Older age of childhood type 1 diabetes onset is associated with islet autoantibody positivity >30 years later: the Pittsburgh Epidemiology of Diabetes Complications Study

AIMS

To examine the association between islet autoantibody positivity and clinical characteristics, residual β-cell function (C-peptide) and prevalence of complications in a childhood-onset (age <17 years), long-duration (≥32 years) type 1 diabetes cohort.

METHODS

Islet autoantibodies (glutamic acid decarboxylase, insulinoma-associated protein 2 and zinc transporter-8 antibodies) were measured in the serum of participants who attended the 2011-2013 Pittsburgh Epidemiology of Diabetes Complications study follow-up examination (n=177, mean age 51 years, diabetes duration 43 years).

RESULTS

Prevalences of islet autoantibodies were: glutamic acid decarboxylase, 32%; insulinoma-associated protein 2, 22%; and zinc transporter-8, 4%. Positivity for each islet autoantibody was associated with older age at diabetes onset (glutamic acid decarboxylase antibodies, P=0.03; insulinoma-associated protein 2 antibodies, P=0.001; zinc transporter-8 antibodies, P<0.0001). Older age at onset was also associated with an increasing number of autoantibodies (P = 0.001). Glutamic acid decarboxylase antibody positivity was also associated with lower HbA_1c (P = 0.02), insulinoma-associated protein 2 antibody positivity was associated with lower prevalence of severe hypoglycaemic episodes (P=0.02) and both distal and autonomic neuropathy (P=0.04 for both), and zinc transporter-8 antibody positivity was associated with higher total and LDL cholesterol (P=0.01). No association between autoantibody positivity and C-peptide was observed.

CONCLUSIONS

The strong association between islet autoantibody positivity and older age at type 1 diabetes onset supports the hypothesis of a less aggressive, and thus more persistent, immune process in those with older age at onset. This observation suggests that there may be long-term persistence of heterogeneity in the underlying autoimmune process.

The emergence of vampire bat rabies in Uruguay within a historical context

Pathogen spillover from wildlife to humans or domestic animals requires a series of conditions to align with space and time. Comparing these conditions between times and locations where spillover does and does not occur presents opportunities to understand the factors that shape spillover risk. Bovine rabies transmitted by vampire bats was first confirmed in 1911 and has since been detected across the distribution of vampire bats. However, Uruguay is an exception. Uruguay was free of bovine rabies until 2007, despite high-cattle densities, the presence of vampire bats and a strong surveillance system. To explore why Uruguay was free of bovine rabies until recently, we review the historic literature and reconstruct the conditions that would allow rabies invasion into Uruguay. We used available historical records on the abundance of livestock and wildlife, the vampire bat distribution and occurrence of rabies outbreaks, as well as environmental modifications, to propose four alternative hypotheses to explain rabies virus emergence and spillover: bat movement, viral invasion, surveillance failure and environmental changes. While future statistical modelling efforts will be required to disentangle these hypotheses, we here show how a detailed historical analysis can be used to generate testable predictions for the conditions leading to pathogen spillover.

The effects of state-level expenditures for home- and community-based services on the risk of becoming a long-stay nursing home resident after hip fracture

SUMMARY

This study measures the effect of spending policies for long-term care services on the risk of becoming a long-stay nursing home resident after a hip fracture. Relative spending on community-based services may reduce the risk of long-term nursing home residence. Policies favoring alternative sources of care may provide opportunities for older adults to remain community-bound.

INTRODUCTION

This study aims to understand how long-term care policies affect outcomes by investigating the effect of state-level spending for home- and community-based services (HCBSs) on the likelihood of an individual's nursing home placement following hip fracture.

METHODS

This study uses data from the 5% sample of Medicare beneficiaries from 2005 to 2010 to identify incident hip fractures among dual-eligibility, community-dwelling adults aged at least 65 years. A multilevel generalized estimating equation (GEE) model estimated the association between an individual's risk of nursing home residence within 1 year and the percent of states' Medicaid long-term support service (LTSS) budget allocated to HCBS. Other covariates included expenditures for Title III services and individual demographic and health status characteristics.

RESULTS

States vary considerably in HCBS spending, ranging from 17.7 to 83.8% of the Medicaid LTSS budget in 2009. Hip fractures were observed from claims among 7778 beneficiaries; 34% were admitted to a nursing home and 25% died within 1 year. HCBS spending was associated with a decreased risk of nursing home residence by 0.17 percentage points (p 0.056).

CONCLUSIONS

Consistent with other studies, our findings suggest that state policies favoring an emphasis on HCBS may reduce nursing home residence among low-income older adults with hip fracture who are at high risk for institutionalization.

Prevalence and incidence of clinically recognized cases of Type 1 diabetes in children and adolescents in Rwanda, Africa

AIMS

To determine prevalence and incidence estimates for clinically recognized cases of Type 1 diabetes from the Life For a Child Program (LFAC) with onset < 26 years in six representative districts, and the capital, of Rwanda.

METHODS

Cases were identified from the LFAC registry and visits to district hospitals. Denominators were calculated from district-level population surveys. Period prevalence data were collected from 1 August 2011 to 31 July 2012 and annual incidence rates were calculated, retrospectively, for 2004-2011. Ninety-five per cent confidence intervals (95% CI) were calculated using a Poisson distribution.

RESULTS

The prevalence of known Type 1 diabetes in seven districts in Rwanda for ages < 26 years was 16.4 [95% CI 14.6-18.4]/100 000 and for < 15 years was 4.8 [3.5-6.4]/100 000. Prevalence was higher in females (18.5 [15.8-21.4]/100 000) than males (14.1 [11.8-16.7]/100 000; P = 0.01) and rates increased with age. The annual incidence rate for those < 26 years was stable between 2007 and 2011 with a mean incidence over that time of 2.7 [2.0-3.7]/100 000 ( < 15 years = 1.2 [0.5-2.0]/100 000). Incidence rates were higher in females than males and peaked in males at ages 17 and 22 years and in females at age 18 years.

CONCLUSIONS

Our report of known Type 1 diabetes cases shows lower incidence and prevalence rates in Rwanda than previously reported in the USA and most African countries. Incidence of recognized cases has increased over time, but has recently stabilized. However, the likelihood of missed cases due to death before diagnosis and misdiagnosis is high and therefore more definitive studies are needed.

Characterizing the transition from paediatric to adult care among emerging adults with Type 1 diabetes

AIMS

The goals of the study were to describe the transition of youth with Type 1 diabetes from paediatric to adult healthcare services, examine the link of this transition with self care and glycaemic control, and distinguish youth who received medical treatment from different physicians in terms of demographic and parent relationship variables.

METHODS

Youth with Type 1 diabetes (n = 118) were enrolled in a prospective study that examined the transition from the paediatric to adult healthcare systems and were evaluated during their senior year of high school (time 1) and 1 year later (time 2). Data on self care, glycaemic control and parent relationship were collected.

RESULTS

The majority of youth saw a paediatric endocrinologist at both assessments (n = 64); others saw an adult care physician at both assessments (n = 26) or transitioned from a paediatric endocrinologist to an adult care physician (n = 19). Nine youth saw no physician between time 1 and time 2. There were group differences in demographic and parent relationship variables and self-care behaviour and glycaemic control related to the transition of care. Youth who remained in the paediatric healthcare system had the best self care and did not experience declines in glycaemic control over time.

