Sudden death in type 1 diabetes

Near-sudden unexpected death in a patient with epilepsy undergoing hemodialysis: a case report

Sudden unexpected death in epilepsy (SUDEP) has been defined as a sudden/unexpected, witnessed/unwitnessed, nontraumatic, and nondrowning death in epileptic patients with/without seizure evidence and documented status epilepticus. Identified as the leading cause of epilepsy-related deaths, SUDEP cases are highly unrecognized and underreported due to diagnostic difficulty. We report a case of a successfully revived hemodialysis patient who developed cardiopulmonary arrest after a witnessed convulsive seizure. Electroencephalogram revealed epileptic abnormalities. Therefore, this case could be seizure-induced cardiopulmonary arrest and near-SUDEP. Hence, the possibility of SUDEP should be considered even in hemodialysis patients having conventional coronary risk factors for sudden cardiac death.

Can dynamic and static pupillary responses be used as an indicator of autonomic dysfunction in patients with obstructive sleep apnea syndrome?

PURPOSE

We aimed to reveal whether static and dynamic pupillary responses can be used for the detection of autonomic nervous system (ANS) dysfunction in patients with obstructive sleep apnea syndrome (OSAS).

METHODS

We included in this study patients with OSAS, who were divided into three groups according to the apnea-hypopnea index (AHI) (group 1, mild [n = 20]; group 2, moderate [n = 20]; and group 3, severe [n = 20]), and healthy controls (group 4, n = 20). Pupillary responses were measured using a pupillometry system.

RESULTS

Static (mesopic PD, P = 0.0019; low photopic PD, P = 0.001) and dynamic pupil responses (resting diameter, P = 0.004; amplitude of pupil contraction, P < 0.001; duration of pupil contraction, P = 0.022; velocity of pupil contraction, P = 0.001; and velocity of pupil dilation, P = 0.012) were affected in patients with different OSAS severities. Also, AHI was negatively correlated with mesopic PD (P = 0.008), low photopic PD (P = 0.003), resting diameter (P = 0.001), amplitude of pupil contraction (P < 0.001), duration of pupil contraction (P = 0.011), velocity of pupil contraction (P < 0.001), and velocity of pupil dilation (P = 0.001).

CONCLUSION

We detected pupil responses innervated by the ANS were affected in the OSAS patients. This effect was more significant in the severe OSAS patients. Therefore, the pupillometry system can be an easily applicable, noninvasive method to detect ANS dysfunction in the OSA patients.

Continuous Glucose and Heart Rate Monitoring in Young People with Type 1 Diabetes: An Exploratory Study about Perspectives in Nocturnal Hypoglycemia Detection

A combination of information from blood glucose (BG) and heart rate (HR) measurements has been proposed to investigate the HR changes related to nocturnal hypoglycemia (NH) episodes in pediatric subjects with type 1 diabetes (T1D), examining whether they could improve hypoglycemia prediction. We enrolled seventeen children and adolescents with T1D, monitored on average for 194 days. BG was detected by flash glucose monitoring devices, and HR was measured by wrist-worn fitness trackers. For each subject, we compared HR values recorded in the hour before NH episodes (before-hypoglycemia) with HR values recorded during sleep intervals without hypoglycemia (no-hypoglycemia). Furthermore, we investigated the behavior after the end of NH. Nine participants (53%) experienced at least three NH. Among these nine subjects, six (67%) showed a statistically significant difference between the before-hypoglycemia HR distribution and the no-hypoglycemia HR distribution. In all these six cases, the before-hypoglycemia HR median value was higher than the no-hypoglycemia HR median value. In almost all cases, HR values after the end of hypoglycemia remained higher compared to no-hypoglycemia sleep intervals. This exploratory study support that HR modifications occur during NH in T1D subjects. The identification of specific HR patterns can be helpful to improve NH detection and prevent fatal events.

