Growth hormone secretion, fatigue and quality of life after childhood traumatic brain injury.

CONTEXT: Traumatic brain injury (TBI) is a recognised cause of hypopituitarism in adults but the prevalence after childhood TBI remains controversial. OBJECTIVE: To investigate long-term endocrine outcomes and quality of life (PedsQL and QoL-AGHDA (Quality of Life in Adult Growth Hormone Deficiency Assessment)) following childhood TBI. DESIGN: Prospective study. METHODS: Participants with moderate/severe TBI (n = 31) and controls (n = 17). Mean (range) age: 19.8 ± 4.2 (11-26), time post TBI: 9 (7-11) years. Detailed endocrine evaluation of stimulated (insulin tolerance test (ITT)) and spontaneous GH secretion (overnight profile) was undertaken in the TBI group; QoL and neuroimaging in both groups. RESULTS: No participant had seizures, short stature, precocious puberty or hypothyroidism. In 6/25 the ITT GH response was below age-defined cut-offs and cortisol <500 nmol/L in 2/25. Mean spontaneous GH secretion was <3.1 µg/L in 16/22 but peak GH was low only in 1/22 profiles. One patient had abnormal spontaneous and stimulated GH secretion and hypogonadism. Fatigue and depression scores were higher in TBI patients (P = .011 and P = .020). Fatigue correlated with measures of spontaneous but not stimulated GH secretion. Overall QoL (PedsQL) did not differ between groups but specific attributes of health state (cognition, memory) were impaired in TBI patients. Pituitary neuroimaging was normal in all participants. CONCLUSIONS: Fatigue and depression were common 8-10 years post childhood TBI. One individual had GHD (1/22) using rigorous diagnostic criteria. A single ITT potentially over-diagnosed GHD in 25% (6/25) without clear correlation with symptoms underlying the importance of using two diagnostic tests in TBI survivors.

Molecular spectrum of TSHß subunit gene defects in central hypothyroidism in the UK and Ireland.

OBJECTIVE: Homozygous mutations in the TSH beta subunit gene (TSHB) result in severe, isolated, central congenital hypothyroidism (CCH). This entity evades diagnosis in TSH-based congenital hypothyroidism (CH) screening programmes in the UK and Ireland. Accordingly, genetic diagnosis, enabling ascertainment of affected relatives in families, is critical for prompt diagnosis and treatment of the disorder. DESIGN, PATIENTS AND MEASUREMENTS: Four cases of isolated TSH deficiency from three unrelated families in the UK and Ireland were investigated for mutations or deletions in TSHB. Haplotype analysis, to investigate a founder effect, was undertaken in cases with identical mutations (c.373delT). RESULTS: Two siblings in kindred 1 were homozygous for a previously described TSHB mutation (c.373delT). In kindreds 2 and 3, the affected individuals were compound heterozygous for TSHB c.373delT and either a 5·4-kB TSHB deletion (kindred 2, c.1-4389_417*195delinsCTCA) or a novel TSHB missense mutation (kindred 3, c.2T>C, p.Met1?). Neurodevelopmental retardation, following delayed diagnosis and treatment, was present in 3 cases. In contrast, the younger sibling in kindred 1 developed normally following genetic diagnosis and treatment from birth. CONCLUSIONS: This study, including the identification of a second, novel, TSHB deletion, expands the molecular spectrum of TSHB defects and suggests that allele loss may be a commoner basis for TSH deficiency than previously suspected. Delayed diagnosis and treatment of profound central hypothyroidism in such cases result in neurodevelopmental retardation. Inclusion of thyroxine (T4) plus thyroxine-binding globulin (TBG), or free thyroxine (FT4) in CH screening, together with genetic case ascertainment enabling earlier therapeutic intervention, could prevent such adverse sequelae.

Survivors of childhood leukaemia treated with haematopoietic stem cell transplantation and total body irradiation should undergo screening for diabetes by oral glucose tolerance tests.

