Peripheral nerve function is increasingly impaired during puberty in adolescents with type 1 diabetes

Neurological dysfunction screening in a cohort of adolescents with type 1 diabetes: a six-year follow-up

Aims

Diabetic neuropathy (DN) is one of the most insidious microvascular complications in patients with type 1 diabetes (T1DM) and initial signs may appear during childhood. The aim of this study is to evaluate associations between the Nerve Conduction Studies (NCS) outcomes at enrollment with neuropathy screening questionnaires performed six years later in a cohort of asymptomatic adolescents followed up until early adulthood, affected by T1DM.

Methods

We performed NCS in a cohort of seventy-two adolescents with T1DM and eighteen healthy controls. Six years later, screening questionnaires for DN were proposed: Michigan Neuropathy Screening Instrument (MNSI, specific for symptoms of somatic dysfunction), Composite Autonomic Symptom Score 31 (COMPASS 31, specific for abnormalities of the autonomic component) and Clarke questionnaire (perception of hypoglycemia). Thirty-two TD1M subjects agreed to participate in the follow-up; main clinical-metabolic parameters, including the number of episodes of hypoglycemia in the past twelve months, were collected.

Results

11.8% of subjects showed changes compatible with DN through the MNSI questionnaire, while 41% declared a reduced perception of hypoglycemia on the Clarke questionnaire. No significant correlation was observed between the clinical-metabolic parameters or altered response to NCS and scores of MNSI and COMPASS 31 questionnaires. On the other hand, an association was observed between NCS abnormalities and a high number of hypoglycemic events after six years (97-fold increased risk, p = 0.009).

Conclusion

The frequency of somatic alterations in the study population is 11.8%, whereas the frequency of symptoms correlated with autonomic damage is about 41%. An autonomic impairment recorded at NCS may represent a six-year risk factor for increased hypoglycemic episodes, even if more extensive studies are needed to investigate this possible relationship further.

Neuropathy in paediatric type 1 diabetes mellitus - clinical characterization and analysis of risk factors in the diabetes prospective follow-up registry DPV (Diabetes-Patienten-Verlaufsdokumentation)-registry

OBJECTIVES

Data on the prevalence, clinical features and risk factors associated with paediatric diabetic neuropathy (DN) are scarce.

METHODS

We retrospectively analysed data from the DPV registry, including patients under 20 years of age, treated for type 1 diabetes mellitus (T1D) between 2005 and 2021. Patients with non-diabetic neuropathy were excluded. Data came from centres in Austria, Germany, Luxembourg and Switzerland.

RESULTS

1,121 of the 84,390 patients included had been diagnosed with DN. Univariate analysis showed patients with DN to be older and predominantly female, with a longer duration of T1D, higher insulin dosages per kg and day, lower rates of insulin pump therapy, higher postprandial glucose-, higher HbA_1c-and higher cholesterol levels, and higher diastolic and systolic blood pressure values. There was also a larger proportion of smokers and higher prevalence of diabetic retinopathy. Median duration of diabetes at diagnosis of DN was 8.3 years. Multivariable analysis, adjusted for demographics revealed an increased risk for DN among female patients and those who were older, underweight (BMI-SDS), smoked cigarettes or had a longer duration of T1D or higher levels of HbA_1c and postprandial blood glucose. The presence of retinopathy and higher cholesterol levels were also linked to increased risk while not-using insulin pump therapy was not.

CONCLUSIONS

DN can develop after just a short duration of T1D. Prevention may be achieved by a lowering of HbA_1c-and postprandial glucose levels through improved glycaemic control. This warrants further investigation. The slight female predominance suggests further hormonal and genetic etiological factors.

Point Prevalence of Peripheral Neuropathy in Children and Adolescents with Type 1 Diabetes Mellitus

OBJECTIVE

To assess the point prevalence of peripheral neuropathy (PN) in children with type 1 diabetes mellitus (T1DM) and to determine their predictors.

METHODS

In this cross-sectional study, children aged 8-18 y with T1DM on insulin therapy for > 2 y and free from acute complications were enrolled. All participants were evaluated for symptoms of PN with diabetic neuropathy symptom (DNS) score and underwent a detailed neurological examination. Assessment of nerve dysfunction was done using nerve conduction studies (NCS). The disease-related factors that increase the risk of PN were determined.

