using these codes, we assembled a cohort of 148,562 Medicare Part A and B beneficiaries who were > or = 65 years of age, who were alive on 1 January 1995, who were not in managed care in 1994, and who had a diabetes-related claim in 1994. Age-specific rates of death and complications were then calculated.

RESULTS

During 24 months of follow-up, 22,044 (14.8%) elders with diabetes died. Death rates in men and women increased significantly with age. Compared with their counterparts in the general U.S. population, elders with diabetes suffered excess mortality at every age group, corresponding to an overall standardized mortality ratio of 1.41 (95% CI 1.39,1.43). The incidence of ischemic heart disease and stroke was 181.5 and 126.2 per 1,000 person-years, respectively, which was higher than the incidence of all other diabetes-related complications.

CONCLUSIONS

In every age group, elders with diabetes have significantly higher all-cause mortality rates than the general population. Medicare data may be useful in monitoring trends in diabetes-related morbidity and total mortality in U.S. elders with diabetes.

Incidence, prevalence, and mortality of insulin-dependent (type 1) diabetes mellitus in Lithuanian children during 1983-98

AIMS/HYPOTHESIS

Our purpose is to analyze interrelations of the incidence, prevalence and mortality of childhood-onset insulin-dependent diabetes mellitus (type 1) in Lithuania.

METHODS

Incidence and prevalence rates were based on the national type 1 diabetes register during 1983-98. The cohort study was performed to evaluate the standardized mortality ratios.

RESULTS

The average incidence of type 1 diabetes during the 16-yr study period was 7.36 per 100,000/yr. For both males and females the highest incidence of type 1 diabetes was recorded in the 10-14 yr age group. The regression-based linear trends of the increase in incidence in various age groups and the annual percentage change for both genders was 2.05 (p = 0.0039) and the greatest regression slope is observed for both genders in the 10-14 yr age group. Regression-based linear trends in type 1 diabetes prevalence indicate an even growth in all age groups (3.47; p = 0.001), although the annual percentage change is most prominent in the 5-9 yr age group for girls (4.95%/yr) and in the 10-14 yr age group for boys (4.06%/yr). The standardized mortality ratio of all-cause mortality in people with diabetes is higher than in the common population 7.71 (p < 0.0001). The standard mortality ratio for all causes increases with longer diabetes duration.

CONCLUSION/INTERPRETATION

The significant increasing trend of incidence and prevalence during 1983-98 is observed. The annual percentage change is similar. The young patients with type 1 diabetes have a higher mortality risk.

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.

Predictors of mortality from type 2 diabetes mellitus in Canterbury, New Zealand; a ten-year cohort study

The aim was to establish mortality rates in a cohort of subjects with type 2 diabetes mellitus over 10 years in Canterbury, New Zealand (NZ) and to determine baseline prognostic factors. Subjects (447) with type 2 diabetes (208 male, 239 female; age range 30-82 years, median 62 years; of predominantly European origin) were characterised in a clinic survey in 1989. Individual status (dead or alive) at June 1 1999 (10 year follow-up) was ascertained. Mortality rates were compared with the general NZ population and the relative risk (RR) of baseline prognostic factors evaluated with Cox's proportional hazards model. At 10 years, 232 subjects were confirmed as alive and 187 as dead - only 28 were untraceable. Ten year survival was 55% (95% CI: 50-60) for the cohort, compared with 70% (95% CI: 65-75) at 6 years. Factors assessed at baseline (1989), that were independently prognostic of total mortality, included age (RR 2.0, 95% CI: 1.6-2.5), pre-existing coronary artery disease (CAD; RR 1.7, 95% CI: 1.2-2.4) and albuminuria (RR 1.58, 95% CI: 1.1-2.3). Glycated haemoglobin was not a significant predictor of total mortality, although was a predictor of CAD mortality in those subjects free of CAD in 1989 (RR 1.6, 95% CI: 1.1-2.3). In the latter subset, independent prognostic factors for CAD mortality also included age (RR 2.5, 95% CI: 1.7-3.8), hypertension (RR 1.9, 95% CI: 1.0-3.7), peripheral vascular disease (RR 2.4, 95% CI: 1.3-4.5) and smoking (RR 2.6, 95% CI: 1.2-5.8). Increased mortality in type 2 diabetic subjects is therefore attributable to multiple risk factors. Improved outcomes will depend on interventions targeted at glycaemic and all other remediable factors.