AIMS: Childhood cancer survivors treated with haematopoietic stem cell transplantation (HSCT) and total body irradiation are at an increased risk of developing diabetes early in life due to insulin resistance and ß-cell dysfunction, but the optimal screening method is unknown. The National Institute for Health and Care Excellence guidelines for community diabetes screening recommend using fasting glucose ≥ 7 mmol/l and/or HbA1c ≥ 48 mmol/mol (6.5%) for diagnosis and, fasting glucose 5.5-6.9 mmol/l or HbA1c 42-47 mmol/mol (6-6.5%) to indicate high risk. This study aimed to evaluate the sensitivities of fasting glucose and HbA1c in the diagnosis of diabetes and impaired glucose tolerance in childhood HSCT survivors. METHOD: The patients were 35 (male = 19) HSCT survivors from a single UK centre under follow-up from 2006 to 2013. Patients had a median age (range) of 19.2 (13.1-26.2) years and had been treated for acute lymphoblastic (n = 31) or myeloid (n = 4) leukaemia when aged 7.8 (2.4-16.7) years. The outcome measures were oral glucose tolerance test (OGTT), fasting glucose and HbA1c . RESULTS: OGTT identified 6 patients with diabetes (120-min glucose ≥ 11.1 mmol/l), 12 with impaired glucose tolerance (120-min glucose 7.8-11.0 mmol/l) and 2 with impaired fasting glucose (≥ 7 mmol/l). Fasting glucose ≥ 7 mmol/l or HbA1c ≥ 48 mmol/mol identified two of the six patients with diabetes diagnosed on OGTT. Fasting glucose ≥ 5.5 mmol/l and HbA1c ≥ 42 mmol/mol identified three and two patients, respectively, with diabetes. Only 1 of 12 patients with impaired glucose tolerance had a fasting glucose ≥ 5.5 mmol/l and none had HbA1c ≥ 42 mmol/mol (≥ 6%). CONCLUSIONS: The fasting glucose and HbA1c cut-offs used in UK population screening only identified one-third of HSCT survivors with diabetes and do not identify those at risk. Diabetes screening in HSCT survivors requires standard OGTTs.

Growth hormone deficiency after childhood bone marrow transplantation with total body irradiation: interaction with adiposity and age.

OBJECTIVE: Bone marrow transplantation with total body irradiation (BMT/TBI) has adverse effects on growth, growth hormone status and adiposity. We investigated the GH-IGF-I axis in relation to adiposity. DESIGN: Cross-sectional case control study. PATIENTS: BMT/TBI survivors (n = 22) and short stature control participants (n = 19), all GH-naïve or off GH treatment >3 months. MEASUREMENTS: Auxology, DEXA scans and GH-IGF-I axis investigation: (i) 12-h overnight GH profiles; (ii) insulin tolerance test (ITT); and (iii) IGF-I generation test. ANALYSIS: auto-deconvolution of GH profile data and comparison of quantitative parameters using ANOVA. RESULTS: Eighty-two percent of BMT/TBI survivors had growth hormone deficiency (GHD) using ITT. GH profile area-under-the-curve (GH-AUC) was reduced in BMT/TBI survivors vs short stature control participants [geometric mean (range) 209 (21-825) vs 428 (64-1400) mcg/l/12 h, respectively, P = 0·007]. GHD was more marked in those who had additional cranial irradiation (CRT) [ITT peak 1·4 (0·2-3·0) vs TBI only 4·1 (1·1-14·8) mcg/l, P = 0·036]. GHD was more marked at the end of growth in BMT/TBI survivors vs short stature control participants (GH-AUC 551 (64-2474) vs 1369 (192-4197) mcg/l/12 h, respectively, P = 0·011) and more prevalent (9/11 vs 1/9, respectively, P = 0·005). GH profile data were consistent with ITT results in 80% of participants. IGF-I generation tests were normal. BMT/TBI survivors still demonstrated lower GH levels after adjustment for adiposity (fat-adjusted mean difference for GH-AUC 90·9 mcg/l/12 h, P = 0·025). CONCLUSIONS: GHD was more prevalent in BMT/TBI survivors than expected for the CRT dose in TBI, worsened with time and persisted into adulthood. GHD could not be explained by adiposity. There was no evidence of GH neurosecretory dysfunction or resistance after BMT/TBI.