CONCLUSIONS

Early transition from the paediatric healthcare system to the adult healthcare system is associated with psychosocial variables and worse glycaemic control. Future research should identify factors that determine optimal timing and strategies to avoid deterioration of care and control during this transition.

Clinical and demographic factors associated with fractures among older Americans

Medicare claims data were used to investigate associations between history of previous fractures, chronic conditions, and demographic characteristics and occurrence of fractures at six anatomic sites. The study confirmed previously established associations for hip and spine fractures and identified several new associations of interest for nonhip, nonspine fractures.

INTRODUCTION

This study investigates the associations of a history of fracture, comorbid chronic conditions, and demographic characteristics with incident fractures among Medicare beneficiaries. The majority of fracture incidence studies have focused on the hip and on white females. This study examines a greater variety of fracture sites and more population subgroups than prior studies.

METHODS

We used Medicare claims data to examine the incidence of fracture at six anatomic sites in a random 5% sample of Medicare beneficiaries during the time period 2000 through 2005.

RESULTS

For each type of incident fracture, women had a higher rate than men, and there was a positive association with age and an inverse association with income. Whites had a higher rate than nonwhites. Rates were lowest among African-Americans for all sites except ankle and tibia/fibula, which were lowest among Asian-Americans. Rates of hip and spine fracture were highest in the South, and fractures of other sites were highest in the Northeast. Fall-related conditions and depressive illnesses were associated with each type of incident fracture, conditions treated with glucocorticoids with hip and spine fractures and diabetes with ankle and humerus fractures. Histories of hip and spine fractures were associated positively with each site of incident fracture except ankle; histories of nonhip, nonspine fractures were associated with most types of incident fracture.

CONCLUSIONS

This study confirmed previously established associations for hip and spine fractures and identified several new associations of interest for nonhip, nonspine fractures.

Characterizing sudden death and dead-in-bed syndrome in Type 1 diabetes: analysis from two childhood-onset Type 1 diabetes registries

AIMS

Type 1 diabetes mellitus increases the risk for sudden unexplained death, generating concern that diabetes processes and/or treatments underlie these deaths. Young (< 50 years) and otherwise healthy patients who are found dead in bed have been classified as experiencing 'dead-in-bed' syndrome.

METHODS

We thus identified all unwitnessed deaths in two related registries (the Children's Hospital of Pittsburgh and Allegheny County) yielding 1319 persons with childhood-onset (age < 18 years) Type 1 diabetes diagnosed between 1965 and 1979. Cause of death was determined by a Mortality Classification Committee (MCC) of at least two physician epidemiologists, based on the death certificate and additional records surrounding the death.

RESULTS

Of the 329 participants who had died, the Mortality Classification Committee has so far reviewed and assigned a final cause of death to 255 (78%). Nineteen (8%) of these were sudden unexplained deaths (13 male) and seven met dead-in-bed criteria. The Mortality Classification Committee adjudicated cause of death in the seven dead-in-bed persons as: diabetic coma (n =4), unknown (n=2) and cardiomyopathy (n=1, found on autopsy). The three dead-in-bed individuals who participated in a clinical study had higher HbA(1c) , lower BMI and higher daily insulin dose compared with both those dying from other causes and those surviving.

CONCLUSIONS

Sudden unexplained death in Type 1 diabetes seems to be increased 10-fold and associated with male sex, while dead-in-bed individuals have a high HbA(1c) and insulin dose and low BMI. Although sample size is too small for definitive conclusions, these results suggest specific sex and metabolic factors predispose to sudden unexplained death and dead-in-bed death.

"Pathologic" fractures: should these be included in epidemiologic studies of osteoporotic fractures?

Pathologic fractures are often excluded in epidemiologic studies of osteoporosis. Using Medicare administrative data, we identified persons with vertebral and hip fractures. Among these, 48% (vertebral) and 3% (hip) of the fractures were coded as pathologic. Only 25% and 66% of persons with these pathologic fractures had evidence for malignancy.

INTRODUCTION

Analyses of osteoporosis-related fractures that use administrative data often exclude pathologic fractures (ICD-9 733.1x) due to concern that these are caused by cancer. We examined "pathologic" fractures of the vertebrae and hip to evaluate their contribution to fracture incidence and assessed the evidence for a malignancy.

METHODS

We studied US Medicare beneficiaries age > or =65 with new fractures identified using ICD-9 diagnosis codes 733.13 (pathologic vert), 805.0, 805.2, 805.4, 805.8 (nonpathologic vert); and 733.14 (pathologic hip), 820.0, 820.2, 820.8 (nonpathologic hip). We further examined the proportion of cases with a diagnosis of a malignancy proximate to the fracture.

RESULTS

We identified 44,120 individuals with a vertebral fracture and 60,354 with a hip fracture. Approximately 48% of vertebral fractures and 3% of hip fractures were coded as pathologic. For only approximately 25% of persons with a "pathologic" vertebral fracture ICD-9 code, but 66% of persons with a "pathologic" hip fracture, there was evidence of a possible cancer diagnosis.

CONCLUSION

Among US Medicare beneficiaries, one fourth of pathologic vertebral fracture and two thirds of pathologic hip fracture cases had evidence for a malignancy. Particularly for vertebral fractures, excluding persons with pathologic fractures in epidemiologic analyses that utilize administrative claims data substantially underestimates the burden of fractures due to osteoporosis.

The geographic availability and associated utilization of dual-energy X-ray absorptiometry (DXA) testing among older persons in the United States

Using national Medicare data from 1999-2006, we evaluated the relationship between travel distance and receipt of dual-energy X-ray absorptiometry (DXA). After adjusting for potentially confounding factors, travel distance was strongly associated with DXA testing. Rural residents were most strongly dependent on the availability of DXAs performed in physician offices.

INTRODUCTION

Medicare reimbursement for DXAs performed in non-facility settings (e.g., physician offices) decreased in 2007. With declining reimbursement, some DXA providers may cease providing this service, which would increase travel distance for some people. The impact of travel distance on access to DXA is unclear.

METHODS

Using national Medicare data, we identified claims for DXA to evaluate trends in the number and locations of DXAs performed. Travel distance was the distance from beneficiaries' residence and the nearest DXA provider. Binomial regression evaluated the relationship between travel distance and receipt of DXA.

RESULTS

In 2006, 2.9 million DXAs were performed, a 103% increase since 1999. In 2005-2006, 8.0% of persons were tested at non-facility sites versus 4.2% at facility sites. The remainder (88%) had no DXA. Persons traveling 5-9, 10-24, 25-39, and 40-54, and > or = 55 miles were less likely to receive DXA (adjusted risk ratios = 0.92, 0.79, 0.43, 0.32, and 0.26, respectively, < 5 miles referent). Rural residents were more dependent than urban residents on the availability of DXA from non-facility providers.

CONCLUSION

Approximately two-thirds of DXAs in 2005-2006 were performed in non-facility settings (e.g., physician offices). Rural residents would have preferentially reduced access to DXA if there were fewer non-facility sites.