Excess mortality in a population with diabetes and the impact of material deprivation: longitudinal, population based study

OBJECTIVES

To establish the age and sex specific mortality for people with diabetes in comparison with local and national background populations; to investigate the relationship between mortality and material deprivation in an unselected population with diabetes.

DESIGN

Longitudinal study, using a population based district diabetes register.

SETTING

South Tees, United Kingdom.

PARTICIPANTS

All people known to have diabetes living in Middlesbrough and Redcar and Cleveland local authorities on 1 January 1994.

MAIN OUTCOME MEASURE

Death, from any cause, between 1 January 1994 and 31 December 1999.

RESULTS

Over the six years of the study 1205 (24.9%) of 4842 participants died. All cause standardised mortality ratios for type 1 diabetes were 641 (95% confidence interval 406 to 962) in women and 294 (200 to 418) in men, and those for type 2 diabetes were 160 (147 to 174) in women and 141 (130 to 152) in men. Cause specific standardised mortality ratios were increased for ischaemic heart disease, cerebrovascular disease, and renal disease; no reductions in mortality from other causes were seen. The risk of premature death increased significantly with increasing material deprivation (P<0.001).

CONCLUSIONS

Diabetes is associated with excess mortality, even in an area with high background death rates from cardiovascular disease. This excess mortality is evident in all age groups, most pronounced in young people with type 1 diabetes, and exacerbated by material deprivation. Aggressive approaches to the management of cardiovascular risk factors could reduce the excess mortality in people with diabetes.

Automated detection of microaneurysms in digital red-free photographs: a diabetic retinopathy screening tool

AIMS

To develop a technique to detect microaneurysms automatically in 50 degrees digital red-free fundus photographs and evaluate its performance as a tool for screening diabetic patients for retinopathy.

METHODS

Candidate microaneurysms are extracted, after the image has been modified to remove variations in background intensity, by algorithms that enhance small round features. Each microaneurysm candidate is then classified according to its intensity and size by the application of a set of rules derived from a training set of 102 images.

RESULTS

When 3,783 individual images were analysed and the results compared with the opinion of a clinical research fellow examining the same images, the program achieved a sensitivity of 81% and a specificity of 93% for the detection of images containing microaneurysms. Nine hundred and twenty-five sets of 4 images per patient were then analysed and the total number of microaneurysms detected compared with the overall patient retinopathy grade derived by the clinician examining the same images. In this context, intended to mimic a screening situation, the program achieved a sensitivity of 85% and a specificity of 76% for the detection of patients with (any) retinopathy (positive predictive value 0.71, negative predictive value 0.88).

CONCLUSIONS

An automated technique was developed to detect retinopathy in digital red-free fundus images that can form part of a diabetic retinopathy screening programme. It is believed that it can perform a useful role in this context identifying images worthy of closer inspection or eliminating 50% or more of the screening population who have no retinopathy.

Non-dipping circadian blood pressure and renal impairment are associated with increased mortality in diabetes mellitus

AIMS

To assess the relevance of circadian blood pressure variation to future morbidity and mortality in patients with diabetes mellitus.

METHODS

A retrospective descriptive 4 year follow-up study of data collected after ambulatory blood pressure monitoring in a clinic setting.

RESULTS

Seventy-five patients (46 male; 29 female) of whom 41 % had Type 1 diabetes and 59% Type 2 were followed up for a median of 42 months (11-56). The median creatinine for the whole group at baseline was 101 (56-501) micromol/l. The median circadian blood pressures for the total study population were 147 (110-194)/87 (66-109) mmHg during daytime and 132 (86-190)/77 (50-122) mmHg during night-time. Half of the patients exhibited a fall in night-time pressures to 10% lower than daytime pressures (dippers). Dippers were younger, 47 (32-75) years, than non-dippers, 57 (35-79) years, P = 0.03. Over time, dippers had a lower mortality than non-dippers, with 8% deaths in the cohort of dippers, 26% deaths in the cohort of non-dippers, P = 0.04. Cox regression analysis revealed significant contributions from age, duration of diabetes and baseline renal function to subsequent mortality in non-dippers. Analysing current degree of renal impairment and original dipper status together revealed that, of those patients whose creatinine remained normal, 7% of patients whose blood pressure dipped had subsequently died and 10% of non-dipping patients had died; of those patients whose creatinine unequivocally rose, 10% of dipping patients had died and 42% of non-dipping patients had died, P = 0.03

CONCLUSIONS

Loss of circadian variation in blood pressure is associated with an increased mortality rate, regardless of diabetes type. The combination of non-dipping and subsequent renal impairment leads to the highest mortality rate. The study suggests a role for ambulatory blood pressure monitoring in day-to-day clinical practice to select patients with nephropathy who are at greatest risk, in an effort to alter outcome.