Development and evaluation by a cluster randomised trial of a psychosocial intervention in children and teenagers experiencing diabetes: the DEPICTED study.

OBJECTIVE: To develop and evaluate a health-care communication training programme to help diabetes health-care professionals (HCPs) counsel their patients more skilfully, particularly in relation to behaviour change. DESIGN: The HCP training was assessed using a pragmatic, cluster randomised controlled trial. The primary and secondary analyses were intention-to-treat comparisons of outcomes using multilevel modelling to allow for cluster (service) and individual effects, and involved two-level linear models. SETTING: Twenty-six UK paediatric diabetes services. PARTICIPANTS: The training was delivered to HCPs (doctors, nurses, dietitians and psychologists) working in paediatric diabetes services and the effectiveness of this training was measured in 693 children aged 4-15 years and families after 1 year (95.3% follow-up). INTERVENTIONS: A blended learning programme was informed by a systematic review of the literature, telephone and questionnaire surveys of professional practice, focus groups with children and parents, experimental consultations and three developmental workshops involving a stakeholder group. The programme focused on agenda-setting, flexible styles of communication (particularly guiding) and a menu of strategies using web-based training and practical workshops. MAIN OUTCOME MEASURES: The primary trial outcome was a change in glycosylated haemoglobin (HbA1c) levels between the start and finish of a 12-month study period. Secondary trial outcomes included change in quality of life, other clinical [including body mass index (BMI)] and psychosocial measures (assessed at participant level as listed above) and cost (assessed at service level). In addition, patient details (HbA1c levels, height, weight, BMI, insulin regimen), health service contacts and patient-borne costs were recorded at each clinic visit, along with details of who patients consulted with, for how long, and whether or not patients consulted on their own at each visit. Patients and carers were also asked to complete an interim questionnaire assessing patient enablement (or feelings towards clinic visit for younger patients aged 7-10 years) at their first clinic visit following the start of the trial. The cost of the intervention included the cost of training intervention teams. RESULTS: Trained staff showed better skills than control subjects in agenda-setting and consultation strategies, which waned from 4 to 12 months. There was no effect on HbA1c levels (p = 0.5). Patients in intervention clinics experienced a loss of confidence in their ability to manage diabetes, whereas controls showed surprisingly reduced barriers (p = 0.03) and improved adherence (p = 0.05). Patients in intervention clinics reported short-term increased ability (p = 0.04) to cope with diabetes. Parents in the intervention arm experienced greater excitement (p = 0.03) about clinic visits and improved continuity of care (p = 0.01) without the adverse effects seen in their offspring. The mean cost of training was £13,145 per site or £2163 per trainee. There was no significant difference in total NHS costs (including training) between groups (p = 0.1). CONCLUSIONS: Diabetes HCPs can be trained to improve consultation skills, but these skills need reinforcing. Over 1 year, no benefits were seen in children, unlike parents, who may be better placed to support their offspring. Further modification of this training is required to improve outcomes that may need to be measured over a longer time to see effects. TRIAL REGISTRATION: Current Controlled Trials ISRCTN61568050. FUNDING: This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 15, No. 29. See the HTA programme website for further project information.

Communication skills of healthcare professionals in paediatric diabetes services.

AIMS: To identify training needs in communication skills and to assess training preferences of staff working in paediatric diabetes services, which will inform the development of a learning programme in behaviour change counselling for healthcare professionals. METHODS: Three hundred and eighty-five staff in 67 UK paediatric diabetes services were sent questionnaires to determine their previous communication skills training, to measure their self-reported view of the importance of and confidence in addressing common clinical problems and to assess the perceived feasibility of training methods to improve skillfulness. RESULTS: Two hundred and sixty-six questionnaires (69%) were returned from 65 services. Sixteen per cent of doctors, nurses and dietitians reported no previous training in communication skills and 47% had received no training since graduating. Respondents rated psychosocial issues as more important to address than medical issues within consultations (t = 8.93, P < 0.001), but felt less confident addressing such issues (t = 15.85, P < 0.001). One-day workshops and monthly team meetings were the most popular of the training options considered (65% and 77%, respectively). CD ROM and web-based learning were considered feasible for 54% and 56% of respondents, respectively, although lack of time (55%) and privacy (34%) were potential barriers. CONCLUSIONS: Addressing psychosocial issues is an important component of consultations involving young people with diabetes, but healthcare professionals find it easier to address medical issues. This represents a key training need in communication skills for diabetes professionals. The survey will inform the development of a tailored learning programme for health professionals in UK paediatric diabetes clinics.