Changes in glycaemic control and risk of coronary artery disease in type 1 diabetes mellitus: findings from the Pittsburgh Epidemiology of Diabetes Complications Study (EDC)

AIMS/HYPOTHESIS

To complete a comparative analysis of studies that have examined the relationship between glycaemia and cardiovascular disease (CVD)/coronary artery disease (CAD) and perform a prospective analysis of the effect of change in glycosylated Hb level on CAD risk in the Pittsburgh Epidemiology of Diabetes Complications Study (EDC) of childhood-onset type 1 diabetes mellitus (n = 469) over 16 years of two yearly follow-up.

METHODS

Measured values for HbA(1) and HbA(1c) from the EDC were converted to the DCCT-standard HbA(1c) for change analyses and the change in HbA(1c) was calculated (final HbA(1c) minus baseline HbA(1c)). CAD was defined as EDC-diagnosed angina, myocardial infarction, ischaemia, revascularisation or fatal CAD after medical record review.

RESULTS

The comparative analysis suggested that glycaemia may have a stronger effect on CAD in patients without, than in those with, albuminuria. In EDC, the change in HbA(1c) differed significantly between CAD cases (+0.62 +/- 1.8%) and non-cases (-0.09 +/- 1.9%) and was an independent predictor of CAD.

CONCLUSIONS/INTERPRETATION

Discrepant study results regarding the relationship of glycaemia with CVD/CAD may, in part, be related to the prevalence of renal disease. Measures of HbA(1c) change over time show a stronger association with CAD than baseline values.

Progression to insulin-requiring diabetes in seronegative prediabetic subjects: the role of two HLA-DQ high-risk haplotypes

AIMS/HYPOTHESIS

Most Caucasians with Type I (insulin-dependent) diabetes mellitus develop an autoimmune form of diabetes known as Type IA diabetes, based on the presence of humoral responses to islet autoantigens. Alleles at the HLA locus account for the strongest susceptibility to this form of diabetes, which requires insulin therapy. Because a number of patients who develop insulin-requiring diabetes are islet autoantibody negative, the HLA class II haplotypes, DQA1*0501-DQB1*0201 and DQA1*0301-DQB1*0302, were evaluated to assess whether they are an independent risk factor for progression to insulin requirement in first-degree relatives of Type I diabetic patients.

METHODS

Both HLA-DQ genotyping and islet cell autoantibody assessment (insulin, GAD65, IA-2 autoantibodies and cytoplasmic islet cell antibodies) were evaluated prospectively in 74 relatives of Type I diabetic patients who developed diabetes treated with insulin (prediabetics) and in 426 control subjects who did not develop insulin-requiring diabetes. Based on the presence of DQA1*0501-DQB1*0201 and/or DQA1*0301-DQB1*0302, the number of HLA-DQ high-risk haplotypes was assigned as 0, 1 or 2.

RESULTS

A higher prevalence of 2 HLA-DQ high-risk haplotypes was present in seronegative prediabetic subjects as compared to non-diabetic autoantibody negative first-degree relatives (33.3 % vs 10.1 % respectively; p < 0.05). Moreover, in seronegative relatives who developed insulin-requiring diabetes, the presence of 2 HLA-DQ high-risk haplotypes conferred an increased cumulative risk of developing insulin requirement of 27 % at 12.5 years of follow-up, compared to a risk of 6 % for non-diabetic relatives who were antibody-negative and had 0 or 1 HLA-DQ high-risk haplotypes (Log rank p = 0.01).

CONCLUSION/INTERPRETATION

These data provide evidence for a phenotype, which is associated with the absence of conventional islet autoantibodies at initial screening, while usually remaining seronegative, and the presence of 2 HLA-DQ high-risk haplotypes with progression to clinical Type I diabetes after a prolonged follow-up. Given the fact that in humans the highest risk-conferring locus associated and linked to the disease is the HLA cluster, and that HLA-DQ molecules play a key role in the development of autoimmune diabetes, our observations imply that as yet unidentified immunologic abnormalities could well exist in seronegative relatives at risk of developing clinical diabetes and carrying 2 HLA-DQ high-risk haplotypes.

Lipid and blood pressure treatment goals for type 1 diabetes: 10-year incidence data from the Pittsburgh Epidemiology of Diabetes Complications Study

OBJECTIVE

Subjects with type 1 diabetes are at high risk for many long-term complications, including early mortality and coronary artery disease (CAD). Few data are available on which to base goal levels for two major risk factors, namely blood pressure and lipid/lipoproteins. The objective of this study was to determine at which levels of LDL and HDL cholesterol, triglycerides, and blood pressure the relative risks of type 1 diabetic complications increase significantly.

RESEARCH DESIGN AND METHODS

Observational prospective study of 589 patients with childhood-onset type 1 diabetes (<17 years) aged > or =18 years at baseline; 10-year incidence of mortality, CAD, lower-extremity arterial disease, proliferative retinopathy, distal symmetric polyneuropathy, and overt nephropathy. Relative risks were determined using traditional groupings of blood pressure and lipid/lipoproteins, measured at baseline, using the lowest groupings (<100 mg/dl [2.6 mmol/l] LDL cholesterol, <45 mg/dl [1.1 mmol/l] HDL cholesterol, <100 mg/dl [1.1 mmol/l] triglycerides, <110 mmHg systolic blood pressure, and <80 mmHg diastolic blood pressure) as reference. Adjustments for age, sex, and glycemic control were examined.

RESULTS

Driven mainly by strong relationships (RR range 1.8-12.1) with mortality, CAD, and overt nephropathy, suggested goal levels are as follows: LDL cholesterol <100 mg/dl (2.6 mmol/l), HDL cholesterol >45 mg/dl (1.1 mmol/l), triglycerides <150 mg/dl (1.7 mmol/l), systolic blood pressure <120 mmHg, and diastolic blood pressure <80 mmHG: Age, sex, and glycemic control had little influence on these goals.

CONCLUSIONS

Although observational in nature, these data strongly support the case for vigorous control of lipid levels and blood pressure in patients with type 1 diabetes.

T cells of multiple sclerosis patients target a common environmental peptide that causes encephalitis in mice

Multiple sclerosis (MS) is a chronic autoimmune disease triggered by unknown environmental factors in genetically susceptible hosts. MS risk was linked to high rates of cow milk protein (CMP) consumption, reminiscent of a similar association in autoimmune diabetes. A recent rodent study showed that immune responses to the CMP, butyrophilin, can lead to encephalitis through antigenic mimicry with myelin oligodendrocyte glycoprotein. In this study, we show abnormal T cell immunity to several other CMPs in MS patients comparable to that in diabetics. Limited epitope mapping with the milk protein BSA identified one specific epitope, BSA(193), which was targeted by most MS but not diabetes patients. BSA(193) was encephalitogenic in SJL/J mice subjected to a standard protocol for the induction of experimental autoimmune encephalitis. These data extend the possible, immunological basis for the association of MS risk, CMP, and CNS autoimmunity. To pinpoint the same peptide, BSA(193), in encephalitis-prone humans and rodents may imply a common endogenous ligand, targeted through antigenic mimicry.