Showing neuropathy is related to increased mortality in diabetic patients - a survival analysis using an accelerated failure time model

Diabetic subjects still have a reduced life expectancy despite many potential advances in patient care. Furthermore, population-based studies in well-defined cohorts of patients, to investigate the reduced life expectancies, are generally lacking. Computerized baseline data on a cohort of diabetic patients first attending our clinic during 1982-1985 were used to identify risk factors for increased mortality. This was carried out using an accelerated failure time (ACF) model. Out of 794 patients entered into the model, 201 (25.3%) patients died between 1982 and 1995. Baseline microvascular diabetic complications (peripheral sensory neuropathy and nephropathy) were found to be associated with increased mortality in patients, indicating that these are important, often overlooked, markers for those at greatest risk. Patients with type I (insulin dependent) diabetes mellitus were also identified as being at greater risk.

The epidemiology of Type 2 diabetes and its current measurement

Type 2 diabetes is globally increasing in prevalence and is widely recognized as a major cause of morbidity and mortality, as well as being a burden to the health-care services. Planning for current and future diabetes services requires up-to-date prevalence information. The enumeration of Type 2 diabetes is, however, surprisingly difficult. Large numbers of people are undiagnosed, and those known cases have variable loci of care. Traditional techniques include cross-sectional diagnostic surveys, postal or house-to-house surveys and cohort surveys. All are time-consuming and expensive, and may potentially undercount. The use of multiple patient lists (e.g. hospital clinic data, general practitioner (GP) lists, prescribing information, etc.) can, however, increase accuracy and, if the data are computerized, may be rapid and inexpensive. A new and potentially exciting tool to utilize multiple lists in Type 2 diabetes prevalence assessment is known as 'capture-recapture'. In this, statistical models are used to estimate prevalence from the degree of overlap between lists. Capture-recapture is emerging as a valuable tool in the epidemiological assessment of Type 2 diabetes.

The British Diabetic Association Cohort Study, I: all-cause mortality in patients with insulin-treated diabetes mellitus

AIMS

To assess mortality in patients with diabetes incident under the age of 30 years.

METHODS

A cohort of 23 752 diabetic patients diagnosed under the age of 30 years from throughout the United Kingdom was identified during 1972-93 and followed up to February 1997. Following notification of deaths during this period, age- and sex-specific mortality rates, attributable risks and standardized mortality rates were calculated.

RESULTS

The 23 752 patients contributed a total of 317 522 person-years of follow-up, an average of 13.4 years per subject. During follow-up 949 deaths occurred in patients between the ages of 1 and 84 years, 566 in males and 383 in females. All-cause mortality rates in the patients with diabetes exceeded those in the general population at all ages and within the cohort were higher for males than females at all ages except between 5 and 15 years. The relative risk of death (standardized mortality ratio, SMR), was higher for females than males at all ages, being 4.0 (95% CI 3.6-4.4) for females and 2.7 (2.5-2.9) for males overall, but reaching a peak of 5.7 (4.7-7.0) in females aged 20-29, and of 4.0 (3.1-5.0) in males aged 40-49. Attributable risks, or the excess deaths in persons with diabetes compared with the general population, increased with age in both sexes.

CONCLUSIONS

This is the first study from the UK of young patients diagnosed with diabetes that is large enough to calculate detailed age-specific mortality rates. This study provides a baseline for further studies of mortality and change in mortality within the United Kingdom.

The British Diabetic Association Cohort Study, II: cause-specific mortality in patients with insulin-treated diabetes mellitus

AIMS

To measure cause-specific mortality, by age, in patients with insulin-treated diabetes incident at a young age.

METHODS

A cohort of 23 752 patients with insulin-treated diabetes diagnosed under the age of 30 years, from throughout the United Kingdom, was identified during 1972-93 and followed to February 1997. Death certificates have been obtained for deaths during the follow-up period and cause-specific mortality rates and standardized mortality ratios by age and sex are reported.