Elevated glucose concentrations during an oral glucose tolerance test are associated with the presence of metabolic syndrome in childhood obesity.

AIMS: To investigate whether changes in glucose concentrations during an OGTT in obese children reflect the presence of peripheral insulin resistance and/or cardiovascular risk factors more closely than single measurements of fasting plasma glucose (FPG). METHODS: One hundred and twenty-two obese children attending our Paediatric Obesity Service underwent formal OGTTs, following the measurement of blood pressure and fasting levels of insulin, glucose and lipid profiles in the majority. Fasting insulin was used as a surrogate measure of insulin sensitivity. Three different child-specific definitions for metabolic syndrome were used to identify clustering of cardiovascular risk factors in 65 of these children. RESULTS: In the whole group, 10.7% had IGT but changes in glucose during the OGTT were not influenced by age, sex, pubertal status or raw (or age- and sex-adjusted) body mass index (BMI). During the OGTT, FPG, glucose at 60 min and area under the glucose curve correlated highly with fasting insulin. Children with metabolic syndrome (defined using any of three definitions) had comparable FPG levels to those without metabolic syndrome, but they demonstrated significantly elevated glucose levels at 60 min. On sub-group analysis, obese children with normal carbohydrate metabolism were significantly more likely to have a 1 h glucose level > or = 7.8 mmol/l if they had metabolic syndrome (P = 0.026). CONCLUSIONS: These data suggest that an elevated 1 h post-load glucose measurement is seen in obese children who have a coexistent clustering of cardiovascular risk factors.

Characterisation of morbidity in a UK, hospital based, obesity clinic.

AIM: To identify clinical features which predict those most at risk of co-morbidities within an obesity clinic. METHODS: Children attending an obesity clinic had fasting glucose, insulin, and lipids measured prior to a standard oral glucose tolerance test (OGTT). History and examination established birth weight, family history of type 2 diabetes/obesity, pubertal status, and presence of acanthosis nigricans. Central and total fat mass was estimated by bio-impedance. RESULTS: Of the 126 children evaluated, 10.3% (n = 13) had impaired glucose tolerance (IGT); the majority (n = 11) of these would not have been identified on fasting glucose alone. Those with IGT were more likely to have a parental history of type 2 diabetes (relative risk 3.5). IGT was not associated with acanthosis nigricans. Twenty five per cent (n = 19) of those evaluated (n = 75) had evidence of the "metabolic syndrome" (MS). HDL cholesterol and triglyceride levels were related to insulin sensitivity (HOMA-R); HDL cholesterol was also related to birth weight SDS. We observed a trend for those with MS to have a lower birth weight SDS. The severity of obesity did not influence the likelihood of IGT or MS. CONCLUSIONS: Significant numbers of obese children have associated co-morbidities. Analysis of fasting blood glucose samples alone is not satisfactory to adequately evaluate glucose homoeostasis. The overall level of obesity does not predict co-morbidities. Special attention should be given to those with parental diabetes and a history of low birth weight who are more likely to have IGT and abnormal lipid profiles respectively.

Physical activity patterns in nonobese and obese children assessed using minute-by-minute accelerometry.

