Effect of repeated exercise bouts on high density lipoprotein-cholesterol and its subfractions HDL2-C and HDL3-C

Nine sedentary men (mean age, 22.8 yrs) were studied during and after treadmill exercise at 65% VO2max to determine the number of repeated exercise bouts required to bring about a sustained elevation in HDL-cholesterol and its subfraction HDL2-C and HDL3-C. A Latin square counterbalanced design was used. Thirty minute exercise sessions were undertaken in the following patterns: (1) single bout, (2) two bouts on alternate days, and (3) three bouts on alternate days. The exercise bouts in patterns 2 and 3 were separated by 48 h. Patterns 1, 2 and 3 were conducted 7 days apart. Blood samples were obtained prior to each pattern and at 5 min, 24 and 48 h after the last session within each pattern. There were no significant differences in triglycerides and total cholesterol between the selected blood sampling points for all patterns. Total HDL-C remained higher (p < 0.05) than the pre-exercise level 5 min [pattern 1: 39.0 vs 41.2 mg.dl-1, pattern 2: 37.1 vs 39.2 mg.dl-1, pattern 3: 38.8 vs 42.7 mg.dl-1] and 24 h [pattern 1: 39.0 vs 39.4 mg.dl-1, pattern 2: 37.1 vs 39.1 mg.dl-1, pattern 3: 38.8 vs 42.6 mg.dl-1] post-exercise. Total HDL-C declined to pre-exercise values 48 h post-exercise in all patterns. HDL2-C was lower (p < 0.05) than pre-exercise 48 h for all exercise patterns. For all patterns, HDL3-C levels were higher (p < 0.05) at the 5 min and 48 h post-exercise time points than at the pre-exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Counting diabetes in the next millennium. Application of capture-recapture technology

Monitoring diabetes is critical for our understanding of the etiology and natural history of disease and for public health actions. However, traditional methods for monitoring are either too expensive (e.g., IDDM registries, NIDDM-OGTT prevalence surveys) or too inaccurate (routinely collected data or passive surveillance) for broad accurate, national programs for monitoring the incidence and prevalence of disease. We suggest that one technology called capture-recapture would considerably increase our ability to "count" diabetes, both nationally and globally. Implementation of this approach could lead to accurate inter- and intracountry data on rates of disease. Moreover, such tracking of diabetes could serve as the model for the monitoring of all disease in the 21st century and beyond.

Insulin-dependent diabetes mellitus, physical activity, and death

The beneficial effect of physical activity in the general population is well known, but, to the authors' knowledge, has not been reported for persons with insulin-dependent diabetes mellitus. In a cohort of 548 diabetes patients followed as part of the Pittsburgh Insulin-dependent Diabetes Mellitus Morbidity and Mortality Study, physical activity was ascertained by survey in 1981, and mortality was ascertained through January 1, 1988. Cases were also compared with non-diabetic sibling controls. Activity level among cases varied inversely with the occurrence of diabetic complications. Overall activity level was inversely related to mortality risk. Sedentary males (< 1,000 kcal/week) were three times more likely to die than active males (> 2,000 kcal/week). A similar, but statistically nonsignificant, relation was seen in females. Cox proportional hazards analysis controlling for potential confounders (age, body mass index, insulin dose, reported diabetes complications, cigarette smoking, and current alcohol drinking) similarly revealed that activity level was inversely associated with mortality risk. Comparison of cases with non-diabetic sibling controls identified similar activity levels for the two groups. The results suggest that activity is not detrimental with regard to mortality, and may in fact provide a beneficial effect in terms of longevity in diabetes patients.

Epidemiology of insulin-using commercial motor vehicle drivers. Major variability of state licensing requirements in the U.S

OBJECTIVE

Licensing agencies in many areas, including the U.S., prohibit insulin-using individuals from driving CMVs or large trucks. This study examined the debate over the risks of licensing insulin-using individuals to drive CMVs as an occupation, and the variations in regulations of different states.

RESEARCH DESIGN AND METHODS

As part of an ongoing review of the regulations governing interstate commerce in the U.S., we surveyed all 50 states and Washington, D.C. to determine the regulations concerning intrastate driving. We received responses from 48 states and D.C., representing 95% of the U.S. population.