Transgenic Rabbit Models in Proarrhythmia Research

Drug-induced proarrhythmia constitutes a potentially lethal side effect of various drugs. Most often, this proarrhythmia is mechanistically linked to the drug's potential to interact with repolarizing cardiac ion channels causing a prolongation of the QT interval in the ECG. Despite sophisticated screening approaches during drug development, reliable prediction of proarrhythmia remains very challenging. Although drug-induced long-QT-related proarrhythmia is often favored by conditions or diseases that impair the individual's repolarization reserve, most cellular, tissue, and whole animal model systems used for drug safety screening are based on normal, healthy models. In recent years, several transgenic rabbit models for different types of long QT syndromes (LQTS) with differences in the extent of impairment in repolarization reserve have been generated. These might be useful for screening/prediction of a drug's potential for long-QT-related proarrhythmia, particularly as different repolarizing cardiac ion channels are impaired in the different models. In this review, we summarize the electrophysiological characteristics of the available transgenic LQTS rabbit models, and the pharmacological proof-of-principle studies that have been performed with these models—highlighting the advantages and disadvantages of LQTS models for proarrhythmia research. In the end, we give an outlook on potential future directions and novel models.

The Yin and Yang Between Plasma Glucose Levels and Cortisol Replacement Therapy in Schmidt's Syndrome

Objective: To illustrate how steroid replacement in adrenal insufficiency can influence the development of hypoglycemia in a patient with type 1 diabetes mellitus (T1D). Methods: We describe the case of a 36-year-old female patient with T1D and Addison's disease (Schmidt's syndrome) on multiple daily insulin injections who presented with recurrent hypoglycemia despite being on physiological replacement doses of hydrocortisone. Results: With the assistance of continuous glucose monitoring technology, a pattern of nocturnal hypoglycemia was clearly identified. The patient was taking her hydrocortisone 15 mg in the morning and 5 mg in the early afternoon. With the short half-life of oral hydrocortisone, the evening decline in plasma cortisol concentration led to an increased susceptibility to recurrent evening and nocturnal hypoglycemia. Hypoglycemic episodes were resolved when her morning hydrocortisone dose was changed and prednisolone was added to a later time in the evening. Conclusion: Patients with Schmidt's syndrome can be susceptible to nocturnal hypoglycemia with inadequate steroid replacement. Identifying patients at risk for hypoglycemia in Schmidt's syndrome provides an opportunity for precision management beyond the manipulation of antihyperglycemic agents.

Hyperglycemia induces defective Ca2+ homeostasis in cardiomyocytes

Diabetes and other metabolic conditions characterized by elevated blood glucose constitute important risk factors for cardiovascular disease. Hyperglycemia targets myocardial cells rendering ineffective mechanical properties of the heart, but cellular alterations dictating the progressive deterioration of cardiac function with metabolic disorders remain to be clarified. In the current study, we examined the effects of hyperglycemia on cardiac function and myocyte physiology by employing mice with high blood glucose induced by administration of streptozotocin, a compound toxic to insulin-producing β-cells. We found that hyperglycemia initially delayed the electrical recovery of the heart, whereas cardiac function became defective only after ~2 mo with this condition and gradually worsened with time. Prolonged hyperglycemia was associated with increased chamber dilation, thinning of the left ventricle (LV), and myocyte loss. Cardiomyocytes from hyperglycemic mice exhibited defective Ca²⁺ transients before the appearance of LV systolic defects. Alterations in Ca²⁺ transients involved enhanced spontaneous Ca²⁺ releases from the sarcoplasmic reticulum (SR), reduced cytoplasmic Ca²⁺ clearance, and declined SR Ca²⁺ load. These defects have important consequences on myocyte contraction, relaxation, and mechanisms of rate adaptation. Collectively, our data indicate that hyperglycemia alters intracellular Ca²⁺ homeostasis in cardiomyocytes, hindering contractile activity and contributing to the manifestation of the diabetic cardiomyopathy.

NEW & NOTEWORTHY

We have investigated the effects of hyperglycemia on cardiomyocyte physiology and ventricular function. Our results indicate that defective Ca²⁺ handling is a critical component of the progressive deterioration of cardiac performance of the diabetic heart.