RESULTS

Fifty children (52% boys) were enrolled with mean age of 12.2 ± 2.8 y and duration of diabetes 5.1 ± 2.1 y. No subject had clinical evidence or DNS score suggestive of PN. Twenty-eight (56%) children demonstrated subclinical neuropathy on NCS. Proportion of children with pure motor, pure sensory, and mixed motor-sensory neuropathy was 40%, 2%, and 14%, respectively. The peroneal nerve was the most common motor nerve affected. Poor glycemic control (HbA1c > 9%) and longer duration of diabetes (> 5 y) were significantly associated with the risk of PN (p value < 0.05).

CONCLUSION

A large proportion of children with T1DM have subclinical PN. Poor glycemic control and longer duration of diabetes are risk factors for nerve dysfunction. Neurophysiological studies should be performed in these children to facilitate early detection.

The natural history of emerging diabetic retinopathy and microalbuminuria from prepuberty to early adulthood in Type 1 diabetes: A 19-year prospective clinical follow-up study

OBJECTIVE

To evaluate the impact of long-term glycaemic control and glycaemic variability on microvascular complications in adolescents and young adults with childhood-onset Type 1 diabetes.

METHODS

Twenty-six participants took part in a prospective follow-up study. We used univariate generalised estimating equations (GEE) analysis with first-order autoregressive AR(1) covariance structure for repeated measurements to evaluate the relationship between emerging diabetic retinopathy (DR) and each single explanatory variable, namely age at developmental stages from late prepuberty until early adulthood, duration of diabetes and long-term HbA_1c . Thereafter, the simultaneous effect of these three explanatory variables to DR was analysed in a multivariate model.

RESULTS

Twenty-five participants developed DR by early adulthood after a median diabetes duration of 16.2 years (range 6.3-24.0). No participants had DR during prepuberty. Each of the three variables was independently associated with emerging DR: age (OR 1.47, 95% CI to 1.25 to 1.74, p < 0.001) stronger than diabetes duration (OR 1.42, 95% CI 1.23 to 1.63, p < 0.001) and HbA_1c (OR 1.02, 95% CI 1.001 to 1.05, p = 0.041) in this population. In the multivariate analysis of these three explanatory variables, only age was associated with DR (adjusted OR 1.52, 95% CI 1.10 to 2.10, p = 0.012).

CONCLUSIONS

The emergence of DR during adolescence and early adulthood is not rare and increases with age in patients with deteriorating metabolic control during puberty and thereafter. This underpins the need to prevent deterioration of glycaemic control from taking place during puberty-seen again in this follow-up study-in children with diabetes.

Large fibre, small fibre and autonomic neuropathy in adolescents with type 1 diabetes: A systematic review

AIMS

To estimate the prevalence of neuropathy in adolescents with type 1 diabetes.

METHODS

Systematic collection of published studies exploring the prevalence of large fibre neuropathy (LFN), small fibre neuropathy (SFN), and autonomic neuropathy in adolescents with type 1 diabetes. Following prospective registration (Prospero CRD42020206093), PubMed, EMBASE, and Cochrane Library were searched for studies from 2000 to 2020. PICO framework was used in the selection process (Population: adolescents aged 10-19 years with type 1 diabetes; Intervention: diagnostic methods for neuropathy; Comparison: reference data; Outcome: data on prevalence or comparison). Data were extracted concerning study quality based on available data and established methods for determining and diagnosing various neuropathy types.

RESULTS

From 2,017 initial citations, 27 studies (7589 participants) fulfilled eligibility criteria. The study population (47% males) had a diabetes duration between 4.0 and 10.6 years, and HbA1c level between 7.3 and 10.8%, 56-95 mmol/mol. The prevalence of LFN, based on nerve conduction studies, was 10-57%. Based on other tests for neuropathy, the prevalence of LFN and SFN was 12-62%, and that of cardiac autonomic neuropathy was 12-75%.