RESULTS

During the follow-up period 949 deaths occurred and at all ages mortality rates were considerably higher than in the general population. Acute metabolic complications of diabetes were the greatest single cause of excess death under the age of 30 years. Cardiovascular disease was responsible for the greatest proportion of the deaths from the age of 30 years onwards.

CONCLUSIONS

Deaths in patients with diabetes diagnosed under the age of 30 have been reported and comparisons drawn with mortality in the general population. To reduce these deaths attention must be paid both to the prevention of acute metabolic deaths and the early detection and treatment of cardiovascular disease and associated risk factors.

Causes of death and associated factors among patients with non-insulin-dependent diabetes mellitus in Taipei, Taiwan

A cohort of 766 patients with non-insulin-dependent diabetes mellitus (NIDDM) from a general teaching hospital in Taipei, Taiwan were followed prospectively to assess survival experience and associated risk factors. Data were abstracted from the medical records and additional information was obtained from patients or their closest relatives using a structured questionnaire. Date and cause of death were determined from death certificates. Standardized mortality ratios were calculated by the direct method. Chi2-Square test and Cox's proportional hazard analysis were used to control for potential confounders. During a median follow-up of 3.5 years (range 1 month to 4.6 years), 131 deaths occurred. Of these, 29.8% were due to cardiopulmonary disease (ICD 401-429), 13.0% due to cerebrovascular disease (ICD 430-438), 13.0% due to acute diabetes metabolic complications (250.1, 250.2), and 11.4% due to nephropathy (580-589). Adjusted for age, people with NIDDM had 2.2 (95% CI 1.6-2.9) times the risk of death than members of the general population, and cause-specific standardized mortality ratios were: CPD 4.6, nephropathy 8.8, cerebrovascular disease 1.9, and neoplasm 0.7. Age, fasting plasma glucose, hypertension, and proteinuria were positively and independently associated with all-cause mortality (P < 0.05 for each). Thus, NIDDM patients have higher mortality rates than the general population in Taiwan, and age, fasting plasma glucose, hypertension, and proteinuria are associated with this excess risk. Proper application of available interventions may control these factors with a consequent reduction in mortality. Particular attention is needed to prevent deaths from the acute metabolic complications of diabetes.

Mortality in a large population-based cohort of patients with drug-treated diabetes mellitus

OBJECTIVES

This paper presents detailed cause-specific data about excess mortality among diabetic persons in Finland, by age and sex.

METHODS

Five-year follow-up data on the Finnish population aged 30 through 74 years were analyzed. During these 5 years, 11,215 persons with diabetes and 102,843 persons without diabetes died. The diabetic population was defined as people who were entitled to free medication for diabetes at the beginning of the follow-up period, that is, at the end of 1980.

RESULTS

The relative mortality of persons with drug-treated diabetes compared with nondiabetic persons was higher among women (3.4) than among men (2.4). Almost three quarters of the mortality excess was due to circulatory diseases. For most other causes of death, too, diabetic persons had higher than average mortality. The exceptions were lung cancer, chronic obstructive pulmonary disease, and alcohol poisoning.

CONCLUSIONS

Diabetes is a general risk factor for untimely death and makes a significant contribution to overall national death rates, particularly for circulatory diseases. Lower than average mortality from smoking-related diseases and alcohol poisoning, however, warrant optimism about the effects of health education among diabetic persons.

Impacts of components of the metabolic syndrome on health status and survival in an aged population

The clinical significances of different components of the multiple metabolic syndrome were studied in a five-year follow-up study of random persons (n = 1,199) of four birth cohorts at ages 65, 75, 80, and 85 years. The subjects were examined clinically and their serum lipids, blood glucose, plasma insulin, blood pressure, and health score were determined. The health score was measured using a visual analogue scale. All subjects were followed for 5 years. Health score, diastolic blood pressure and body mass index declined over age, but serum triglycerides, and blood glucose were similar, whilst serum high density lipoprotein (HDL)-cholesterol increased. Among women fasting plasma insulin was lowest in the age group of 65 years. The associations of components of the multiple metabolic syndrome varied by age. In the age groups of 65 and 75 years high body mass index, plasma insulin, glucose, triglycerides and low HDL-cholesterol were associated with impaired health. In the age group of 85 years high blood pressure, total cholesterol, and HDL-cholesterol were associated with good health. The baseline health score was consistently lower in the decedents than survivors of all age groups, but components of the metabolic syndrome were generally not associated with impaired survival.

