Sudden death in young patients with Type 1 diabetes: a consequence of disease, treatment or both?

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.

Recent Updates on Type 1 Diabetes Mellitus Management for Clinicians

Type 1 diabetes mellitus (T1DM) is a chronic autoimmune condition that requires life-long administration of insulin. Optimal management of T1DM entails a good knowledge and understanding of this condition both by the physician and the patient. Recent introduction of novel insulin preparations, technological advances in insulin delivery and glucose monitoring, such as continuous subcutaneous insulin infusion (CSII) and continuous glucose monitoring and improved understanding of the detrimental effects of hypoglycaemia and hyperglycaemia offer new opportunities and perspectives in T1DM management. Evidence from clinical trials suggests an important role of structured patient education. Our efforts should be aimed at improved metabolic control with concomitant reduction of hypoglycaemia. Despite recent advances, these goals are not easy to achieve and can put significant pressure on people with T1DM. The approach of physicians should therefore be maximally supportive. In this review, we provide an overview of the recent advances in T1DM management focusing on novel insulin preparations, ways of insulin administration and glucose monitoring and the role of metformin or sodium-glucose co-transporter 2 inhibitors in T1DM management. We then discuss our current understanding of the effects of hypoglycaemia on human body and strategies aimed at mitigating the risks associated with hypoglycaemia.

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.

Managing hypoglycaemia

Intensive glycaemic control reduces the diabetic microvascular disease burden but iatrogenic hypoglycaemia is a major barrier preventing tight glycaemic control because of the limitations of subcutaneous insulin preparations and insulin secretagogues. Severe hypoglycaemia is uncommon early in the disease as robust physiological defences, particularly glucagon and adrenaline release, limit falls in blood glucose whilst associated autonomic symptoms drive patients to take action by ingesting oral carbohydrate. With increasing diabetes duration, glucagon release is progressively impaired and sympatho-adrenal responses are activated at lower glucose levels. Repeated hypoglycaemic episodes contribute to impaired defences, increasing the risk of severe hypoglycaemia in a vicious downward spiral. Managing hypoglycaemia requires a systematic clinical approach with structured insulin self-management training and support of experienced diabetes educators. Judicious use of technologies includes insulin analogues, insulin pump therapy, continuous glucose monitoring, and in a few cases islet cell transplantation. Some individuals require specialist psychological support.

Dynamic estimation of cardiac repolarization characteristics during hypoglycemia in healthy and diabetic subjects

Hypoglycemia is known to affect the repolarization characteristics of the heart, but the mechanisms behind these changes are not completely understood. We analyzed repolarization characteristics continuously from 22 subjects during normoglycemic period, transition period (blood glucose concentration decreasing) and hypoglycemic period from nine healthy controls (Healthy), six otherwise healthy type 1 diabetics (T1DM) and seven type 1 diabetics with disease complications (T1DMc). An advanced principal component regression (PCR)-based method was used for estimating ECG parameters beat-by-beat, and thus, continuous comparison between the repolarization characteristics and blood glucose values was made. We observed that hypoglycemia related ECG changes in the T1DMc group were smaller than changes in the Healthy and T1DM groups. We also noticed that when glucose concentration remained at a low level, the heart rate corrected QT interval prolonged progressively. Finally, a few minutes time lag was observed between the start of hypoglycemia and cardiac repolarization changes. One explanation for these observations could be that hypoglycemia related hormonal changes have a significant role behind the repolarization changes. This could explain at least the observed time lag (hormonal changes are slow) and the lower repolarization changes in the T1DMc group (hormonal secretion lowered in long duration diabetics).

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.

Effects of a controlled hypoglycaemia test on QTc in adolescents with Type 1 diabetes

Our objective was to test the ventricular repolarization response to a controlled hypoglycaemia test in Type 1 diabetic adolescents, an age group at risk for 'dead in bed syndrome'. We measured QTc, blood glucose level, potassium, heart rate, blood pressure and urinary metanephrine levels in 16 Type 1 diabetic adolescents during an insulin clamp mimicking the transition from mild hyperglycaemia to hypoglycaemia. QTc increased in all patients by 146 +/- 44 ms (mean +/-sd) ranging from 70 to 230 ms. The longest QTc (630 ms) was recorded in the sibling of a diabetic patient found 'dead in bed'. Heart rate and urinary metanephrine levels correlated with QTc (r = 0.60 and 0.79, respectively; P = 0.02 and 0.003). QTc in euglycaemia showed no correlation with hypoglycaemia associated QTc prolongation. The prognostic value of the hypoglycaemia test for the risk of recurrent episodes of QTc prolongation should be evaluated in real-life conditions in large-scale studies of diabetic adolescents.