OBJECTIVE: To determine the levels and patterns of physical activity in a sample of obese (> or =99th percentile body mass index (BMI)) and nonobese (<99th percentile BMI) children. DESIGN: Cross-sectional study. SETTING: Children were recruited from schools in Bristol and from the childhood obesity clinic, Bristol Royal Hospital for Children. Children were instructed in the use of the accelerometer either while at school or in the clinic, and wore the instrument while carrying out their normal daily activities for 7 days. PARTICIPANTS: A total of 133 children (mean age 10.5+/-0.8 y). In all 11 (16.9%) of the 65 girls and 14 (20.6%) of the 68 boys were classified as obese (above the 99th percentile for BMI and corresponding to projected adult BMI of 30). MAIN OUTCOME MEASURES: Objectively measured physical activity volume, intensity and pattern. RESULTS: Obese children were significantly less physically active overall than their nonobese counterparts (31,844+/-13,200 vs 41,844+/-10,430 counts/h; 95% confidence interval 4407 to 15592; P=0.001). Similarly the obese children spent less time in physical activity of moderate or greater intensity than the nonobese children (9.9+/-3.9 vs 12.9+/-4.2 min/h; 95% confidence interval 1.15 to 4.80; P=0.002). Hourly patterns of activity indicated a tendency in obese children to be less active than nonobese children at times when activity was more likely to be determined by free choice, particularly outside of school time. CONCLUSIONS: Obese children demonstrated patterns of physical activity that may have contributed to and are likely to sustain their obesity. Minute-by-minute accelerometry is a valuable tool to investigate physical activity patterns in obese children. It can identify periods when intervention to increase activity may be most appropriate and provide an evidence base for specific exercise prescription in primary and secondary care.

The importance of testing for adrenoleucodystrophy in males with idiopathic Addison's disease.

X linked adrenoleucodystrophy (X-ALD) is considered to be a rare cause of Addison's disease, although several small series suggest a high incidence in young Addisonian males. A survey in the south west of England identified 12 male patients diagnosed with Addison's disease in the period 1987-99. In 10 of these (83%) X-ALD was the underlying cause; the other two were of autoimmune aetiology. Five boys had developed Addison's disease subsequent to the diagnosis of X-ALD. Of the remaining five, in three boys the diagnosis of X-ALD was considerably delayed (by six months to two years from that of Addison's disease) and in two it was only made as a result of this survey. We also identified a patient who presented with Addison's disease at the age of 5 years but was only diagnosed as having X-ALD at the age of 34 years; in the interim his diagnosis of adrenomyeloneuropathy had been missed. Our experience highlights the absolute necessity of measuring very long chain fatty acids in all males with idiopathic Addison's disease.

Type 2 diabetes in obese white children.

We report four white adolescents aged 13 to 15 years (three females, one male) from the south and west region of England who presented with type 2 diabetes mellitus associated with significant obesity (body mass index more than +3SDS) in the past two years. Although these are the first reported obese, white cases from the UK to present with diabetes, we believe this clinical scenario will become more prevalent given the epidemic of childhood obesity in this country.

Management of puberty in constitutional delay of growth and puberty.

Constitutional delay of growth and puberty (CDGP) is the most common presenting form of short stature, but no single test can infallibly discriminate CDGP and isolated hypogonadotrophic hypogonadism. Management of puberty in CDGP aims to optimise not only growth maintaining body proportions and improving peak bone mass without impairing growth potential--but also well-being; for example, the distress boys often suffer because of their lack of growth and pubertal progression can affect their school performance and social relationships. Typical sex steroid treatments to induce puberty in boys with CDGP include testosterone (T) enanthate, T undecanoate, mixed T esters, T transdermal patches, and oxandrolone p.o. Compared with other regimens, short-course low-dose depot T i.m. is an effective, practical, safe, well tolerated, and inexpensive regimen. Some unresolved problems in management include optimal timing and dose of sex steroid treatment, the role of GH in CDGP, and the management of CDGP in girls.

Unresolved problems in optimal therapy of pubertal disorders in oncological and bone marrow transplanted patients.

Specialised clinics for the long-term follow-up of survivors from childhood cancer have developed over recent years. The problems encountered among patients who received multiple chemotherapy and radiotherapy can be challenging and require high expertise and close collaboration among different professionals (e.g. oncologists, endocrinologists, radiotherapists, psychologists). Endocrine disorders are often seen, particularly among those who received cranial radiotherapy or gonadotoxic chemotherapy; puberty can be affected and the spectrum of disorders may range from precocious or accelerated puberty to delayed, arrested or even absent pubertal development. Growth impairment can be multifactorial and growth hormone deficiency is an important but probably not the only factor involved. Many questions remain about the optimal management of this group of young patients. In the consensus guidelines that follow the overview an attempt is made to help optimise patients' growth and puberty by suggesting practical clinical approaches to some of the most challenging issues.