Over-mortality as related to age and gender in patients with established non-insulin-dependent diabetes mellitus

In 1981-1982, 5699 persons representing 92.9% of the total population aged 60-74 years living in Fredericia, Denmark, were interviewed about a possible history of diabetes and had a fasting blood glucose measured. A total of 236 gave a positive history of diabetes; 88 had one fasting blood glucose of 7 mmol/L or more. For each of these probands, an age- and gender-matched control person with normal fasting blood glucose and no history of diabetes was selected randomly. Of the 236, 91.5% had NIDDM as judged by glucagon-stimulated C-peptide tests. At the end of December 1995, the participants were traced through the National Register and their status (alive or dead) was determined. The date of death was confirmed. The median observation time from screening and inclusion in the study till death or the end of the observation period in December 1995 was 12.81 years, the maximum was 14.91, and the 25th and 75th percentile values were 6.36 and 13.94 years, respectively. At the end of 1995, 165 (74.4%) of 228 persons with known diabetes at the time of ascertainment had died opposed to 90 (40.4%) of the 223 nondiabetic control persons. The difference is statistically highly significant (p < 0.00001, log-rank test). Within the first 5 years of observation, 42.9% of diabetic men died and only 22.5% of non-diabetic men. This percentage of deaths in diabetic men was found already in the 60-64 year age interval (46.2%). The mortality rate for the non-diabetic population seems to increase later. After 13 years of observation, 74 (81.3%) of 91 men with known diabetes had died, in the age-matched control men, 50 (56.2%) of 89 (p = 0.00006). Ninety-one (66.4%) of 137 diabetic women had died: 40 (29.9%) of 134 control women (p < 0.00001). The difference between mortality in diabetic men and women, and between nondiabetic men and women is highly significant (p = 0.00285 and 0.00001, respectively). The over-mortality of established diabetic persons decreases with age. In the age group 60-74 years, the over-mortality is about 2.5 without gender difference.

The impact of gender and general risk factors on the occurrence of atherosclerotic vascular disease in non-insulin-dependent diabetes mellitus

While it is generally accepted that non-insulin-dependent diabetes mellitus (NIDDM) increases atherosclerotic risk, controversy remains as to whether this effect is greater for women than men (thus reducing the usual gender differential). Furthermore, it is unclear to what extent changes in general risk factors may account for this increased risk. The literature was reviewed with meta-analyses. Gender specific overall relative risks with 95% confidence intervals for coronary heart disease (CHD) mortality (ICD codes 410-414) were calculated. Similarly, overall gender specific odds ratios for prevalent myocardial infarction (MI) are presented. Data are generated from both fixed effects and random effects models. Frequency counts of studies showing specific cardiovascular disease (CVD) risk factor effects in diabetes are given as is the number of studies showing diabetes to be an independent risk factor. The overall relative risk (the ratio of men to women) for CHD mortality in diabetes was 1.46 (1.21-1.75) and 2.29 (2.05-2.55) in nondiabetes suggesting that the gender differential is reduced in diabetes. However, heterogeneity was high (P < 0.001). Exclusion of studies that were exclusively in elderly subjects eliminated heterogeneity (P > 0.05), but retained a separation of the confidence intervals. Overall odds ratios (men:women) show no suggestion of a diabetes effect on the gender difference for prevalent MI, 1.77 (diabetes) and 1.79 (no diabetes). The effects of six general CVD risk factors were unclear, although the largest study showed a clear effect of cholesterol, smoking, and blood pressure. All 10 studies in women report diabetes to be an independent risk factor as do 8 out of 12 studies in men. NIDDM reduces the gender differential in CHD mortality, but not for prevalent MI (or other end points). Although the effect of specific CVD risk factors is inconsistent across studies, this is likely to reflect limited sample size and power. The major three risk factors, cholesterol, blood pressure, and smoking, probably operate in NIDDM but do not fully explain the increased risk of CVD in NIDDM.