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.

Effect of atenolol on QTc interval lengthening during hypoglycaemia in type 1 diabetes

AIMS/HYPOTHESIS

Hypoglycaemia is associated with heart rate-corrected QT (QTc) interval lengthening on the ECG; this may be important in the pathogenesis of sudden overnight death in young people with diabetes. Since hypoglycaemic QTc lengthening appears to be mediated through the sympathoadrenal response, we tested the hypothesis that beta1-blockade will prevent these changes in type 1 diabetic patients and so provide a potential therapeutic intervention.

METHODS

We studied eight type 1 diabetic adults without cardiovascular or renal complications. Similar hypoglycaemic clamp studies were performed on two occasions, at least 4 weeks apart, but immediately before one visit subjects received atenolol 100 mg daily for 7 days. Following a 60-min euglycaemic (5 mmol/l) period, blood glucose was lowered over 30 min to 2.5 mmol/l, and held for 60 min. High-resolution ECG was recorded at baseline and at 0, 30 and 60 min during each glycaemic plateau. QT interval was measured using a semiautomated tangent method and QTc was derived from QT using the Fridericia formula.

RESULTS

Mean (SD) baseline QTc was similar at both visits: control 391 (30) ms, post-atenolol 386 (34) ms; (p=0.33). Without atenolol pretreatment, QTc lengthened during hypoglycaemia to a maximum of 448 (34) ms (p<0.001). On atenolol, QTc lengthening was significantly reduced (peak QTc 413 (27) ms; p=0.004 vs control visit).

CONCLUSIONS/INTERPRETATION

Hypoglycaemic QTc lengthening is blunted by atenolol in patients with type 1 diabetes. Selective beta1-blockade may help prevent sudden death, if we can identify those at high risk.

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.

Prolonged cardiac repolarisation during spontaneous nocturnal hypoglycaemia in children and adolescents with type 1 diabetes

AIMS/HYPOTHESIS

It has been postulated that hypoglycaemia-related cardiac dysrhythmia and, in particular, prolonged cardiac repolarisation, may contribute to increased mortality rates in children and adolescents with type 1 diabetes.

METHODS

We examined the prevalence of prolonged QT interval on ECG during spontaneous hypoglycaemia in 44 type 1 diabetic subjects (aged 7-18 years), and explored the relationships between serial overnight measurements of QT interval corrected for heart rate (QTc) and serum glucose, potassium and epinephrine levels. Each subject underwent two overnight profiles; blood was sampled every 15 min for glucose measurements and hourly for potassium and epinephrine. Serial ECGs recorded half-hourly between 23.00 and 07.00 hours were available on 74 nights: 29 with spontaneous hypoglycaemia (defined as blood glucose <3.5 mmol/l) and 45 without hypoglycaemia.

RESULTS

Mean overnight QTc was longer in females than in males (412 vs 400 ms, p=0.02), but was not related to age, diabetes duration or HbA(1)c. Prolonged QTc (>440 ms) occurred on 20 out of 74 (27%) nights, with no significant differences between male and female subjects, and was more prevalent on nights with hypoglycaemia (13/29, 44%) than on nights without (7/45, 15%, p=0.0008). Potassium levels were lower on nights when hypoglycaemia occurred (minimum potassium 3.4 vs 3.7 mmol/l, p=0.0003) and were inversely correlated with maximum QTc (r=-0.40, p=0.03). In contrast, epinephrine levels were not higher on nights with hypoglycaemia and were not related to QTc.

CONCLUSIONS/INTERPRETATION

In young type 1 diabetic subjects, prolonged QTc occurred frequently with spontaneous overnight hypoglycaemia and may be related to insulin-induced hypokalaemia.