The role of IGF-binding proteins in mediating the effects of recombinant human IGF-I on insulin requirements in type 1 diabetes mellitus.

To determine the role of IGF-binding proteins in mediating the direct effects of recombinant human IGF-I on insulin requirements in type 1(insulin-dependent) diabetes mellitus, overnight changes in IGF-I, IGF-II, and IGF-binding protein-1, -2, and -3, collected under euglycemic conditions, were compared in nine subjects after double blind, randomized, sc administration of recombinant human IGF-I (40 microg/kg) or placebo at 1800 h. On both nights a somatostatin analog infusion (300 ng/kg x h) suppressed endogenous GH production, and three timed discrete GH pulses (total, 0.029 IU/kg x night) ensured identical GH levels. After recombinant human IGF-I administration, IGF-I levels and the IGF-I/IGF-binding protein-3 ratio increased [mean +/- SEM:IGF-I, 401 +/- 22 ng/ml; placebo, 256 +/- 20 ng/ml (P = 0.0002); IGF-I, 0.108 +/- 0.006; placebo, 0.074 +/- 0.004 (P = 0.0003), respectively], and insulin requirements decreased (IGF-I, 0.12 +/- 0.03; placebo, 0.23 +/- 0.03 U/kg x min; P = 0.008). The normal within-individual inverse relationships between insulin and IGF-binding protein-1 levels were observed (lag time 2 h: r = -0.34; P < 0.01). Yet despite reduced free insulin levels (8.5 +/- 1.5; placebo, 12.2 +/- 1.2 mU/liter; P = 0.03), IGF-binding protein-1 levels were reduced after recombinant human IGF-I administration (53.7 +/- 6.8; placebo, 82.2 +/- 11.8 ng/ml; P = 0.008). The largest reductions in free insulin levels after recombinant human IGF-I and thus putative improvement in insulin sensitivity occurred in subjects with the smallest increase in the plasma IGF-I/IGF-binding protein-3 ratio (r = 0.7; P = 0.03). Taken together, these data are consistent with the hypothesis that transcapillary movement of IGF-I (perhaps mediated by IGF-binding protein-1), out of the circulation facilitates altered insulin sensitivity. These data have important implications for risk-benefit assessment of recombinant human IGF-I therapy in type 1 diabetes mellitus.

Pancreatic dysfunction in severe obesity.

AIMS: To investigate pancreatic function in children attending an obesity clinic. METHODS: Thirty six children (of which 34 were white) with severe obesity of prepubertal onset (body mass index more than +2 SDS) were reviewed clinically and dysmorphologically, with assessment of pancreatic function. RESULTS: Eight had dysmorphic features and 13 had learning difficulties. Four of 17 prepubertal children had hyperinsulinaemia and seven had hyperproinsulinaemia. All 19 pubertal children had hyperinsulinaemia, 14 had hyperproinsulinaemia, and one had type II diabetes. CONCLUSIONS: Metabolic abnormalities predictive of type II diabetes occur in severely obese white children.

Growth hormone hypersecretion in a girl with neurofibromatosis type 1 and an optic nerve glioma: resolution following chemotherapy.

Growth hormone hypersecretion is extremely rare in childhood. We report a girl with neurofibromatosis type 1, an extensive optic nerve glioma and growth hormone hypersecretion. She was treated with chemotherapy to prevent further extension of her sight-threatening tumour. Three years after chemotherapy her growth hormone hypersecretion has resolved although she has gone on to develop precocious puberty.

Counterregulation during spontaneous nocturnal hypoglycemia in prepubertal children with type 1 diabetes.