Rabbit models as tools for preclinical cardiac electrophysiological safety testing: Importance of repolarization reserve

It is essential to more reliably assess the pro-arrhythmic liability of compounds in development. Current guidelines for pre-clinical and clinical testing of drug candidates advocate the use of healthy animals/tissues and healthy individuals and focus on the test compound's ability to block the hERG current and prolong cardiac ventricular repolarization. Also, pre-clinical safety tests utilize several species commonly used in cardiac electrophysiological studies. In this review, important species differences in cardiac ventricular repolarizing ion currents are considered, followed by the discussion on electrical remodeling associated with chronic cardiovascular diseases that leads to altered ion channel and transporter expression and densities in pathological settings. We argue that the choice of species strongly influences experimental outcome and extrapolation of results to human clinical settings. We suggest that based on cardiac cellular electrophysiology, the rabbit is a useful species for pharmacological pro-arrhythmic investigations. In addition to healthy animals and tissues, the use of animal models (e.g. those with impaired repolarization reserve) is suggested that more closely resemble subsets of patients exhibiting increased vulnerability towards the development of ventricular arrhythmias and sudden cardiac death.

Reduction in Kv Current Enhances the Temporal Dispersion of the Action Potential in Diabetic Myocytes: Insights From a Novel Repolarization Algorithm

BACKGROUND

Diabetes is associated with prolongation of the QT interval of the electrocardiogram and enhanced dispersion of ventricular repolarization, factors that, together with atherosclerosis and myocardial ischemia, may promote the occurrence of electrical disorders. Thus, we tested the possibility that alterations in transmembrane ionic currents reduce the repolarization reserve of myocytes, leading to action potential (AP) prolongation and enhanced beat-to-beat variability of repolarization.

METHODS AND RESULTS

Diabetes was induced in mice with streptozotocin (STZ), and effects of hyperglycemia on electrical properties of whole heart and myocytes were studied with respect to an untreated control group (Ctrl) using electrocardiographic recordings in vivo, ex vivo perfused hearts, and single-cell patch-clamp analysis. Additionally, a newly developed algorithm was introduced to obtain detailed information of the impact of high glucose on AP profile. Compared to Ctrl, hyperglycemia in STZ-treated animals was coupled with prolongation of the QT interval, enhanced temporal dispersion of electrical recovery, and susceptibility to ventricular arrhythmias, defects observed, in part, in the Akita mutant mouse model of type I diabetes. AP was prolonged and beat-to-beat variability of repolarization was enhanced in diabetic myocytes, with respect to Ctrl cells. Density of Kv K(+) and L-type Ca(2+) currents were decreased in STZ myocytes, in comparison to cells from normoglycemic mice. Pharmacological reduction of Kv currents in Ctrl cells lengthened AP duration and increased temporal dispersion of repolarization, reiterating features identified in diabetic myocytes.

CONCLUSIONS

Reductions in the repolarizing K(+) currents may contribute to electrical disturbances of the diabetic heart.

Hypo- and Hyperglycemic Alarms: Devices and Algorithms

Soon after the discovery that insulin regulates blood glucose by Banting and Best in 1922, the symptoms and risks associated with hypoglycemia became widely recognized. This article reviews devices to warn individuals of impending hypo- and hyperglycemia; biosignals used by these devices include electroencephalography, electrocardiography, skin galvanic resistance, diabetes alert dogs, and continuous glucose monitors (CGMs). While systems based on other technology are increasing in performance and decreasing in size, CGM technology remains the best method for both reactive and predictive alarming of hypo- or hyperglycemia.

Severe hypoglycemia-induced lethal cardiac arrhythmias are mediated by sympathoadrenal activation

For people with insulin-treated diabetes, severe hypoglycemia can be lethal, though potential mechanisms involved are poorly understood. To investigate how severe hypoglycemia can be fatal, hyperinsulinemic, severe hypoglycemic (10-15 mg/dL) clamps were performed in Sprague-Dawley rats with simultaneous electrocardiogram monitoring. With goals of reducing hypoglycemia-induced mortality, the hypotheses tested were that: 1) antecedent glycemic control impacts mortality associated with severe hypoglycemia; 2) with limitation of hypokalemia, potassium supplementation could limit hypoglycemia-associated deaths; 3) with prevention of central neuroglycopenia, brain glucose infusion could prevent hypoglycemia-associated arrhythmias and deaths; and 4) with limitation of sympathoadrenal activation, adrenergic blockers could prevent hypoglycemia-induced arrhythmic deaths. Severe hypoglycemia-induced mortality was noted to be worsened by diabetes, but recurrent antecedent hypoglycemia markedly improved the ability to survive an episode of severe hypoglycemia. Potassium supplementation tended to reduce mortality. Severe hypoglycemia caused numerous cardiac arrhythmias including premature ventricular contractions, tachycardia, and high-degree heart block. Intracerebroventricular glucose infusion reduced severe hypoglycemia-induced arrhythmias and overall mortality. β-Adrenergic blockade markedly reduced cardiac arrhythmias and completely abrogated deaths due to severe hypoglycemia. Under conditions studied, sudden deaths caused by insulin-induced severe hypoglycemia were mediated by lethal cardiac arrhythmias triggered by brain neuroglycopenia and the marked sympathoadrenal response.