RESULTS

Only 9 states reported preventing insulin users from acquiring a CMV license, whereas 39 states and D.C. permitted licensing within state boundaries. Of the states allowing insulin users to drive, 26 placed special requirements on CMV licensing.

CONCLUSIONS

The results indicate that, despite a standardized U.S. federal law for driving across states, enormous variability exists in the policies for driving within states, ranging from no restrictions to a complete ban on CMV driving for insulin users.

Autoimmunity and genetics contribute to the risk of insulin-dependent diabetes mellitus in families: islet cell antibodies and HLA DQ heterodimers

The risk for insulin-dependent diabetes mellitus (IDDM) associated with genetic susceptibility markers at the human leukocyte antigen (HLA) DQA1 and DQB1 loci was evaluated among individuals with and those without islet cell antibodies. A total of 108 antibody-positive parents and siblings of IDDM patients from the Pittsburgh registry were identified among 1,592 who were screened. HLA-DQ molecular typing was performed on 79 of these individuals and on 78 antibody-negative relatives. There were similar proportions of homozygotes for both of the diabetogenic alleles DQA1 arginine-52 (R/R) and DQB1 non-aspartate-57 (nD/nD) among the antibody-positive and antibody-negative relatives (19.0 and 15.4%, respectively). However, subsequent development of IDDM was restricted to individuals who were both antibody positive and carried the potential to make at least one diabetogenic DQ heterodimer. A dose-response effect was observed among the antibody-positive relatives, in which two of 18 capable of generating one diabetogenic heterodimer and six of 29 generating two heterodimers became insulin requiring. Nine of 15 who were homozygous for both R/R and nD/nD, coding exclusively for diabetogenic variants, became diabetic over the course of the follow-up. With a multivariate model, the relative risk for IDDM among those with islet cell antibodies who were also R/R and nD/nD was estimated to be 229.3 compared with those lacking both, after age and sex were controlled for. The data suggest that while autoimmunity, indicated by the presence of cytoplasmic islet cell antibodies may be relatively common, it progresses only in those with variant HLA-DQ molecules.

Insulin-dependent diabetes mellitus in native Estonians and immigrants to Estonia

The authors compared the epidemiology of childhood insulin-dependent diabetes mellitus in Estonia during 1980-1989 between native Estonians and an immigrant group that consisted mainly of Russians. The average annual incidence of diabetes mellitus was significantly higher in Estonians (11.8 per 100,000 children aged less than 15 years; 95% confidence interval (CI) 10.4-13.3) than in non-Estonians (7.6 per 100,000 children aged less than 15; 95% CI 6.2-9.4). This difference appeared in both sexes. The highest incidence in both Estonians and non-Estonians was recorded in 1982, when the incidence in the immigrant population was twice as high as the baseline level. These data indicate that immigrant populations need not acquire the same risk of insulin-dependent diabetes as the native population.

Early infant diet and risk of IDDM in blacks and whites. A matched case-control study

OBJECTIVE

To investigate the role of early infant feeding in the development of insulin-dependent diabetes mellitus (IDDM) and to determine whether an association exists in both blacks and whites.

RESEARCH DESIGN AND METHODS

Black and white diabetic subjects were recruited from the Allegheny County and Children's Hospital of Pittsburgh IDDM Registries. Extensive infant diet histories were obtained from the diabetic subjects and their nondiabetic siblings, who were used as nondiabetic control subjects. Each diabetic subject was matched outside his/her family to an unrelated nondiabetic control subject on birth order, birth year (+/- 2 yr), and race, which resulted in 211 case-control pairs with a mean birth year of 1967.