CONCLUSION

The described prevalence of neuropathy in adolescents with type 1 diabetes varied, which can be methodological due to different screening methods and classifications of neuropathy.

Peripheral and Autonomic Neuropathy Status of Young Patients With Type 1 Diabetes Mellitus at the Time of Transition From Pediatric Care to Adult-Oriented Diabetes Care

INTRODUCTION

The prevalence of neuropathic lesions in young patients with type 1 diabetes mellitus (T1DM) at the time of transition from pediatric care to adult-oriented diabetes care is poorly studied. A comparative study with healthy volunteers to assess the possible neuropathic condition of this special population and to identify the potential early screening needs has not been performed yet. The results may provide important feedback to pediatric diabetes care and a remarkable baseline reference point for further follow up in adult diabetes care.

PATIENTS AND METHODS

Twenty-nine young patients with T1DM [age: 22.4 ± 2.9 years; HbA1c: 8.5 ± 2.1%, diabetes duration: 12.2 ± 5.8 years; (mean ± SD)] and 30 healthy volunteers (age: 21.5 ± 1.6 years; HbA1c: 5.3 ± 0.3%) were involved in the study. Autonomic function was assessed by standard cardiovascular reflex tests. Complex peripheral neuropathic testing was performed by Neurometer^®, Neuropad^®-test, Tiptherm^®, Monofilament^®, and Rydel-Seiffer tuning fork tests.

RESULTS

T1DM patients had significantly higher diastolic blood pressure than controls (80 ± 9 vs. 74 ± 8 mmHg, p < 0.01), but there was no significant difference in systolic blood pressure (127 ± 26 vs. 121 ± 13 mmHg). Cardiovascular reflex tests had not revealed any significant differences between the T1DM patients and controls. No significant differences with Neurometer^®, Neuropad^®-test, and Monofilament^® were detected between the two groups. The vibrational sensing on the radius on both sides was significantly impaired in the T1DM group compared to the controls with Rydel-Seiffer tuning fork test (right: 7.5 ± 1.0 vs. 7.9 ± 0.3; left: 7.5 ± 0.9 vs. 7.9 ± 0.3, p < 0.05). The Tiptherm^®-test also identified a significant impairment in T1DM patients (11 sensing failures vs. 1, p < 0.001). In addition, the neuropathic complaints were significantly more frequently present in the T1DM patient group than in the controls (9 vs. 0, p < 0.01).

CONCLUSION

In this young T1DM population, cardiovascular autonomic neuropathy and cardiac morphological alterations could not be found. However, Rydel-Seiffer tuning fork and Tiptherm^®-tests revealed peripheral sensory neurological impairments in young T1DM patients at the time of their transition to adult diabetes care.

Diabetic neuropathy in children and adolescents with type 1 diabetes mellitus: Diagnosis, pathogenesis, and associated genetic markers

Diabetic neuropathy (DN) is a common long-term complication of type 1 (T1D) and type 2 (T2D) diabetes mellitus, with significant morbidity and mortality. DN is defined as impaired function of the autonomic and/or peripheral nervous system, often subclinical, particularly in children and adolescents with T1D. Nerve conduction studies (NCS) and skin biopsies are considered gold-standard methods in the assessment of DN. Multiple environmental and genetic factors are involved in the pathogenesis of DN. Specifically, the role of metabolic control and glycemic variability is of paramount importance. A number of recently identified genes, including the AKR1B1, VEGF, MTHFR, APOE, and ACE genes, contribute significantly in the pathogenesis of DN. These genes may serve as biomarkers to predict future DN development or treatment response. In addition, they may serve as the basis for the development of new medications or gene therapy. In this review, the diagnostic evaluation, pathogenesis, and associated genetic markers of DN in children and adolescents with T1D are presented and discussed.