Glutathione oxidation unmasks proarrhythmic vulnerability of chronically hyperglycemic guinea pigs

Chronic hyperglycemia in type-1 diabetes mellitus is associated with oxidative stress (OS) and sudden death. Mechanistic links remain unclear. We investigated changes in electrophysiological (EP) properties in a model of chronic hyperglycemia before and after challenge with OS by GSH oxidation and tested reversibility of EP remodeling by insulin. Guinea pigs survived for 1 mo following streptozotocin (STZ) or saline (sham) injection. A treatment group received daily insulin for 2 wk to reverse STZ-induced hyperglycemia (STZ + Ins). EP properties were measured using high-resolution optical action potential mapping before and after challenge of hearts with diamide. Despite elevation of glucose levels in STZ compared with sham-operated (P = 0.004) and STZ + Ins (P = 0.002) animals, average action potential duration (APD) and arrhythmia propensity were not altered at baseline. Diamide promoted early (<10 min) formation of arrhythmic triggers reflected by a higher arrhythmia scoring index in STZ (P = 0.045) and STZ + Ins (P = 0.033) hearts compared with sham-operated hearts. APD heterogeneity underwent a more pronounced increase in response to diamide in STZ and STZ + Ins hearts compared with sham-operated hearts. Within 30 min, diamide resulted in spontaneous incidence of ventricular tachycardia and ventricular fibrillation (VT/VF) in 3/6, 2/5, 1/5, and 0/4 STZ, STZ + Ins, sham-operated, and normal hearts, respectively. Hearts prone to VT/VF exhibited greater APD heterogeneity (P = 0.010) compared with their VT/VF-free counterparts. Finally, altered EP properties in STZ were not rescued by insulin. In conclusion, GSH oxidation enhances APD heterogeneity and increases arrhythmia scoring index in a guinea pig model of chronic hyperglycemia. Despite normalization of glycemic levels by insulin, these proarrhythmic properties are not reversed, suggesting the importance of targeting antioxidant defenses for arrhythmia suppression.

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.

Confirmation of hypoglycemia in the "dead-in-bed" syndrome, as captured by a retrospective continuous glucose monitoring system

OBJECTIVE

To report a case that substantiates the presence of hypoglycemia at the time of death of a young man with type 1 diabetes, who was found unresponsive in his undisturbed bed in the morning.

METHODS

We describe a 23-year-old man with a history of type 1 diabetes treated with an insulin pump, who had recurrent severe hypoglycemia. In an effort to understand these episodes better and attempt to eliminate them, a retrospective (non-real-time) continuous subcutaneous glucose monitoring system (CGMS) was attached to the patient. He was found dead in his undisturbed bed 20 hours later. The insulin pump and CGMS were both downloaded for postmortem study.

RESULTS

Postmortem download of the data in the CGMS demonstrated glucose levels below 30 mg/dL around the time of his death, with only a minimal counter-regulatory response. This finding corresponded to a postmortem vitreous humor glucose of 25 mg/dL. An autopsy showed no major anatomic abnormalities that could have contributed to his death.

CONCLUSION

To our knowledge, this is the first documentation of hypoglycemia at the time of death in a patient with the "dead-in-bed" syndrome. This report should raise the awareness of physicians to the potentially lethal effects of hypoglycemia and provide justification for efforts directed at avoiding nocturnal hypoglycemia.