Type I diabetes and multiple sclerosis patients target islet plus central nervous system autoantigens; nonimmunized nonobese diabetic mice can develop autoimmune encephalitis

Type I diabetes and multiple sclerosis (MS) are distinct autoimmune diseases where T cells target either islet or CNS self-proteins. Unexpectedly, we found that autoreactive T cells in diabetic patients, relatives with high diabetes risk, nonobese diabetic (NOD) mice, and MS patients routinely target classical islet as well as CNS autoantigens. The pathogenic potential of CNS autoreactivity was testable in NOD mice. Pertussis holotoxin, without additional Ags or adjuvants, allowed development of an NOD mouse-specific, autoimmune encephalitis with variable primary-progressive, monophasic, and relapsing-remitting courses. T cells from diabetic donors transferred CNS disease to pertussis toxin-pretreated NOD.scid mice, with accumulation of CD3/IFN-gamma transcripts in the brain. Diabetes and MS appear more closely related than previously perceived. NOD mouse-specific, autoimmune encephalitis provides a new MS model to identify factors that determine alternative disease outcomes in hosts with similar autoreactive T cell repertoires.

Peptide dose, MHC affinity, and target self-antigen expression are critical for effective immunotherapy of nonobese diabetic mouse prediabetes

Cross-reactive T cells that recognize both Tep69 (dominant nonobese diabetic (NOD) T cell epitope in ICA69 (islet cell autoantigen of 69 kDa)) and ABBOS (dominant NOD T cell epitope in BSA) are routinely generated during human and NOD mouse prediabetes. Here we analyzed how systemic administration of these mimicry peptides affects progressive autoimmunity in adoptively transferred and cyclophosphamide-accelerated NOD mouse diabetes. These models were chosen to approximate mid to late stage prediabetes, the typical status of probands in human intervention trials. Unexpectedly, high dose (100 microg) i.v. ABBOS prevented, while Tep69 exacerbated, disease in both study models. Peptide effects required cognate recognition of endogenous self-Ag, because both treatments were ineffective in ICA69null NOD congenic mice adoptively transferred with wild-type, diabetic splenocytes. The affinity of ABBOS for NOD I-A(g7) was orders of magnitude higher than that of Tep69. This explained 1) the expansion of the mimicry T cell pool following i.v. Tep69, 2) the long-term unresponsiveness of these cells after i.v. ABBOS, and 3) precipitation of the disease after low dose i.v. ABBOS. Disease precipitation and prevention in mid to late stage prediabetes are thus governed by affinity profiles and doses of therapeutic peptides. ABBOS or ABBOS analogues with even higher MHC affinity may be candidates for experimental intervention strategies in human prediabetes, but the dose translation from NOD mice to humans requires caution.

Coronary calcium in adults with type 1 diabetes: a stronger correlate of clinical coronary artery disease in men than in women

We studied the relationship of coronary artery calcification (CAC), a marker of coronary atherosclerosis, with prevalent clinical coronary artery disease (CAD) and established cardiovascular disease (CVD) risk factors in a type 1 diabetic population. At the 10-year follow-up examination of the Pittsburgh Epidemiology of Diabetes Complications (EDC) Study cohort, 302 adults (mean age 38.1 +/- 7.8 years) received electron beam tomography (EBT) scanning of the heart and a clinical examination. Clinical CAD was defined as a confirmed history of myocardial infarction (MI), angiographic stenosis > or =50%, Pittsburgh EDC Study physician-diagnosed angina, or ischemic electrocardiogram (ECG). CAC correlated with most CVD risk factors. CAC had 84 and 71% sensitivity for clinical CAD in men and women, respectively, and 100% sensitivity for MI or obstructive CAD. A CACS cut point of 400 was the most efficient coronary calcium correlate of CAD. In subjects with angina only, CAC sensitivity was 83% in men and 46% in women. In logistic regression, CAC, ECG R-R variation, peripheral vascular disease, and Beck Depression Inventory independently correlated with prevalent CAD in men and overall. Except for CAC, the same variables independently correlated with CAD in women, and age also entered the model. CAC was an independent correlate of MI or obstructive CAD in both sexes and was the strongest independent correlate in men, but CAC was not independently associated with angina and ischemic ECG in either sex. It is concluded that EBT-detected CAC is strongly correlated with CAD in type 1 diabetes-particularly in men.

A nonlinear analytical model of the autonomic basis of heart rate variability (HRV)

The sinoatrial (SA) node is responsible for the initiation of cardiac contractions, and integrates charge across its cell membranes on a beat-to-beat basis mainly through the regulation of slow calcium-sodium channels. The time constant (slope) of this integrator and the firing threshold (voltage) of the SA nodal cells are influenced by inputs from both sympathetic and parasympathetic autonomic neural pathways converging on the heart. A model has been developed in Matlab that accounts for cumulative autonomic effects on the SA node's integrator and non-cumulative effects on it's firing threshold, and includes an assessment of the contribution of noise to both sub-systems. Using the model, an assessment of the effect of an arbitrary number of autonomic inputs is made on the beat-to-beat variability of heart rate. Additionally, the contribution of noise and nonlinear fast channel effects are considered. Assignment of particular autonomic control frequencies results in physiologically realistic heart rate versus time outputs. Physiological heart rate variability modes such as autonomic control spectra in heart rate, mode-locking, and other complex behaviors can be demonstrated. The results of this model may then be compared with physiological data in which autonomic inputs are controlled by paced breathing or other physiological stimulus.

Hypoglycemia: a complication of diabetes therapy in children

Hypoglycemia is the most common acute complication in insulin-treated type 1 diabetic patients. Most surveys have demonstrated that the tighter the glycemic control, and the younger the patient, the greater the frequency of both mild and severe hypoglycemia. However, people in poor metabolic control, with high glycosylated hemoglobin levels, are not protected from experiencing severe hypoglycemia. Focusing on the pediatric population, we review new or controversial issues surrounding the prevalence of hypoglycemia, its causes, its consequences and preventive strategies, and discuss possible mechanisms underlying the variability of responses to hypoglycemia.

Are predictors of coronary heart disease and lower-extremity arterial disease in type 1 diabetes the same? A prospective study

In the Type 1 diabetes population, coronary heart disease (CHD) and lower-extremity arterial disease (LEAD) are the two common macrovascular complications leading to early mortality and morbidity. However, it is not clear if these two complications share the same risk factors. The Pittsburgh Epidemiology of Diabetes Complications (EDC) Study prospectively examined and compared the risk factors for LEAD and CHD (including CHD morbidity and mortality). EDC subjects (332 men and 325 women), all diagnosed at Children's Hospital of Pittsburgh between 1950 and 1980, were first examined at baseline (1986-1988), and then biennially, for diabetes complications and their risk factors. Data used in the current analysis were from the first 6 years of follow-up, 98% provided at least some follow-up data for these analyses. CHD was defined as the presence of angina (diagnosed by the EDC examining physician) or a history of confirmed myocardial infarction or CHD death. An ankle-to-arm ratio of less than 0.9 at rest was considered to be evidence of LEAD. Among 635 subjects without CHD at baseline, 57 developed CHD (1.69/100 person-years), and among 579 without LEAD at baseline, 70 developed LEAD (2.31/100 person-years). CHD incidence rate was slightly higher in males, while LEAD incidence rate was slightly higher in females. Compared to non-incident cases, subjects who developed either complication were older, had a longer diabetes duration, higher LDL and total cholesterol, and were more likely to be hypertensive. In multivariate analyses, hypertension, low HDL cholesterol level, high white cell count, depression, and nephropathy were the independent risk factors for CHD (including morbidity and mortality). For LEAD, higher HbA1 level, higher LDL cholesterol level and smoking were the important contributing factors. In conclusion, the risk factor patterns differ between the two vascular complications. Glycemic control does not predict CHD overall but does predict LEAD, while hypertension and inflammatory markers are more closely related to CHD than to LEAD.