Cardiovascular mortality and morbidity in type-2 diabetes mellitus

A representative number of prospective studies clearly indicate that cardiovascular morbidity and mortality is significantly increased in type-2 diabetic patients in comparison with non-diabetic control subjects. The cardiovascular death rate is 4.4 fold increased in those diabetic patients presenting none of the classical risk factors (hypertension, hypercholesterinemia or smoking) compared with age-matched control subjects (MRFIT). A decreased survival rate after myocardial infarction, congestive heart failure and an increased occurrence of silent ischemia are responsible for the poor prognosis of type-2 diabetic patients. Recent studies indicate that haemostatic abnormalities and endothelial dysfunction are important risk factors for coronary events in diabetic as well as in nondiabetic patients. In newly diagnosed type-2 diabetic patients a similar prevalence of myocardial infarction and angina compared to previously known type-2 diabetes was found. The long prediabetic period and clustering of risk factors may be very relevant for the high prevalence of cardiovascular disease already at diagnosis of type-2 diabetes. More recent studies performed in Scotland and Verona demonstrated a mortality risk approximately only 50% higher than in nondiabetic subjects. The reduction in the mortality risk could reflect an improvement in diabetes prognosis from the 1960s to the 1980s. Recent observations in type-2 diabetic patients from Finland indicate that glycemic control is an important predictor for coronary heart disease morbidity and mortality. However incidence of coronary heart disease is only low in those patients presenting with a HbAlc value below 6.0%. More information will be available after analysis of the United Kingdom prospective diabetes study. (UKPDS).

Insulin treated diabetes mellitus: causes of death determined from record linkage of population based registers in Leicestershire, UK

STUDY OBJECTIVE

Analyses of causes of mortality in people with diabetes using data form death certificates mentioning diabetes provide unreliable estimates of mortality. Under-recording of diabetes as a cause on death certificates has been widely reported, ranging from 15-60%. Using a population based register on people with diabetes and linking data from another source is a viable alternative. Data from the Office of Population Censuses and Surveys (OPCS) are the most acceptable mortality data available for such an exercise, as direct comparison with other published mortality rates is then possible.

DESIGN

A locally maintained population-based mortality register and all insulin-treated diabetes mellitus cases notified to the Leicestershire diabetes register (n = 4680) were linked using record linkage software developed in-house (Lynx). This software has been extensively used in a maintenance and update cycle designed to maximise accuracy and minimise duplication and false registration on the diabetes register. Deaths identified were initially coded locally to the International Classification of Diseases, 9th revision (ICD9), and later a linkage was performed to use official OPCS coding. Mortality data identified by the linkage was indirectly standardised using population data for Leicestershire for 1991. Standardised mortality ratios (SMR) were estimated, with 95% confidence intervals. Insulin dependent diabetes (IDDM) was defined as diabetes diagnosed before age 30 years with insulin therapy begun within one year of diagnosis. All other types were considered non-insulin dependent diabetes (NIDDM). Analyses were performed for the whole sample and then for the NIDDM subgroup. Results from these analyses were similar and therefore only whole group analyses are presented.

MAIN RESULTS

A total of 370 deaths were identified for the period of 1990-92 inclusive - 56% were in men and 44% in women, median age (range) 71 years (12-94). Approximately 90% of deaths were subjects with NIDDM. Diabetes was mentioned on 215 (58%) death certificates. The all causes SMRs were significantly raised for men and women for all ages less than 75 years. Ischaemic heart disease (ICD9) rubrics 410-414) accounted for 146 (40%) deaths - 41% of male and 38% of female deaths. Male and female SMRs were significantly raised for the age groups 45-64, 65-74, and 75-84 years. Cerebrovascular disease (ICD9 rubrics 430-438) accounted for 39 (10%) deaths and the SMR for women the external causes of death (ICD9 rubrics E800-E999) were also significantly raised overall and in age groups 15-44 and 45-64 years. This was not true for men, although numbers of deaths in this category were small for both men (4) and women (9).

CONCLUSION

Record linkage has been used successfully to link two local, population based registers. This has enabled an analysis of mortality in people with diabetes to be performed which overcomes the problems associated with using as a sample, death certificates where diabetes is mentioned. The mortality rates and SMRs estimated should more accurately reflect the true rates than would be possible using other methods. The persisting excess mortality identified for people with diabetes is of a similar magnitude and attributable to similar causes as has been reported elsewhere in population based studies.