RESULTS

In whites, diabetic subjects were less likely to have been breast-fed than control subjects (odds ratio [OR] 0.5, 95% confidence interval [CI] 0.3, 0.9). Breast-feeding prevalence did not differ between black diabetic subjects and control subjects. Duration of overall and exclusive breast-feeding did not differ between diabetic and control subjects in the black and white cohorts. The following analyses, which examined whether the timing of the first breast milk substitute to which the infant was exposed differed between diabetic and control subjects, were conducted for exposure to any breast milk substitute and to breast milk substitutes that were cow's milk based. In whites, age at exposure to any breast milk substitutes and cow's milk-based substitutes were similar between diabetic and control subjects. In blacks, the first exposure to breast milk substitutes occurred significantly earlier for any substitute (5.1 vs. 11.9 wk, P = 0.02) and marginally earlier for cow's milk-based substitutes (3.9 vs. 8.5 wk, P = 0.07) in diabetic subjects compared with control subjects. The first exposure to breast milk substitutes was more likely to occur by 3 mo of age in black diabetic subjects compared with black control subjects (OR 3.3, 95% CI 1.1-10.0) after adjusting for maternal age at birth. The addition of breast-feeding status to the model only slightly weakened this association in blacks.

CONCLUSIONS

The analyses of this study cohort suggest that the observed protective effect of breast-feeding on the risk of IDDM may be related to differences in the age at exposure to breast milk substitutes in blacks but not in whites.

Genetic, immunological, and metabolic determinants of risk for type 1 diabetes mellitus in families

Prospective studies of the relatives of people with Type 1 diabetes can provide insights into risk factors for processes leading to the ultimate destruction of the pancreatic islet B-cells. Relatives ascertained through the Children's Hospital of Pittsburgh diabetes registry were followed and rates of conversion to diabetes were determined. We studied the role of genetic and immunological markers, and used the oral glucose tolerance test (OGTT) to study metabolic disturbances among first-degree relatives. A group of siblings was serotyped for the HLA-A and -B antigens, and the degree of HLA haplotype sharing with the diabetic sibling was established. Later, islet cell antibody (ICA) assays were performed, and subjects were followed to determine the predictive value of ICA testing for the subsequent development of diabetes. The rate of conversion to diabetes among the siblings was 14 times greater than the rate observed in the general population from which they come. This is comparable to rates observed by other centres following relatives of people with Type 1 diabetes. Impaired glucose tolerance (by National Diabetes Data Group (USA) criteria) carried a three-fold greater risk for subsequent Type 1 diabetes than did a normal OGTT. Those relatives with detectable ICA were about 50 times more likely to convert to diabetes than were those without ICA. In a group of siblings in whom HLA haplotype sharing was determined, the prevalence of detectable ICA was greater among those who were HLA-identical to the diabetic sibling (9.9%) than among those who were haplo-identical (5.3%) or completely dissimilar (2.4%) at the HLA-A and -B regions.(ABSTRACT TRUNCATED AT 250 WORDS)

Monitoring the incidence of myocardial infarctions: applications of capture-mark-recapture technology

It is critical to monitor the incidence of myocardial infarction. Typically, death certificates have been used as a proxy for incidence, however, these have been found to be crude as they lag behind changes in incidence. In the last decade several myocardial infarction registries have been established, however, these registries are still too limited in geographical spread to assess either national or global trends of heart attack. Here we suggest that employing an alternate approach, that of capture-mark-recapture, would be helpful to provide accurate monitoring both within and between countries. This method would complement existing registries by providing a simple and inexpensive means to provide accurate heart attack data across broad geographical areas and time.

The epidemiology of low back pain in an adolescent population

We assessed the prevalence of low back pain (LBP) in a cohort of 1242 adolescents (aged 11 through 17) currently participating in a 4-year prospective study of medically treated injuries. Overall, 30.4% of the adolescents reported LBP. The impact of LBP in adolescents was considerable, with one third resulting in restricted activity and 7.3% seeking medical attention. Life-table analysis demonstrated that by age 15, the prevalence of LBP increased to 36%. There were few differences by gender or race. These results suggest that LBP in adolescents is a serious public health problem.

Sex differences in secondary attack rate of IDDM to siblings of probands through older ages. Pittsburgh Etiology of IDDM Study

OBJECTIVE

To determine the descriptive epidemiological patterns of the secondary attack rate of insulin-dependent diabetes mellitus (IDDM) among siblings of probands through older ages.

RESEARCH DESIGN AND METHODS

A family history analysis was performed on 1774 IDDM probands who were diagnosed or seen within 1 yr of diagnosis at Children's Hospital of Pittsburgh from 1 January 1950 through 31 December 1981. The probands were discharged on insulin and were diagnosed at less than 17 yr of age. The time frame permitted the risk of IDDM for siblings of probands to be calculated over a broad spectrum of age.