Persistent T cell anergy in human type 1 diabetes

An anergic phenotype has been observed in nonobese diabetic (NOD) mice and some autoreactive T cells from patients with type I diabetes. To better understand this phenomenon, we measured T cell proliferative responses to 10 diabetes-associated and up to 9 control Ags/peptides in 148 new diabetic children, 51 age- and MHC (DQ)-matched siblings (sibs), 31 patients with longstanding diabetes, and 40 healthy controls. Most (78-91%) patient and sib responses to glutamate decarboxylase of 65 kDa (GAD65), islet cell cytoplasmic autoantibody (ICA) 69, diabetes-associated T cell epitopes in ICA69 (Tep69), and heat shock protein (Hsp) 60 involved anergic T cells that required exogenous IL-2 to proliferate. Responses to proinsulin, IA-2 (and tetanus toxoid) required no IL-2 and generated sufficient cytokine to rescue anergic T cell responses. Most new patients (85%) had autoreactive T cells, three quarters targeting more than half of the diabetes Ags. Only 7.8% of the sibs and none of the controls had such multiple T cell autoreactivities, which thus characterize overt disease. Multiple anergic and nonanergic T cell autoreactivities were sustained during 2 yr follow-up after onset and in patients with longstanding (3-26 yr) diabetes. Activated patient T cells survived severe IL-2 deprivation, requiring 20-100 times less IL-2 than normal T cells to escape apoptosis. Diabetic T cell anergy thus persists for decades and is Ag and host specific but not related to disease course. Rescue by IL-2 from bystander T cells and high resistance to apoptosis may contribute to this persistence. These data explain some of the difficulties in the routine detection of disease-associated T cells, and they emphasize challenges for immunotherapy and islet transplantation.

Hypoglycemia in children with type 1 diabetes mellitus. Risk factors, cognitive function, and management

This article examines the relationship between hypoglycemia and brain function in children with type 1 diabetes. Hypoglycemic episodes occurring in the first 5 years of life may permanently disrupt cognitive function in a subset of children with diabetes, and a single acute episode of hypoglycemia may produce a transient reduction in mental efficiency, alter the electroencephalogram, and increase regional cerebral blood flow. Because iatrogenic development of hypoglycemic unawareness and autonomic failure are the most likely mediators of moderately severe hypoglycemia, medical management efforts should be directed at the prevention of frequently recurring, mild hypoglycemia.

Leukocyte adhesion deficiency type II

Leukocyte adhesion deficiency type II (LAD II) is a rare disorder characterized by recurrent infections, persistent leukocytosis, and severe mental and growth retardation. LAD II neutrophils are deficient in expression of selectin ligand activity, and exhibit a correspondingly diminished ability to roll on endothelium and to traffic to inflammatory sites in vivo. LAD II patients exhibit a deficiency in the expression of cell surface fucosylated glycan structures that include the H and Lewis blood group determinants and the sialyl Lewis x epitope, yet the corresponding fucosyltransferase activities responsible for synthesis of these structures are expressed at normal levels. The molecular defect in LAD II has been localized to the pathway that synthesizes GDP-fucose from GDP-mannose. However, the two known component enzymes in this GDP-fucose biosynthetic pathway are normal in sequence and in expression levels in LAD II cells. The genetic lesion in LAD II that accounts for the generalized fucosylation defect in LAD II patients remains to be determined.

Antibodies to oxidized LDL predict coronary artery disease in type 1 diabetes: a nested case-control study from the Pittsburgh Epidemiology of Diabetes Complications Study

The pathogenesis of excess cardiovascular risk in type 1 diabetes is unclear. LDL cholesterol is only weakly predictive, and its concentration is often normal in type 1 diabetes. We therefore examined whether markers of LDL oxidation such as antibodies to oxidized LDL (Ab-OxLDL) and LDL-containing immune complexes, rather than LDL concentration, were predictive of coronary artery disease (CAD) in type 1 diabetes. This nested case-control study from an epidemiologic cohort study included 49 incident cases of myocardial infarction (MI), angina, or CAD death and 49 age-, sex-, and duration-matched control subjects. Ab-OxLDL was measured by enzyme immunoassay and the apolipoprotein B (ApoB) content of immune complexes (ApoB-IC) precipitated by polyethylene glycol by immunoelectrophoresis in baseline stored samples. Ab-OxLDL was inversely, and ApoB-IC directly, related to subsequent CAD. In multivariate analyses, Ab-OxLDL remained a significant independent predictor along with previously recognized predictors, hypertension and Beck depression score. In conclusion, oxidation of LDL and the immune response it elicits may play a role in predicting the development of CAD in type 1 diabetes and explain at least some of the enhanced CAD risk in type I diabetes.

Leptin before and after insulin therapy in children with new-onset type 1 diabetes

Serum leptin levels reflect the amount of body fat. However, several reports suggest that insulin may also regulate serum leptin levels. This study was aimed at testing whether leptin levels are low in newly diagnosed patients with type 1 diabetes and increase after institution of insulin therapy. Nineteen children with new-onset type 1 diabetes were studied. Serum leptin levels were measured at presentation before insulin therapy was initiated (day 0), 1 day after insulin therapy (day 1), 3-5 days after insulin therapy (day 3-5), and at 3 months of follow-up (3 months). The control group consisted of 19 healthy children matched for age and body mass index. On day 0 leptin levels were lower in the patients compared with those in controls (3.3 +/- 0.2 vs. 6.2 +/- 0.9 ng/mL; P < 0.005). After insulin therapy, leptin levels increased significantly by day 1 without significant weight change and became comparable to control values by days 3-5. Before insulin therapy, leptin did not correlate with weight, body mass index, or hemoglobin A1c. After insulin therapy, leptin levels on days 3-5 correlated with insulin dose (r = 0.43; P = 0.03). The results of this study demonstrate that children with new-onset type 1 diabetes have low leptin levels before insulin therapy. Leptin levels increase within 24 h of insulin therapy and become comparable to nondiabetic levels by 3-5 days. This rapid increase in leptin after 24 h of insulinization is independent of changes in body weight and is postulated to be due to a stimulatory effect of insulin on leptin production, nutritional replenishment, or both factors together.

Transfection of adipocytes by gene gun-mediated transfer

Studies of the gene expression, metabolism and intracellular signaling of adipocytes have been hindered by the difficulty of transfecting cultured adipocytes using standard methods. Here, we demonstrate the utility of gene gun-mediated genetic transfer for transfection of differentiated 3T3-L1 adipocytes. Transfection of adipocytes with the Helios Gene Gun yielded a transfection efficiency that was consistently 5%-10% of total cells. We have used this technique to overexpress the transcription factor CCAAT/Enhancer Binding Protein alpha (C/EBP alpha) and transactivate an obese gene promoter-luciferase construct. This method has broad utility for transfection of other cell types that are resistant to transfection.