Sudden adult death

In the investigation of sudden death in adults, channelopathies, such as long QT syndrome, have risen to the fore in the minds of forensic pathologists in recent years. Examples of these disorders are touched upon in this review as an absence of abnormal findings at postmortem examination is characteristic and the importance of considering the diagnosis lies in the heritable nature of these conditions. Typically, a diagnosis of a possible channelopathy is evoked as an explanation for a 'negative autopsy' in a case of apparent sudden natural death. However, the one potential adverse effect of this approach is that subtle causes of sudden death may be overlooked. The intention of this article is to review and discuss potential causes of sudden adult death (mostly natural) that should be considered before resorting to a diagnosis of possible channelopathy. Nonetheless, it becomes apparent that many of the potential causes of sudden death can have a genetic basis. Thus, it becomes an important consideration that there may be a genetic basis to sudden death that extends beyond the negative autopsy.

Reduced volume-regulated outwardly rectifying anion channel activity in ventricular myocyte of type 1 diabetic mice

The currents through the volume-regulated outwardly rectifying anion channel (VRAC) were measured in single ventricular myocytes obtained from streptozotocin (STZ)-induced diabetic mice, using whole-cell voltage-clamp method. In myocytes from STZ-diabetic mice, the density of VRAC current induced by hypotonic perfusion was markedly reduced, compared with that in the cells form normal control mice. Video-image analysis showed that the regulatory volume decrease (RVD), which was seen in normal cells after osmotic swelling, was almost lost in myocytes from STZ-diabetic mice. Some mice were pretreated with 3-O-methylglucose before STZ injection, to prevent the STZ's beta cell toxicity. In the myocytes obtained from such mice, the magnitude of VRAC current and the degree of RVD seen during hypotonic challenge were almost normal. Incubation of the myocytes from STZ-diabetic mice with insulin reversed the attenuation of VRAC current. These findings suggested that the STZ-induced chronic insulin-deficiency was an important causal factor for the attenuation of VRAC current. Intracellular loading of the STZ-diabetic myocytes with phosphatidylinositol 3,4,5-trisphosphate (PIP3), but not phosphatidylinositol 4,5-bisphosphate (PIP2), also reversed the attenuation of VRAC current. Furthermore, treatment of the normal cells with wortmannin, a phosphatidylinositol 3-kinase (PI3K) inhibitor, suppressed the development of VRAC current. We postulate that an impairment PI3K-PIP3 pathway, which may be insulin-dependent, is responsible for the attenuation of VRAC currents in STZ-diabetic myocytes.

Dead-in-bed syndrome - a diabetes nightmare

We report in this study the death in bed of a 14-yr-old girl with type 1 diabetes and a review of the existing literature on this topic. Diagnosed at 5 yr of age, the patient followed a relatively benign disease course. Hemoglobin A1c was 6.6-8.4%, and there were no hospital admissions apart from the one at diagnosis. Hypoglycemic episodes were not excessive or severe. At age 14 yr, the patient was found dead in bed after having been well the night before. No apparent explanation could be provided. The 'dead-in-bed' syndrome accounts for 5-6% of mortality cases in patients with type 1 diabetes, amounting to two to six cases per 10 000 patient years. Theories attempting to explain the mechanism for this syndrome include hypoglycemia or cardiac autonomic dysfunction. This case emphasizes several problems faced by clinicians: the risk for sudden death in youth with diabetes, which may compromise good glycemic control, the question of early detection of autonomic dysfunction, and the need to understand this phenomenon better and search for preventive measures.

Role of slow delayed rectifier K+-current in QT prolongation in the alloxan-induced diabetic rabbit heart

AIM

In diabetes mellitus, several cardiac electrophysiological parameters are known to be affected. In rodent experimental diabetes models, changes in these parameters were reported, but only limited relevant information is available in other species, having cardiac electrophysiological properties more resembling the human, including the rabbit. The present study was designed to analyse the effects of experimental type 1 diabetes on ventricular repolarization and the underlying transmembrane potassium currents in rabbit hearts.

METHODS

Diabetes was induced by a single injection of alloxan (145 mg kg(-1) i.v.). After the development of diabetes (3 weeks), electrophysiological studies were performed using whole cell voltage clamp and ECG measurements.