RESULTS

Risk estimates for the 3966 full natural siblings through 10, 20, and 30 yr of age were 1.6, 4.1, and 6.3%, respectively. Secondary attack rates were equivalent for male and female siblings through 15 yr of age (3%); however, the risk to males increased an additional 4% between 16 and 30 yr of age compared with 2.5% for females (P = 0.01). There was no evidence of an excess sex concordance among affected sibling pairs.

CONCLUSIONS

Males have a greater secondary attack rate of IDDM at older ages than females. This may be due to an increased exposure to environmental agents among males or protective influences operating among females.

International comparisons of IDDM mortality. Clues to prevention and the role of diabetes care

A striking difference in all-cause mortality has been noted between individuals with insulin-dependent diabetes mellitus (IDDM) from Finland and Allegheny County, PA. Mortality rates among people 25-37 yr of age from the Allegheny County IDDM Registry were over two times greater than the rates observed from the Finland IDDM Registry. Applying the Finnish rate to the structure of the IDDM population from Allegheny County suggests that about one-half of the deaths in the Allegheny County cohort may be theoretically preventable. Most deaths that might be avoided appear to be caused by the acute complications of diabetes. Deaths from acute-related causes were higher (as a proportion of all deaths) in the Allegheny County cohort than in Finland (46.2 vs. 33.3%). There is some indication that barriers to health care may be present among individuals with IDDM in the United States. Individuals without health insurance from the Children's Hospital IDDM Registry in Pittsburgh had fewer physician visits than those with insurance. Even for those with insurance, out-of-pocket health-care expenses were significant. People with lower household incomes (less than $20,000) spent more, as a percentage of their income, on medical supplies than those with higher incomes and may have been less likely to monitor blood glucose levels and visit an eye doctor because of it. These findings suggest that health system barriers, such as the access to care and the financial burden of diabetes care, in the United States may be affecting the health of adults with IDDM. Further investigation is needed to clarify the extent of barriers to care in IDDM and their contribution to adverse health outcomes.

The incidence of male childhood type 1 (insulin-dependent) diabetes mellitus is rising rapidly in The Netherlands

This study evaluates the cumulative incidence of Type 1 (insulin-dependent) diabetes mellitus in male army conscripts 0-18 (inclusive) years of age in the Netherlands (birth cohorts) over 10 years. Data from 2136 cases were retrieved from files of the conscript registry of the Royal Dutch Army. Ascertainment was sought by the capture-recapture method, achieving an average ascertainment rate of 89.7%. Poisson regression modelling was used to determine the change in incidence over time. A significant non-linear increase in the incidence of insulin-dependency in the birth cohorts of 1960-1970 was found. The cumulative incidences of the early birth cohorts 1.85/1000 (1960), 1.76/1000 (1961), 1.11/1000 (1962) were considerably lower than of the later birth cohorts 1.96/1000 (1968), 2.11/1000 (1969), 2.12/1000 (1970). Overall the risk of Type 1 diabetes increased on the average 4.4% with each annual birth cohort. Only for the 1962 birth cohort was a significant dip in the incidence observed. The results indicate a rapidly increasing incidence of diabetes in males in the Netherlands consistent with the concurrent rapid rise in Northern Europe, found in both sexes.

The importance of incidence registries for connective tissue diseases

There have been numerous studies conducted to determine the frequencies of CTD. These investigations, however, were usually not population based, relied on data sources set up primarily for administrative purposes, lacked unified methodologies for case definitions and verification, and failed to estimate the level of case ascertainment. Population based registries offer an alternative to past approaches and should not be overlooked for CTD. We propose that a standardized approach, as outlined above, will facilitate the development of registries and will permit the evaluation of the incidence of CTD across race, geographic area, and time. The establishment of standardized population based registries would form the foundation of a coordinated national and global effort to identify the etiology, and perhaps preventative measures, for these serious conditions.

Familial and sporadic insulin-dependent diabetes: evidence for heterogeneous etiologies?