Gastroduodenal lesions in children with juvenile rheumatoid arthritis

BACKGROUND/AIMS

There are few studies about gastrointestinal abnormalities in patients with juvenile rheumatoid arthritis-probably due to the fact that this association is not frequently recognized. The aim of our study was to observe the prevalence of endoscopic gastroduodenal lesions in these patients.

METHODOLOGY

Fourteen patients with juvenile rheumatoid arthritis, all of them using non-steroidal anti-inflammatory drugs associated or not with methotrexate, were assessed clinically and by endoscopy. Gastric antrum biopsy and Helicobacter pylori search were also performed.

RESULTS

The mean age of the patients was 10.6 years (7 boys). Abdominal pain was observed in 27% of them. Macroscopic endoscopic lesions were found in 43% and infection by Helicobacter pylori in 57%. The correlation between anemia and endoscopic abnormalities was statistically significant (p < 0.05).

CONCLUSIONS

Our data show that patients with juvenile rheumatoid arthritis have considerable susceptibility to gastroduodenal lesions, especially if they are using any drug association and present anemia.

Antibodies to oxidized LDL and LDL-containing immune complexes as risk factors for coronary artery disease in diabetes mellitus

Several groups have published results from clinical studies supporting the involvement of anti-modified LDL antibodies as risk factors for the initiation or progression of cardiovascular disease. However, the data published so far are judged inconclusive because of several contradictory observations concerning the correlation between clinical evidence of arteriosclerosis and the levels of antibodies to oxidized LDL (oxLDL Ab). We have previously reported that oxLDL Ab exist both in free form and as antigen-antibody complexes (LDL-IC) in patients with insulin-dependent diabetes mellitus (IDDM). The presence of LDL-IC in IDDM patients has important implications: it may interfere with the assay of oxLDL antibodies and the levels of LDL-IC may correlate better with the development of arteriosclerosis than the levels of free oxLDL antibodies. To clarify these questions baseline samples collected from 49 IDDM patients, who subsequently developed coronary artery disease (CAD) during an 8-year follow-up period, were compared to baseline samples from 49 age-, sex-, and duration-matched control IDDM subjects who remained free of clinical CAD during an identical follow-up period. The levels of free oxLDL antibody were significantly lower in the patients who developed CAD. The same patients had significantly higher concentrations of total cholesterol, apolipoprotein B, and IgA in immune complex-enriched polyethylene glycol (PEG) precipitates. The concentration of IgG was also higher in PEG precipitates from patients who developed CAD, but did not reach statistical significance. This indicates that patients who develop CAD had higher levels of circulating LDL-IC, a fact that could not be deduced from the measurement of free oxLDL antibody concentrations. A linear regression analysis of the correlation between the concentrations of total cholesterol in PEG precipitates, taken as a surrogate measurement of PEG-precipitated oxLDL-IC, and the concentration of free oxLDL antibody in serum showed a statistically significant negative correlation (r = -0.229, P = 0. 024). Our results support the conclusion that oxLDL-IC may be a risk factor for the development of macrovascular disease in IDDM patients. We also have demonstrated that circulating oxLDL-IC interfere with the assay of free oxLDL antibodies.

The association between a family history of type 2 diabetes and coronary artery disease in a type 1 diabetes population

OBJECTIVE

To examine whether a potential marker for type 2 diabetes (family history) is related to CAD in type 1 diabetic subjects. The two major types of primary diabetes, type 1 and type 2, are both associated with an increased risk of developing coronary artery disease (CAD). However, the etiology and associated risk factors may differ by type of diabetes. In type 2 diabetes, CAD is likely to be linked with the insulin resistance associated with the type 2 "process," while CAD in type 1 diabetes has, so far, been more closely linked to renal disease. Because the etiologies of type 1 and type 2 diabetes are different, it is possible that some CAD in type 1 diabetes may be related to the coexistence of type 2 diabetes susceptibility (i.e., insulin resistance).

RESEARCH DESIGN AND METHODS

We evaluated the interrelationships between family history of type 2 diabetes (age at onset > 30 years, no insulin for 1st year) and presence of CAD in a cohort of childhood-onset type 1 diabetic subjects using the Pittsburgh Epidemiology of Diabetes Complications study (n = 658).

RESULTS

A first-degree family history of type 2 diabetes was reported in 112 subjects, and CAD was present in 119 subjects. Those subjects reporting a family history of type 2 diabetes were significantly older, had a longer duration of type 1 diabetes, had higher triglyceride and LDL cholesterol levels, and had a borderline significantly increased Beck depression inventory. Sex differences in CAD risk factors were also noted. Using logistic regression analysis, the odds ratio (95% CI) for the presence of CAD in association with a family history of NIDDM was 1.89 (1.27-2.84). The odds ratio (95% CI) after adjusting for disease duration, triglycerides, hypertension, Beck depression, and nephropathy status was 1.45 (0.87-2.28).

CONCLUSIONS

We conclude that a family history of type 2 diabetes is a risk factor for CAD in type 1 diabetic subjects. This supports the concept that insulin resistance may contribute to development of CAD in type 1 diabetes.

Combined analysis of GAD65 and ICA512(IA-2) autoantibodies in organ and non-organ-specific autoimmune diseases confers high specificity for insulin-dependent diabetes mellitus

There is evidence that insulin-dependent diabetes mellitus (IDDM) may develop in association with other non-beta-cell-specific autoimmune diseases. We aimed to assess whether autoantibodies to the islet cell antigens glutamic acid decarboxylase (Mr 65,000 isoform) (GAD65) and ICA512(IA-2), present alone or in combination, are limited to IDDM or also occur in other organ- or non-organ-specific autoimmune disorders. We determined the frequency of these autoantibodies by radioimmunoassay in 199 sera from patients with autoimmune thyroid diseases (AITD), rheumatoid arthritis (RA), systemic lupus erythematosus (SLE) and primary biliary cirrhosis (PBC), and compared the results with those from 507 newly diagnosed patients with IDDM and 280 healthy controls. ICA512(IA-2) autoantibodies were detected exclusively in AITD with concurrent IDDM, but not in other autoimmune diseases without IDDM, whereas GAD65 autoantibodies exceeded the limit of normal in 67.7% (21 of 31) of patients with AITD who also had IDDM and in 5.5% (three of 55) of patients with PBC. The frequency of either GAD65 and/or ICA512(IA-2) autoantibodies was significantly higher in patients with AITD who also had IDDM (27 of 31, 87.1%) than in those with AITD alone (one of 53, 1.9%; P<10(-6)), but was not significantly different from those patients with newly diagnosed IDDM (418 of 507, 82.4%). Neither patients with organ- or non-organ-specific autoimmune diseases without IDDM nor healthy controls had autoantibodies against both GAD65 and ICA512(IA-2). Despite the fact that one of the two autoantibodies was occasionally detected in patients with non-beta-cell-specific autoimmune diseases without IDDM, combined determination of GAD65 and ICA512(IA-2) autoantibodies specifically identified IDDM in the majority of patients with AITD. In conclusion, because of the strong association of IDDM with AITD, testing for multiple islet autoanti-bodies could be useful as a predictive marker for risk of progression to IDDM onset amongst patients with autoimmune thyroid disorders.