Influence of autonomic neuropathy on QTc interval lengthening during hypoglycemia in type 1 diabetes

Hypoglycemia produces electrocardiographic QTc lengthening, a predictor of arrhythmia risk and sudden death. This results from both sympatho-adrenal activation and a lowered serum potassium. It has been suggested that cardiac autonomic neuropathy (CAN) might indicate those who are at particular risk. We tested this hypothesis in 28 adults with type 1 diabetes and 8 nondiabetic control subjects. After standard tests of autonomic function and baroreflex sensitivity (BRS) measurement, diabetic participants were divided into three groups: 1) CAN- with normal BRS (BRS+; n = 10), 2) CAN- with impaired BRS (BRS-; n = 9), and 3) CAN+ (n = 9). QTc was then measured during controlled hypoglycemia (2.5 mmol/l) using a hyperinsulinemic clamp. Mean (+/-SE) QTc lengthened from 377 +/- 9 ms (baseline) to a maximum during hypoglycemia of 439 +/- 13 ms in BRS+ subjects and from 378 +/- 5 to 439 +/- 10 ms in control subjects. Peak QTc tended to be lower in CAN+ (baseline, 383 +/- 6; maximum, 408 +/- 10) and BRS- groups (baseline, 380 +/- 8; maximum, 421 +/- 11; F = 1.7, P = 0.18). Peak epinephrine concentrations (nmol/l) were 3.1 +/- 0.8 (BRS+), 2.6 +/- 0.5 (BRS-), 1.4 +/- 0.3 (CAN+), and 5.7 +/- 0.8 (control subjects). These data do not indicate that those with CAN are at particular risk for abnormal cardiac repolarization during hypoglycemia. Indeed, they suggest that such patients may be relatively protected, perhaps as a result of attenuated sympatho-adrenal responses.

Changes in cardiac repolarization during clinical episodes of nocturnal hypoglycaemia in adults with Type 1 diabetes

AIMS/HYPOTHESIS

Experimental hypoglycaemia leads to abnormal cardiac repolarization manifest by a lengthened QT interval and caused by adrenergic stimulation. However it is less clear whether spontaneous clinical episodes lead to similar changes. We have therefore measured cardiac ventricular repolarization and counterregulatory responses in patients with Type 1 diabetes during hypoglycaemic and euglycaemic nights.

METHODS

We studied 22 patients with Type 1 diabetes (mean age 40.4+/-17.2 years, duration of diabetes 17.2+/-9.3 years, HbA1c 8.2+/-1.2% overnight). Measurements were taken hourly of blood glucose, plasma potassium, catecholamines and high resolution electrocardiograms.

RESULTS

Hypoglycaemia (blood glucose level <2.5 mmol/l) occurred on 7 of the 22 nights. During overnight hypoglycaemia, QTc interval increased by 27 ms (+/-15) above baseline, compared with 9 ms (+/-19) during nights with no nocturnal hypoglycaemia (p=0.034, 95%CI 2, 35). Adrenaline increased by 0.33 nmol/l (+/-0.21) above baseline during hypoglycaemia, compared with -0.05 nmol/l (+/-0.08) during euglycaemia (p=0.001, 95%CI 0.19, 0.56 nmol/l). There was no significant difference between potassium, and noradrenaline concentrations between the two groups.

CONCLUSION/INTERPRETATION

QTc interval lengthens significantly during spontaneous nocturnal hypoglycaemia. Increases are generally less than those observed during experimental hypoglycaemia and could reflect attenuated sympathoadrenal responses during clinical episodes. The clinical relevance of these changes is uncertain but is consistent with the hypothesis that clinical hypoglycaemia can cause abnormal cardiac repolarization and an attendant risk of cardiac arrhythmia.