Heterogeneity within insulin-dependent diabetes mellitus (IDDM) has been hypothesized, but few studies have focused on differences which may exist between familial and sporadic IDDM cases. Presenting characteristics for 330 white, newly diagnosed IDDM cases were evaluated. Familial cases were older (10.2 +/- 5.1 years vs 7.9 +/- 4.2 years, P = 0.010) and had, on average, less severe metabolic disturbances at presentation, as demonstrated by lower mean hemoglobin A1 (12.6 +/- 2.4% vs 14.4 +/- 2.6%, P = 0.001) and mean insulin dose at discharge (0.62 +/- 0.35 U/kg/day vs 0.85 +/- 0.29 U/kg/day, P less than 0.001), and higher mean plasma bicarbonate concentrations (19.3 +/- 3.9 mmol/l vs 15.8 +/- 5.9 mmol/l, P = 0.023) and mean plasma C-peptide levels (0.35 +/- 0.36 pmol/ml vs 0.14 +/- 0.15 pmol/ml, P less than 0.001). Further analyses on a subset of IDDM cases (n = 100) indicated that initial differences in metabolic indices observed at diagnosis were no longer apparent at one-year post-diagnosis. These results suggest that the etiology of familial and sporadic IDDM is similar and that the less severe presentation observed at diagnosis in the familial cases may be due to earlier identification of the disease, reflecting increased parental knowledge of diabetic symptoms and/or frequent testing for diabetes.

Comparison of incidence of IDDM in childhood between Estonia and Finland, 1980-1988

OBJECTIVE

To compare nationwide incidence of childhood insulin-dependent diabetes mellitus (IDDM) in children aged 0-14 yr between Estonia and Finland during 1980-1988. For Estonia, which has a population genetically and linguistically related to Finland, only limited information was available. Finland has the highest incidence of IDDM in the world.

RESEARCH DESIGN AND METHODS

The registration of all new cases of IDDM in Estonia was conducted by the local district pediatricians who reported every newly diagnosed diabetic patient to the Republic Endocrinology Centre. Registration of all new cases of IDDM in Finland was based on the statistics of the Social Insurance Institution, which approves free-of-charge insulin treatment for diabetes. These data were validated with one or more additional data sources. The case ascertainment rate approached 100% in both countries.

RESULTS

The average yearly incidence of IDDM standardized for age for the years 1980-1988 in Estonia was approximately 33% of that in Finland. Among males it was 11.3 (95% confidence interval [CI] 10.3-12.3) per 100,000 in Estonia and 35.1 (95% CI 33.4-36.9) per 100,000 in Finland, and among females 10.1 (95% CI 9.2-11.1) per 100,000 in Estonia and 30.4 (95% CI 28.8-32.1) per 100,000 in Finland. When the two periods 1980-1982 and 1986-1988 were compared, the age-standardized incidence in Estonia remained unchanged, whereas in Finland it increased approximately 20%.

CONCLUSIONS

The data between two populations who are ethnically and linguistically similar and live geographically close but in a different environment, provides further evidence that both genetic and environmental factors are contributing to the risk of IDDM.

The interface between epidemiology and molecular biology in the search for the causes of insulin-dependent diabetes mellitus

Epidemiological techniques have been utilized to accumulate new knowledge about insulin-dependent diabetes mellitus (IDDM), leading to important insights into the disease process and the alteration of these mechanisms when viewed from a geographic or population base. More recently, highly powerful and sophisticated techniques of molecular biology have been added to the research arsenal, extending the knowledge on the genetic basis for IDDM and the probable environmental factors involved. The development and growth of the new discipline of epidemiological genetics promises exciting new developments for the future of our field as well as that of other major medical problems having a genetic base, but significantly influenced by environmental factors. This review stresses the importance of carefully validated diabetes registries in the study of the epidemiology of IDDM. The Children's Hospital of Pittsburgh and the University of Pittsburgh Medical Center have spear-headed the development of such registries, worldwide. The first international meeting on IDDM epidemiology in 1983 gave as a result, i.e., the finding that there were truly remarkable differences in the risk of developing IDDM depending upon the geographic location of the individual. Later collaborative work via the Diabetes Epidemiology Research International (DERI) group has confirmed the previous finding and added the description of secular trends and epidemics of IDDM. It is remarkable that the incidence rate of IDDM in children below 15 years vary from 1/100,000/yr in the Orient to 35/100,000/yr in Finland. The epidemiological approach in the study of IDDM has also stimulated research into the various facets of the etiology of the disease, genetic factors, autoimmune mechanisms and environmental factors.(ABSTRACT TRUNCATED AT 250 WORDS)