Improvement of glucose homeostasis and hepatic insulin resistance in ob/ob mice given oral molybdate

Molybdate (Mo) exerts insulinomimetic effects in vitro. In this study, we evaluated whether Mo can improve glucose homeostasis in genetically obese, insulin-resistant ob/ob mice. Oral administration of Mo (174 mg/kg molybdenum element) for 7 weeks did not affect body weight, but decreased the hyperglycaemia (approximately 20 mM) of obese mice to the levels of lean (L) (+/+) mice, and reduced the hyperinsulinaemia to one-sixth of pretreatment levels. Tolerance to oral glucose was improved: total glucose area was 30% lower in Mo-treated mice than in untreated ob/ob mice (O), while the total insulin area was halved. Hepatic glucokinase (GK) mRNA level and activity were unchanged in O mice compared with L mice, but the mRNA level and activity of L-type pyruvate kinase (L-PK) were increased in O mice by 3.5- and 1.7-fold respectively. Mo treatment increased GK mRNA levels and activity (by approximately 2.2-fold and 61% compared with O values), and had no, or only a mild, effect on the already increased L-PK variables. mRNA levels and activity of the gluconeogenic enzyme, phosphoenolpyruvate carboxykinase (PEPCK) were augmented in O liver (sixfold and by 57% respectively), and these were reduced by Mo treatment. Insulin binding to partially purified receptors from liver was reduced in O mice and restored by Mo treatment. Despite this correction, overall receptor tyrosine kinase activity was not improved in Mo mice. Moreover, the overexpression (by two- to fourfold) of the cytokine tumour necrosis factor alpha (TNF alpha) in white adipose tissue, which may have a determinant role in the insulin resistance of the O mice, was unaffected by Mo. Likewise, overexpression of the ob gene in white adipose tissue was unchanged by Mo. In conclusion, Mo markedly improved glucose homeostasis in the ob/ob mice by an insulin-like action which appeared to be exerted distal to the insulin receptor tyrosine kinase step. The blood glucose-lowering effect of Mo was unrelated to over-expression of the TNF alpha and ob genes in O mice, but resulted at least in part from attenuation of liver insulin resistance by the reversal of pre-translational regulatory defects in these mice.

Cumulative glycemic exposure and microvascular complications in insulin-dependent diabetes mellitus. The glycemic threshold revisited

BACKGROUND

The development of microvascular insulin-dependent diabetes mellitus (IDDM) complications has been shown to be related to both duration of diabetes and the degree of glycemic exposure. However, controversy exists as to whether there is a threshold of glycemic exposure, below which there is minimal risk. Furthermore, there are few data describing the relationship of total glycemic exposure (duration x degree) to complications rates-a potentially useful research and clinical tool.

OBJECTIVES

To determine a cumulative glycemic exposure variable that combines the effect of both degree and duration of hyperglycemia and to evaluate this variable in terms of its relation to microvascular complications. The association between cumulative glycemic exposure and complication risk was also examined to evaluate whether there was a threshold effect.

METHODS

A total of 353 patients with IDDM who had completed the first 6 years of follow-up in the Pittsburgh Epidemiology of Diabetes Complications Study were included in this analysis. These subjects had a mean age of 27.9 years, and the mean duration of the disease was 19.4 years. Subjects were examined at baseline (cycle 1) and then biennially (cycle 2, cycle 3, and cycle 4) for diabetes complications. Total glycosylated hemoglobin (HbA1) was measured at each cycle. A cumulative glycemic exposure variable, named A1months, was calculated by multiplying the number of HbA1 units above normal at each cycle by the number of months between the midpoints of the preceding and succeeding cycle intervals.

RESULTS

The mean number of A1months experienced at the time of diagnosis of proliferative retinopathy (914), microalbuminuria (952), overt nephropathy (1043), and distal symmetrical polyneuropathy (1043) did not vary by duration of diabetes. Thus, approximately 1000 A1months were needed (on average) for the advanced complications to develop. Although the risk for developing proliferative retinopathy rose gradually as A1months increased, a more abrupt increase in the risk was seen (again at approximately 1000 A1months) for microalbuminuria (odds ratio, 6.9; 95% confidence interval, 2.5-19.1), overt nephropathy (odds ratio, 6.5; 95% confidence interval, 2.0-21.7), and distal symmetrical polyneuropathy (odds ratio, 6.5; 95% confidence interval, 2.4-17.8). Nonetheless, complications developed in the majority of cases at glycemic exposures below 1000 A1months. The cumulative glycemic exposure variable A1months does not predict complications any better than its component variables (duration and HbA1). Furthermore, formal statistical testing failed to show a definitive threshold for any complication.

CONCLUSIONS

Although A1months does not enhance prediction of complications, it may be a useful summary measure of glycemic exposure for both patients and physicians. However, although subjects with 1000 A1months or more appear to be at increased risk of developing most microvascular complications, because the majority of complications arise in subjects with less than this exposure, this threshold value should only be considered a minimal goal. For example, our data suggest that for most microvascular complications to develop, it would take, on average, 83 years with an HbA1 unit at 1% above normal, 42 years at 2% above normal, 28 years at 3% above normal. 21 years at 4% above normal, and 18 years at 5% above normal.

Health insurance and the financial impact of IDDM in families with a child with IDDM

OBJECTIVE

To examine the health insurance experience and out-of-pocket health care costs of families with a child with IDDM.

RESEARCH DESIGN AND METHODS

A case-control study of 197 families with a child with IDDM and 142 control families with no diabetic children was conducted. IDDM-affected families were identified from the Allegheny County IDDM Registry. Brothers and sisters of the parents in the IDDM-affected families were asked to participate as control subjects. Health insurance coverage and the money that families spent on health care services and supplies not reimbursed by insurance (out-of-pocket costs) were assessed by questionnaire.

RESULTS

No difference was found between the IDDM-affected and control families in the percentages with or without insurance. Families with low household incomes ($10,000-$19,999) were at the greatest risk for having no insurance. While coverage provided by private plans was similar between the IDDM-affected and control families, many families had no reimbursement for insulin (10%), syringes (10%), or blood testing strips (30%). Out-of-pocket expenses were 56% higher in the IDDM-affected families than in the control families. Seventeen percent of the IDDM-affected families had expenses over 10% of their household income. This particularly affected families with low household incomes. Pre-existing illness clauses and insurance denial affected only a small proportion of the case families.

CONCLUSIONS

These data illustrate that most families with a child with IDDM have health insurance, yet still incur larger out-of-pocket health care costs than do families without the presence of diabetes. IDDM-affected families likely face a number of economic decisions regarding health insurance and the use of health care.

Hypertension as a risk factor for diabetic neuropathy: a prospective study

The pathogeneses of diabetic neuropathy is still unclear. This study prospectively investigated the risk factors for distal symmetrical polyneuropathy (DSP) in a cohort of childhood-onset IDDM patients. Subjects from the Epidemiology of Diabetes Complications (EDC) Study were clinically examined at baseline and then biennially. DSP was diagnosed by a combination of clinical criteria, symptoms and signs (Diabetes Control and Complications Trial [DCCT] exam), and quantitative sensory threshold (QST). Among the 463 (70.4%) subjects who were free of DSP at baseline, 453 (97.8%) participated in at least one biennial reexamination during the first 6 years of follow-up and were included in the current analysis. A total of 68 (15.0%) subjects developed DSP in 6 years, giving a cumulative probability of 0.29. The Cox proportional hazards model shows that longer IDDM duration, hypertension, poor glycemic control, height, and smoking were all independent predictors of the incidence of DSP (all P < 0.0001, except for smoking for which P = 0.03). Hypertension showed the greatest impact on the development of DSP for individuals with either short or long IDDM duration. This study confirms some risk factors for DSP found in cross-sectional studies and suggests a strong relationship between hypertension and DSP. The results indicate that in addition to good glycemic control, avoidance of smoking and good blood pressure control may be helpful in preventing or delaying the onset of DSP in IDDM patients.