Wall thickening of common carotid arteries in patients affected by noninsulin-dependent diabetes mellitus: relationship to microvascular complications

This study evaluates the wall thickness of common carotid arteries and the atherosclerotic involvement of the carotid bifurcations in patients with noninsulin-dependent diabetes mellitus (NIDDM), with and without microvascular complications. Seventy subjects affected by NIDDM, and 17 healthy controls were evaluated by means of high-resolution echo-Doppler scan. Twenty-six diabetics (Group A) and complications (overnight proteinuria > 500 mg, background retinopathy, sensory neuropathy), while 44 (Group B) had no complications. The two groups were comparable for age, sex, plasma lipid profile, and smoking habit. Arterial hypertension was present in 15 of 26 (58%) complicated patients (Group A) and in 18 of 44 (41%) uncomplicated patients (Group B). None of the patients had a history of cerebrovascular disease. The authors found that the wall thickness of the common carotid artery was greater and atherosclerotic lesions of the carotid bifurcation were more frequent in diabetic patients with microvascular complications than in uncomplicated diabetics (who had a similar distribution of other risk factors for atherosclerosis) and in nondiabetic controls. These data on the one hand confirm the role of diabetes as an independent risk factor for carotid atherosclerosis and, on the other hand, indicate a correlation between microvascular lesions and early atherosclerosis in diabetes.

The Verona diabetes study: a population-based survey on known diabetes mellitus prevalence and 5-year all-cause mortality

This population-based survey aimed to determine the prevalence of known diabetes mellitus on 31 December 1986, and to assess all-cause mortality in the subsequent 5 years (1987-1991) in Verona, Italy. In the study of prevalence, 5996 patients were identified by three independent sources: family physicians, diabetes clinics, and drug prescriptions for diabetes. Mortality was assessed by matching all death certificates of Verona in 1987-1991 with the diabetic cohort. Overall diabetes prevalence was 2.61% (95% confidence interval 2.56-2.67). Prevalence of insulin-dependent and non-insulin-dependent diabetes mellitus was 0.069% (0.059-0.078) and 2.49% (2.43-2.54), respectively. Diabetes prevalence sharply increased after age 35 years up to age 75-79, and finally declined. Prevalence was higher in men up to age 69 years, in women after age 75 years. Of the diabetic cohort 1260 patients (592 men, 668 women) died by 31 December 1991, yielding an overall standardized mortality ratio of 1.46 (CI 1.38-1.54). Even though the differences narrowed with age, mortality rates in the diabetic cohort were higher than in the non-diabetic population at all ages. Women aged 65-74 years showed observed/expected ratio higher than men (2.27, CI 1.92-2.66, vs 1.50, CI 1.30-1.72), while in other age groups the sex-related differences were not significant. Pharmacological treatment of diabetes was associated with an excess mortality, while treatment with diet alone showed an apparent protective effect on mortality (observed/expected ratio 0.73, CI 0.58-0.92).(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiovascular morbidity and mortality in type 2 diabetic patients: a 22-year historical cohort study in Dutch general practice

A historical cohort study was performed to assess cardiovascular morbidity and mortality in Type 2 (non-insulin-dependent) diabetic patients. The data were collected from 1967 to 1989 in four Dutch general practices performing the Continuous Morbidity Registration Nijmegen. Each newly diagnosed Type 2 diabetic patient fulfilling the WHO criteria (n = 265) was matched to a control patient for practice, sex, age, and social class. Inclusion started in 1967, the first year of the still ongoing, Continuous Morbidity Registration Nijmegen. On average, a follow-up of 6.8 years (range 1 month-22 years) was realized. Compared to the non-diabetic control patients, the Type 2 diabetic patients showed higher cardiovascular morbidity (risk ratio 1.76, 95% CI 1.34-2.30) and a higher mortality rate (risk ratio 1.54, 95% CI 1.07-2.23). Mortality after 10 years was 36% vs 20% (p < 0.01), the median survival time 16 years vs 19 years. The cumulative survival rates were significantly different (p < 0.01) between patients and controls in the age group 65-74 years. The higher mortality in Type 2 diabetic patients was completely due to an excess of cardiovascular death (risk ratio 2.05, 95% CI 1.24-3.37).