Genetics of diabetes. Genes and environment

Many other autoimmune and chronic diseases exhibit marked geographic variation in incidence, which has been attributed to environmental differences across populations (Hutt and Burkitt, 1986). The results of our international IDDM research have provided evidence for the importance of large genetic variations in the frequency of HLA susceptibility genes between racial groups and countries. One may speculate that differences in the prevalence of susceptibility genes for other chronic diseases exist and significantly contribute to the geographic patterns of incidence of these disorders. Other autoimmune diseases are known to have epidemiological features similar to those described for IDDM. Although they are also characterized by an underlying HLA-related susceptibility, environmental factors are known to play an important aetiological role (Tiwari and Terasaki, 1985). DNA polymorphisms of the DR, DQ and DP locus antigens are associated with various autoimmune diseases (Todd et al, 1988; Thorsby et al, 1989). These molecular variations are similar to those described for IDDM, in that they are typically related to the hypervariable regions of the molecule and, thus, affect the peptide binding ability of the antigen. Based on the evidence for IDDM, population differences in the frequency of other HLA susceptibility genes are likely to be major determinants of the geographic distribution of diseases such as rheumatoid arthritis and multiple sclerosis. The epidemiological approach outlined in this review is, thus, applicable to other autoimmune diseases and will significantly contribute to our knowledge of the aetiology of these disorders. The emerging field of molecular epidemiology represents a new research approach which will lead to a better understanding of the relationships between specific risk factors and the aetiology of chronic diseases within populations and across the world.

Health, life, and automobile insurance characteristics in adults with IDDM

OBJECTIVE

To determine whether people with insulin-dependent diabetes mellitus (IDDM) were compromised in their access to insurance.

RESEARCH DESIGN AND METHODS

A case-control study of 158 people with IDDM and 158 nondiabetic siblings matched for age and sex was conducted to evaluate the health, life, and automobile insurance characteristics and history of people with IDDM.

RESULTS

Health insurance coverage (yes/no) among the IDDM and sibling control subjects was similar. More than 90% of the IDDM and control respondents had insurance through a private third-party source, and this insurance did not differ by type of plan, coverage, or premium. However, Medicare coverage was more common among the IDDM subjects and was associated with the presence of severe diabetic complications. IDDM subjects were also more likely to have been denied a health insurance policy by an insurer than were the control subjects (23 vs. 1%, P less than 0.001). Similarly, there was no difference between the IDDM and sibling control subjects in the number who had a life or automobile insurance policy. However, life and automobile insurance refusal was much more frequent among the IDDM respondents, more so for life (55 vs. 0%, P less than 0.001) than for automobile (12 vs. 4%, P less than 0.05) insurance.

CONCLUSIONS

These results suggest that access to insurance is severely compromised for people with IDDM. Although most of those with IDDM are able to find some form of insurance, it is evident that on average they must go to extra lengths to find it. These data and a changing insurance environment emphasize the need to reexamine, as a society, the importance of insurance for people with chronic disease, particularly IDDM.

The association of physical activity and diabetic complications in individuals with insulin-dependent diabetes mellitus: the Epidemiology of Diabetes Complications Study--VII

The relationship between leisure-time physical activity and diabetes complications was examined in 628 individuals with insulin-dependent diabetes mellitus. Neuropathy was based upon clinical exam; retinopathy by fundus photographs; nephropathy by urine samples and macrovascular disease by clinician diagnosis. Past week physical activity was found to be inversely related to complication status but since current inactivity could be the result of the complications, historical activity (estimated leisure activity during ages 14-17) was also examined in relation to complication status. Males reporting higher levels of historical physical activity had a significantly lower prevalence of nephropathy and neuropathy but not retinopathy as demonstrated by multivariate analysis (controlling for duration of disease, age, and current activity levels). The lack of similar findings in women may be due to their low levels of reported physical activity. The consistent relationship between historical leisure physical activity and development of complications in males suggests that activity may be protective or at least not detrimental to the individual with insulin-dependent diabetes.