Developmental and nutritional changes of ob and PPAR gamma 2 gene expression in rat white adipose tissue

The ob gene encodes leptin, a hormone which induces satiety and increases energy expenditure. The peroxisome proliferator-activated receptor gamma 2 isoform (PPAR gamma 2) gene encodes a transcription factor which controls adipocyte differentiation and expression of fat-specific genes. We have studied the regulation of these two genes in white adipose tissue (WAT) during the suckling-weaning transition. Suckling rats ingest a high-fat diet (milk). Fat-pad weight barely varied during the last week of suckling. ob mRNA levels, which were very low in 15-day-old rats, rose approximately 6-fold until weaning at 21 days. When the rats were weaned on to a standard (high-carbohydrate) laboratory chow, epididymal WAT enlarged approximately 7-fold, and ob mRNA kept increasing progressively and doubled between 21 and 30 days. This evolution contrasted with that of fatty acid synthase (FAS) mRNA, which increased sharply, but only after weaning. To distinguish between the influence of developmental and nutritional factors on ob expression, a group of rats was weaned on to a high-fat diet. This prevented the rise in glycaemia and insulinaemia and the decrease in plasma non-esterified fatty acids which otherwise occurred at weaning. This also resulted in a slight (10-15%) decrease in food intake and body weight gain. Under this high-fat diet, the rise of ob mRNA in WAT was augmented (3.7-fold in 30- versus 21-day-old pups), whereas the normal rise in FAS mRNA levels was attenuated. Fat-pad weights and adipocyte cell size and number were roughly similar in high-carbohydrate- and high-fat-weaned pups. mRNA levels of PPAR gamma 2, like those of ob, were low in the WAT of 15-day-old suckling pups, doubled at 21 days, and reached a maximum as soon as 23 days. This evolution further differed from that of ob mRNA in not being influenced by diet composition. In conclusion, ob expression markedly increases during the suckling-weaning transition, and this effect is accentuated by a high-fat diet. Qualitative nutritional changes in ob mRNA were correlated with neither acute changes in adipose-tissue mass, nor cell size/number, nor variations in insulinaemia. PPAR gamma 2 also increased during suckling, but rapidly reached a plateau after weaning and no longer changed thereafter. Unlike ob, PPAR gamma 2 was not influenced by the diet composition.

Employment patterns among parents of children with insulin-dependent diabetes mellitus (IDDM)

OBJECTIVE

To examine the influence of diabetes on the employment patterns of parents of children living with diabetes.

STUDY DESIGN

A case-control study of 197 families with an IDDM child and 142 control families without IDDM children was conducted. Case families were identified from a population-based diabetes registry. Brothers and sisters of the parents in the IDDM families were asked to participate as controls. Employment rates, absenteeism related to child care, and changes in work status were assessed by means of a questionnaire. Surveys were obtained from 85% of the families (172 case; 118 control).

RESULTS

No difference was found between the IDDM and control families in the overall rate of employment and changes in work patterns. However, IDDM families were more likely to report absences from work related to child care (58% vs. 45%, P < 0.05). This impact was greatest for the working mothers. The greatest impact of IDDM on employment may be faced by single parents, who reported lower rates of employment and higher rates of absenteeism and changes in work patterns.

CONCLUSIONS

Families face decisions regarding employment and the appropriate level of care for children with diabetes. These data illustrate that most families with an IDDM child have employment experiences similar to those of families without diabetic children. Larger sample sizes of single parent families are necessary to confirm these findings.

The dietary intake of children with IDDM

OBJECTIVE

To assess the dietary intake of children with IDDM and to determine whether the intake meets the current nutritional recommendations for children with IDDM.

RESEARCH DESIGN AND METHODS

A total of 66 children with IDDM who were < 10 years of age were recruited from two suburban Pennsylvania hospitals. To collect dietary intake data, subjects were asked, via telephone interview, to complete three random-day 24-h dietary recalls. Data were analyzed for the content of nutrients and other food components by a computerized database program. Intakes were expressed as a 3-day average intake for each subject.

RESULTS

Overall mean intake of protein and cholesterol approximated the current recommendations. The mean intake of saturated fat exceeded recommendations, while fiber intake was less than the recommended level. Many of the children consumed levels of saturated fat well above recommendations. Energy, vitamin, and mineral intakes were adequate for the overall sample. However, from 10 to 40% of the sample had an inadequate intake of vitamin D, vitamin E, and zinc. The percentage of those with inadequate intakes of these nutrients decreased with age.

CONCLUSIONS

These data suggest that, on average, among this sample of children with IDDM aged < 10 years, adherence to the current nutritional recommendations for children with IDDM was adequate, but some individual children had intakes that were not consistent with the recommendations for optimal management of IDDM.

The changing course of diabetic nephropathy: low-density lipoprotein cholesterol and blood pressure correlate with regression of proteinuria

Diabetic nephropathy (DN) as manifested by persistent and clinically evident proteinuria, has long been considered an irreversible process that predicts a rapid decline in renal function. The observation of reversal of DN in several individuals enrolled in a prospective study of the natural course of diabetes complications challenged this view and led to the current investigation into the correlates of such regression of proteinuria. DN was defined as a median albumin excretion rate (AER) over 200 microg/min in two or three urine collections obtained at baseline, and again at 2 and 4 years of follow-up. Among 658 individuals with childhood-onset insulin-dependent diabetes mellitus (IDDM), 146 had DN at baseline. Nine subsequently died without renal failure, and 13 were lost to follow-up. Of the 124 subjects with at least survey follow-up data, 32 (24%) developed renal failure, and 78 of the remaining 92 provided full quantitative data. AER decreased by > or = 10-fold into the microalbuminuric (20 to 200 microg/min) or normal range (<20 microg/min) in 7 of these individuals and are called "regressors of proteinuria." Compared with the remaining 71 subjects, the strongest correlate of regression of proteinuria was an improvement in fasting plasma low-density lipoprotein cholesterol (LDL-C) in the 7 regressors (P < 0.008). Improved glycemic control was not a significant predictor of improved AER. Five of the 7 individuals with improved AER had a baseline median AER below 500 microg/min. When the 7 regressors of proteinuria were combined with an additional 38 individuals who also experienced smaller decreases in median AER, such improvement was associated with a more favorable systolic (or diastolic) blood pressure (BP) change (P < 0.01), and a decrease in plasma LDL-C level (P = 0.01). These data suggest that proteinuria in DN may substantially regress in approximately 6% and improve in at least 34% of individuals with IDDM over a 4-year period, often in association with a decrease in plasma LDL-C concentration or stabilization or improvement in BP. Furthermore, the data suggest that the nonreversibility threshold for diabetic nephropathy may be higher (500 mg/min) than previously reported (200 microg/min).