RESULTS

The QT(c) interval in diabetic rabbits was moderately but statistically significantly longer than measured in the control animals (155 +/- 1.8 ms vs. 145 +/- 2.8 ms, respectively, n = 9-10, P < 0.05). This QT(c)-lengthening effect of diabetes was accompanied by a significant reduction in the density of the slow delayed rectifier K(+) current, I(Ks) (from 1.48 +/- 0.35 to 0.86 +/- 0.17 pA pF(-1) at +50 mV, n = 19-21, P < 0.05) without changes in current kinetics. No differences were observed either in the density or in the kinetics of the inward rectifier K(+) current (I(K1)), the rapid delayed rectifier K(+) current (I(Kr)), the transient outward current (I(to)) and the L-type calcium current (I(CaL)) between the control and alloxan-treated rabbits.

CONCLUSION

It is concluded that type 1 diabetes mellitus, although only moderately, lengthens ventricular repolarization. Diabetes attenuates the repolarization reserve by decreasing the density of I(Ks) current, and thereby may enhance the risk of sudden cardiac death.

Intracoronary ultrasound examinations reveal significantly more advanced coronary atherosclerosis in people with type 1 diabetes than in age- and sex-matched non-diabetic controls

AIMS/HYPOTHESIS

The extent of coronary atherosclerosis is significantly more advanced in symptomatic type 1 diabetes patients than in symptomatic non-diabetic patients. Whether this difference exists between asymptomatic individuals with diabetes and controls is not documented. In vivo imaging techniques allow quantification of the difference at a preclinical stage.

METHODS

The degree of coronary atherosclerosis in early onset type 1 diabetes patients without symptoms of cardiovascular disease was compared with that of age- and sex-matched controls. Intracoronary ultrasound (IVUS) examinations were performed to determine the degree of atherosclerosis. The mean age of the patients was 43 years (35-58), they had a mean duration of disease of 30 (23-39) years and the diagnosis of type 1 diabetes was made at a mean age of 12.5 years. The controls were people with transplanted hearts; donors were sex- and age-matched and had a mean age of 43 (35-58) years.

RESULTS

The degree of subclinical coronary atherosclerosis was significantly more severe in type 1 diabetes patients than in controls. This was the case for all parameters measured. The mean plaque area was >or= 40% in 71% (54/76) of diabetic arteries as opposed to 33% (25/76) of arteries from controls (p<0.0001). The mean plaque thickness was 0.59+/-0.38 mm vs. 0.44+/-0.30 mm in controls (p<0.0001). The mean lumen area was 8.6+/-3.8 mm2 in type 1 diabetes and 12.1+/-4.3 mm2 in controls (p<0.0001).

CONCLUSIONS/INTERPRETATION

Asymptomatic individuals with type 1 diabetes have significantly more advanced subclinical coronary atherosclerosis than controls. Coronary atherosclerosis in type 1 diabetes develops at an early age.

Topical Apraclonidine Testing Discloses Pupillary Sympathetic Denervation in Diabetic Patients

BACKGROUND

Autonomic denervation is common in diabetes mellitus (DM). Pupillary sympathetic denervation (PSD) has been found in Horner syndrome following instillation of apraclonidine 0.5%. We have applied this technique to investigate the prevalence of PSD in DM.

METHODS

Apraclonidine 0.5% was instilled in the eyes of 50 patients with DM and 30 age-matched and gender-matched subjects without DM (control subjects). Pupil diameters (PD) were measured before and 60 minutes after instillation. The duration of DM and the degree of diabetic retinopathy (DR) were recorded for each patient.

RESULTS

Apraclonidine instillation caused an average of 0.9 mm of mydriasis (range 0 to 4.5 mm) in DM and -0.1 mm miosis (range 0.5 to -1 mm) in control subjects (P < 0.001). Mydriasis of at least 1 mm was observed in 42% of DM patients. The change in PD was highly correlated with the duration of DM (r = 0.368, P = 0.008) and the presence of DR (r = 0.532, P < 0.001).

CONCLUSION

Apraclonidine testing, which is easy to perform and not distressing to the patient, identified PSD in nearly half of DM patients, the degree of mydriasis being correlated to the duration of DM and the presence of DR.

Long-term mortality in a nationwide cohort of childhood-onset type 1 diabetic patients in Norway

AIMS/HYPOTHESIS

We examined long-term total and cause-specific mortality in a nationwide, population-based Norwegian cohort of patients with childhood-onset type 1 diabetes.