OBJECTIVE: To examine counterregulatory responses during spontaneous nocturnal hypoglycemia in prepubertal children with type 1 diabetes. RESEARCH DESIGN AND METHODS: A total of 29 prepubertal patients with type 1 diabetes underwent two overnight profiles. Data were analyzed from 16 children (median [range] 8.7 [5.9-12.9] years of age) with a night of hypoglycemia and a nonhypoglycemic night. Children hypoglycemic (< 3.5 mmol/l) on night 1 were given 25% extra carbohydrate as uncooked cornstarch with their usual evening snack on night 2 to avoid hypoglycemia. Glucose, growth hormone, and cortisol were measured every 15 min, catecholamines every 30 min, and glucagon, pancreatic polypeptide, insulin, and ketones every 60 min. A group of 15 healthy control subjects, aged 9.5 (5.6-12.1) years, underwent one overnight profile. RESULTS: Median duration of hypoglycemia was 225 (30-630) min, and glucose nadir was 2.0 (1.2-3.3) mmol/l. Insulin levels were not different on the two nights (P = 0.9, analysis of variance), but children with diabetes had higher insulin levels than normal control subjects between 2300 and 0300, maximal at 0200 (mean +/- SEM 57.4 +/- 5.7 vs. 31.6 +/- 5.0 pmol/l, P = 0.002). Peak epinephrine was higher on the night of hypoglycemia (0.98 [0.52-2.09] nmol/l) versus nonhypoglycemia (0.32 [0.21-0.62] nmol/l), P = 0.001, but norepinephrine (1.29 [1.07-2.64] vs. 1.26 [1.04-1.88] nmol/l, P = 0.5), glucagon (93 [64.2-125.6] vs. 100.5 [54.6-158] ng/l, P = 0.6), pancreatic polypeptide (410.2 [191-643.2] vs. 270.8 [158.2-777.8] ng/l, P = 0.5), and cortisol (513 [300-679] vs. 475 [235-739] nmol/l, P = 0.6) were not different. Glucose threshold for epinephrine release was very low, 1.9 +/- 0.2 mmol/l. There was a short-lived rise in growth hormone from 75-105 min after onset of hypoglycemia, maximal at 90 min (7.8 +/- 1.2 vs. 3.5 +/- 0.9 ng/ml, P = 0.02). CONCLUSIONS: The prolonged nature of nocturnal hypoglycemic episodes may be explained in part by defective counterregulation. The risk of nocturnal hypoglycemia needs to be reduced before intensification of insulin therapy can be contemplated in this age-group.

Islet amyloid polypeptide decreases the effects of insulin-like growth factor-I on glucose transport and glycogen synthesis in skeletal muscle.

Previous studies have shown that islet amyloid polypeptide (IAPP) is co-secreted with insulin from the beta-cell. IAPP reduces insulin-stimulated rates of glycogen synthesis in skeletal muscle but the mechanisms are unclear. Insulin-like growth factor I (IGF-I) is an important regulator of glucose metabolism in skeletal muscle and acts through its own receptor, which has many structural and functional similarities with the insulin receptor. Despite this, the effects of IGF-I on glucose utilization are not identical to those of insulin. The aim of the study was to determine the effects of IAPP on IGF-I-stimulated rates of glucose transport and metabolism (measured by 3-O-methyl[3H]glucose and [U-14C]glucose, respectively) in rat soleus muscle, and compare them with those simulated by insulin. IAPP (10 nM) decreased the sensitivity of 3-O-methylglucose transport, the flux of glucose to hexosemonophosphate and the sensitivity of glycogen synthesis to IGF-I. In contrast, IAPP had no effect on IGF-I-stimulated rates of lactate formation (i.e., glycolysis). IAPP decreased the sensitivity of 3-O-methylglucose transport and glycogen synthesis to insulin. It is concluded that IAPP blunts the stimulation of glucose uptake and deposition by IGF-I or insulin in skeletal muscle. These observations expand those made initially for IAPP and insulin and suggest that IAPP affects IGF-I- or insulin-stimulated glucose metabolism in muscle by a mechanism which is common for both hormones. These experiments may serve as a framework for future studies in order to clarify the mechanisms by which IAPP affects glucose metabolism in skeletal muscle.