Mortality in diabetic subjects: an eleven-year follow-up of a community-based population

In 1979, all the known diabetic subjects (849) were identified from a community (population 81851), of whom 717 (85%) were reviewed by a single observer. Using the NHS Central Register, follow-up was completed for 98% of subjects. After 11 years, 306 (42.7%) diabetic subjects had died, of whom 65 were insulin treated and 241 were non-insulin treated. Circulatory disease accounted for 168 (54.9%) deaths, of which 124 (73.8%) were due to ischaemic heart disease. The standardized mortality ratio (SMR) for all causes of death, based on data from England and Wales, was significantly raised for both insulin-treated and non-insulin-treated patients (1.75, 95% CI 1.35 to 2.24 and 1.32, 95% CI 1.15 to 1.50, respectively). SMRs for all cause mortality were significantly greater for diabetic subjects in the 45-64 (SMR, 1.97, 95% CI 1.34 to 2.80), 65-74 (SMR 1.59, 95% CI 1.27 to 1.97 and 75 years and over (SMR 1.26, 95% CI 1.08 to 1.45) age ranges. Using a proportional hazards model, after adjusting for age and gender, systolic blood pressure and vibration threshold were significant predictors of all cause mortality in insulin-treated subjects. For non-insulin-treated subjects, blood glucose, systolic blood pressure, glycated haemoglobin, retinopathy, proteinuria, coronary artery disease, and stroke were significant baseline predictors of mortality. No association was found for serum cholesterol, body mass index, diastolic pressure or cigarette smoking in either treatment group.

The mortality of elderly people with diabetes

To assess the full effect of diabetes on survival in elderly subjects, residents of Melton Mowbray aged 65, 70, 75, 80, and 85 years were screened by glucose tolerance test and followed up for 4.5 years. Death occurred in 56 of 520 normal subjects, 9 of 44 subjects with impaired glucose tolerance, 7 of 19 newly diagnosed diabetic subjects, and 27 of 52 known diabetic subjects. Diabetic subjects were 4.5 times (95% confidence interval 2.9-7.0) more likely to die than subjects with normal glucose tolerance. Thus elderly diabetic subjects have a substantially increased risk of death compared to their normal glucose tolerant peers.

Mortality and coronary heart disease in diabetes mellitus

A clinic-based study of 1,063 patients with Type 2 diabetes recruited from 1973 to 1982 identified 533 deaths (attributed to coronary heart disease in 268 cases) by 31 December 1989. When compared to the general population of Australia the overall standardised mortality ratio was 1.42 (95 per cent confidence interval (CI) 1.26 to 1.58) for females and 1.19 (CI 1.03 to 1.35) for males. Cox regression analysis showed that having coronary heart disease or absence of foot pulses at the time of entrance to the study were the major independent risk factors for overall mortality after adjustment for initial age. Elevated cholesterol and blood pressure were found to be major independent risk factors for death from coronary heart disease.

Mortality among type 2 diabetic individuals and associated risk factors: the Three City Study

The 10 year mortality experience was determined in a population-based cohort of 540 Type 2 diabetic individuals. The association between potential risk factors and all causes mortality was examined. Diabetes was not mentioned anywhere on the death certificate in 46% of 274 decedents. Diseases of the circulatory system (ICD9-390-459) accounted for the majority (62%) of deaths in this cohort. Ten-year survival was poorer than expected for both men and women compared to the age- and sex-matched Minnesota population. Standardized mortality ratios for selected causes of death indicated excess for cardiovascular disease (ICD9-390-459), coronary heart disease (ICD9 410-414) and cerebrovascular disease. Baseline variables associated with all causes of mortality included age and a history of macrovascular disease. These findings indicate that mortality data significantly underestimate the magnitude of diabetes and that individuals with diabetes have poorer survival than non-diabetic individuals.

A population-based study of the incidence of complications associated with type 2 diabetes in the elderly

One hundred and eighty-eight known Type 2 diabetic patients aged over 60 years identified by a geographically based survey of a population of 40,076 were followed for a median of 6 years to determine the incidence of various complications. There were 63 deaths and two patients were lost to follow-up. The presence of complications was determined using a structured questionnaire and clinical examination. Incidence rates of ischaemic heart disease, stroke, and peripheral vascular disease (PVD) were 56 (95% CI 41-75), 22 (13-35), and 146 (117-174) 1000-person-years-1 of follow-up, respectively. Rates of stroke and PVD rose significantly with age. Retinopathy occurred at a rate of 60 (42-83) 1000-person-years-1 and cataract at 29 (17-46) 1000-person-years-1 although visual acuity in survivors did not deteriorate overall, probably reflecting the high mortality associated with cataract. The rate of proteinuria (albumin concentration greater than 300 mg l-1) was 19 (9-34) 1000-person-years-1. Incidence rates were unrelated to sex or duration of diabetes. Diabetes is associated with a continuing incidence of complications into old age. Adequate facilities are required to assess and treat the resulting morbidity in a population with an increasing proportion of elderly people.