Mechanisms of abnormal cardiac repolarization during insulin-induced hypoglycemia

Prolonged cardiac repolarization causes fatal cardiac arrhythmias. There is evidence that these contribute to sudden death associated with nocturnal hypoglycemia in young people with diabetes. We measured cardiac repolarization (QT interval [QTc] and QT dispersion [QTd]) during experimental hypoglycemia with and without beta-blockade and potassium infusion to establish possible mechanisms. Two groups of 10 nondiabetic men (study 1 and study 2) each underwent four hyperinsulinemic clamps: two euglycemic (5 mmol/l) and two hypoglycemic (5 mmol/l and 2.5 mmol/l for 60 min each). Study 1 was performed with and without potassium infusion to maintain normal concentrations and study 2 with and without beta-blockade (atenolol, 100 mg/day for 7 days). QTd was unchanged during euglycemia but increased during hypoglycemia (55 ms, P < 0.0001 vs. baseline), which was prevented by potassium (6 ms, P = 0.78). QTc increased significantly during hypoglycemia alone (67 ms, P < 0.0001) and during potassium replacement (46 ms, P = 0.02). In study 2, the increase in QTd during hypoglycemia (68 ms, P < 0.0001) was prevented by beta-blockade (3 ms, P = 0.88). The increase in QTc during hypoglycemia (55 ms, P < 0.0001) was prevented by beta-blockade (1 ms, P = 0.98). Our data indicate that hypoglycemia causes an acquired long QT syndrome. Sympathoadrenal stimulation is the main cause, through mechanisms that involve but are not limited to catecholamine-mediated hypokalemia. These abnormalities are prevented by selective beta-blockade.

Comparative effect of human soluble insulin and insulin aspart upon hypoglycaemia-induced alterations in cardiac repolarization

AIMS

Sudden death in young diabetic patients has been associated with nocturnal hypoglycaemia perhaps as a result of cardiac dysrhythmias following abnormal cardiac repolarization during hypoglycaemia. It was therefore important to compare the effect of soluble human insulin (HI) and a rapid-acting insulin analogue, insulin aspart (IAsp), on these aspects of cardiac function.

METHODS

A total of 17 healthy males underwent identical hyperinsulinaemic hypoglycaemic clamps with blood glucose maintained at 5 mm for 30 min and reduced to 2.5 mm after an additional 30 min. Subjects received either HI or IAsp on two different occasions separated by 4-6 weeks. Regular measurements were made of two measures of cardiac repolarization, QT dispersion and QTc as well as of counter-regulatory hormones.

RESULTS

The blood glucose lowering effect did not differ between IAsp and HI and the clearance rates were similar (HI mean +/- SD 1.24 +/- 0.12 l h(-1) kg(-1), IAsp mean +/- s.d. 1.22 +/- 0.32 l h(-1) kg(-1)). There were similar significant increases but no difference between treatments in QTc after hypoglycaemia induced by either IAsp or HI (480 +/- 37 ms vs 480 +/- 25 ms; NS). However, QT dispersion during hypoglycaemia was less pronounced with IAsp than with HI (92 +/- 36 ms vs 107 +/- 42 ms; P < 0.05). Plasma adrenaline increased significantly and similarly after both insulins (initial and final concentration, HI, 0.23 +/- 0.01 to 4.87 +/- 0.48 nm, P < 0.001, IAsp, 0.24 +/- 0.01 to 4.99 +/- 0.48 nm, P < 0.001). Serum potassium decreased significantly but by a similar amount between the groups (initial and final concentration, HI, 4.18 +/- 0.3 to 4.2 +/- 0.2 mm, P < 0.001, IAsp, 4.2 +/- 0.3 to 4.2 +/- 0.3 mm, P < 0.001).

CONCLUSIONS

Soluble human insulin and insulin aspart had similar effects upon hypoglycaemia-induced alterations in cardiac repolarization, presumably because the effects of both regular insulin and insulin aspart on the sympathoadrenal response and potassium concentration were the same.

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.

Should cisapride be avoided in patients with diabetic gastroparesis?

The gastrointestinal motility stimulants, cisapride and erythromycin, have been used in the management of diabetic gastroparesis. However, drug interactions may result in prolongation of the electrocardiographic QT interval with the risk of ventricular arrhythmias. These drugs should, therefore, not be used in combination. We report two cases that illustrate inappropriate use of these agents. Moreover, patients with recurrent severe hypoglycemia or renal impairment may be at increased risk from cisapride-related cardiotoxicity. Thus, even as monotherapy, cisapride may pose dangers for high-risk diabetic patients.