MATERIALS AND METHODS

All Norwegian type 1 diabetic patients who were diagnosed between 1973 and 1982 and were under 15 years of age at diagnosis were included (n=1,906). Mortality was recorded from diabetes onset until 31 December 2002 and represented 46,147 person-years. The greatest age attained among deceased subjects was 40 years and the maximum diabetes duration was 30 years. Cause of death was ascertained by reviews of death certificates, autopsy protocols and medical records. The standardised mortality ratio (SMR) was based on national background statistics.

RESULTS

During follow-up 103 individuals died. The mortality rate was 2.2/1000 person-years. The overall SMR was 4.0 (95% CI 3.2-4.8) and was similar for males and females. For ischaemic heart disease the SMR was 20.2 (7.3-39.8) for men and 20.6 (1.8-54.1) for women. Acute metabolic complications of diabetes were the most common cause of death under 30 years of age (32%). Cardiovascular disease was responsible for the largest proportion of deaths from the age of 30 years onwards (30%). Violent death accounted for 28% of the deaths in the total cohort (35% among men and 11% among women).

CONCLUSIONS/INTERPRETATION

Childhood-onset type 1 diabetes still carries an increased mortality risk when compared with the general population, particularly for cardiovascular disease. To reduce these deaths, attention should be directed to the prevention of acute metabolic complications, the identification of psychiatric vulnerability and the early detection and treatment of cardiovascular disease and associated risk factors.

Sudden cardiac death in diabetes mellitus: risk factors in the Rochester diabetic neuropathy study

OBJECTIVES

To determine risk factors for sudden cardiac death and the role of diabetic autonomic neuropathy (DAN) in the Rochester diabetic neuropathy study (RDNS).

METHODS

Associations between diabetic and cardiovascular complications, including DAN, and the risk of sudden cardiac death were studied among 462 diabetic patients (151 type 1) enrolled in the RDNS. Medical records, death certificates, and necropsy reports were assessed for causes of sudden cardiac death.

RESULTS

21 cases of sudden cardiac death were identified over 15 years of follow up. In bivariate analysis of risk covariates, the following were significant: ECG 1 (evolving and previous myocardial infarctions): hazard ratio (HR) = 4.4 (95% confidence interval (CI), 1.6 to 12.1), p = 0.004; ECG 2 (bundle branch block or pacing): HR = 8.6 (2.9 to 25.4), p<0.001; ECG 1 or ECG 2: HR = 4.2 (1.3 to 13.4), p = 0.014; and nephropathy stage: HR = 2.1 (1.3 to 3.4), p = 0.002. Adjusting for ECG 1 or ECG 2, autonomic scores, QTc interval, high density lipoprotein (HDL) cholesterol, 24 hour microalbuminuria, and 24 hour total proteinuria were significant. However, adjusting for nephropathy, none of the autonomic indices, QTc interval, HDL cholesterol, microalbuminuria, or total proteinuria was significant. At necropsy, all patients with sudden cardiac death had coronary artery or myocardial disease.

CONCLUSIONS

Sudden cardiac death was correlated with atherosclerotic heart disease and nephropathy, and to a lesser degree with DAN and HDL cholesterol. Although DAN is associated with sudden cardiac death, it is unlikely to be its primary cause.

Morphologic Findings of Coronary Atherosclerotic Plaques in Diabetics

OBJECTIVE

Coronary atherosclerotic plaque composition of diabetic subjects and localization of receptor for advanced glycation end products (RAGE) and its ligands have not been extensively studied.

METHODS AND RESULTS

Hearts from diabetic subjects and age, race, and sex-matched nondiabetic subjects dying suddenly were examined. Coronary arteries were dissected and lesions were evaluated for plaque burden, necrotic core size, and inflammatory infiltrate. The expression of RAGE, the RAGE-binding protein (S100-A12, EN-RAGE), and cell death (apoptosis) were also determined. Lesions from type II diabetic subjects had larger mean necrotic cores (P=0.01) and greater total and distal plaque load (P<0.001) than nondiabetic subjects. Necrotic core size correlated positively with diabetic status, independent of other risk factors. Intimal staining for macrophages, T-cells, and HLA-DR was also significantly greater in diabetic subjects (P=0.03, P=0.003, and P<0.0001), respectively. The association of increased macrophage infiltrate was independent of cholesterol levels and patient age. Expression of RAGE and EN-RAGE was significantly greater in diabetic subjects (P=0.004) and was associated with apoptotic smooth muscle cells and macrophages.

CONCLUSIONS

In sudden coronary death, inflammation and necrotic core size play a greater role in the progression of atherosclerosis in diabetic subjects. The expression of RAGE and EN-RAGE may further compromise cell survival and promote plaque destabilization.

Disruption of intestinal motility by a calcium channel-stimulating autoantibody in type 1 diabetes

BACKGROUND & AIMS

Autonomic neuropathy, including gastrointestinal dysfunction, is a common complication of type 1 diabetes; however, its cause is uncertain. This study aimed to test whether functional autoantibodies cause the gastrointestinal dysfunction.

METHODS

We used isolated mouse colon undergoing colonic migrating motor complex (MMC) activity to test for autoantibodies that disrupt colonic motility. Purified immunoglobulin G (IgG) from patients with type 1 diabetes or from controls was tested either in vitro or after passive transfer. Pharmacological studies of the interaction between the IgG and L-type calcium channel activator (Bay K8644) and inhibitors (nicardipine and verapamil) were performed. The effect of IgG on nerve-evoked contraction of the vas deferens longitudinal smooth muscle was also assessed.

RESULTS

MMC activity was disrupted by IgG (0.2 mg/mL) from 8 of 16 patients with type 1 diabetes but not by control IgG. Passive transfer of diabetic IgG to mice also disrupted MMCs, showing access to the antigen in vivo. The acute effect of the autoantibody was mimicked by the dihydropyridine agonist, Bay K8644 (2-10 nmol/L), and both Bay K8644 and the autoantibody competitively inhibited the effect on MMC contraction of the dihydropyridine antagonist, nicardipine. Diabetic IgG, but not control IgG, altered the nerve-evoked contractile activity of vas deferens smooth muscle effects mimicked by Bay K8644.

CONCLUSIONS

A novel functional autoantibody that activates smooth muscle L-type calcium channels at the dihydropyridine binding site is produced specifically by patients with type 1 diabetes and may mediate gastrointestinal and autonomic dysfunction in these patients.

Pupil signs of sympathetic autonomic neuropathy in patients with type 1 diabetes

OBJECTIVE

Pupillary autonomic neuropathy is considered an early sign of the development of systemic autonomic neuropathy. Sympathetic denervation is related to the duration of diabetes and the development of systemic autonomic dysfunction. We investigated pupil responsiveness to directly and indirectly acting sympathomimetics in type 1 diabetic patients with and without long-term complications, defined as cardiac autonomic neuropathy (CAN), peripheral sensomotor neuropathy, retinopathy, and nephropathy, and in healthy subjects.

RESEARCH DESIGN AND METHODS

A total of 47 randomly chosen type 1 diabetic patients and 20 healthy subjects were selected for this study. Patients were divided into groups determined by whether they had long-term diabetic complications. Pharmacological tests were performed with cocaine 4%, epinephrine 1%, and pholedrine 5% eye drops. Horizontal pupil diameter (HPD) was measured at the beginning of the pharmacological tests and at defined time points after instillation of the eye drops.

RESULTS

Statistical analysis showed a significantly smaller HPD in the patients before instillating eye drops (P = 0.011). In particular, the HPD was significantly smaller in the patient group without CAN when compared with healthy subjects (P = 0.004). Maximal cocaine reaction was diminished in the complication group (P < 0.001). Epinephrine test, visual acuity, ocular pressure, and HbA(1c) did not differ in patients with or without long-term complications. The noncomplication group showed no significant differences in pupillary responses as compared with healthy subjects. The complication group showed a smaller HPD (P = 0.022), reduced pupillary responses in the cocaine (P = 0.037) and pholedrine tests (P < 0.001), and anisocor pupil sizes after instillation of the eye drops (P = 0.034).

CONCLUSIONS

Our results clearly show that sympathetic denervation does exist in the pupil of diabetic patients and that it can be rapidly assessed using the cocaine test. These data and the results of the epinephrine test suggest a mixed pre- and postganglionic dysfunction of the sympathetic plexus. The significant smaller HPD in patients without CAN compared with that of healthy subjects could be a sign for early involvement of the pupil function before cardiac manifestation of systemic autonomic diabetic neuropathy.