Early corneal nerve fibre damage and increased Langerhans cell density in children with type 1 diabetes mellitus

Corneal confocal microscopy (CCM) has been used to identify corneal nerve damage and increased Langerhans cell (LC) density in adults with Type 1 diabetes mellitus (T1DM). The purpose of this study was to evaluate whether corneal confocal microscopy can identify early corneal nerve damage and change in LC density in children and adolescents with T1DM. 64 participants with T1DM (age-14.6 ± 2.5 years, duration of diabetes-9.1 ± 2.7 years, HbA1c-75.66 ± 2.53 mmol/mol [9.1 ± 1.8%]) and 48 age-matched healthy control subjects underwent CCM. Sub-basal corneal nerve morphology and the density of mature and immature LCs was quantified. Corneal nerve fibre length and branch density were lower, whilst fibre density and tortuosity did not differ and both immature and mature LC density was significantly higher in T1DM compared to control subjects. There was no association between HbA1c and duration of diabetes with nerve fibre parameters or LC's density. Children and adolescents with T1DM demonstrate early immune activation and nerve degeneration.

Electrophysiological Characterization of Neuropathy Complicating Type 1 Diabetes Mellitus

Diabetic peripheral neuropathy (DPN) involves sensory and motor nerves, resulting in demyelination as well as axonal degeneration. This study was conducted to describe the pattern of lower limb nerve involvement in children with type 1 diabetes mellitus (DM) based on the parameters of nerve conduction study (NCS). This cross-sectional study recruited 50 children with type 1 DM having mean disease duration of 4.92 ± 3.84 years who attended the referred clinic in Sudan Childhood Diabetes Center. Their mean age was 15.00 ± 2.19 years, 42% were males, and 58% were females. Twenty six matched healthy control subjects were involved; their mean age was 13.88 ± 2.46 years, 38.46% were males, and 61.54% were females. Bilateral NCS of the sensory and motor lower limb nerves was performed using Medelec Synergy machine. Interpretation of the patients' results was based on our own control reference values. Data was analysed using IBM SPSS statistics. Out of the 50 diabetic patients, 44 (88%) had electrophysiological evidence of peripheral neuropathy (abnormalities in at least two of the electrophysiological parameters). The majority (68.2%) had motor involvement and 31.8% had sensorimotor, while none of them (0%) had pure sensory involvement. Regarding abnormal NCS parameters (conduction velocity vs. amplitude of the compound action potential), conduction slowing feature predominated in 61.4% and only few (6.8%) showed amplitude reduction, while 31.8% showed mixed features. The most frequently affected nerve was the common peroneal, followed by posterior tibial, and the least was the sural nerve. The most sensitive parameter was the common peroneal conduction velocity. Motor precedes sensory nerve involvement. The most frequent neurophysiological abnormality was the conduction slowing, and the common peroneal was the most vulnerable nerve. These findings signify generation of a protocol for early screening of neuropathy in children with type 1 diabetes.

Neurological Complications of Endocrine Disease

The endocrine system is a complex group of organs and glands that relates to multiple other organs and systems in the body with the ultimate goal of maintaining homeostasis. This complex network functions through hormones excreted by several glands and released in the blood, targeting different body tissues and modulating their function. Any primary disorders affecting the endocrine glands and altering the amount of hormones synthesized and released will lead to disruption in the functions of multiple organs. The central nervous system of a developing child is particularly sensitive to endocrine disorders. A variety of neurological manifestations have been described as features of several endocrine diseases in childhood. Their knowledge may contribute to an early diagnosis of a particular endocrine condition, especially when more typical features are not present yet. In this article, we discuss specific neurological manifestations found in various endocrine disorders in children.

The prevalence of early subclinical somatic neuropathy in children and adolescents with Type 1 diabetes mellitus and its association with the persistence of autoantibodies to glutamic acid decarboxylase (GAD) and islet antigen-2 (IA-2)

AIM

To evaluate the prevalence of early somatic neuropathy in children and adolescents with Type 1 diabetes mellitus (Type 1 DM) and its association with the presence of glutamic acid decarboxylase and islet antigen-2 autoantibodies (GADA and IA-2A).

METHODS

A cross-sectional study was conducted in a hospital-based cohort of pediatric Type 1 DM patients (n=85, mean(±SD) age: 13.5±3.4years, mean(±SD) disease duration 5.5±3.4years). Peripheral neuropathy was assessed with nerve conduction studies (NCS). GADA and IA-2A titers were measured with radioligand assays.

RESULTS

Among the study population, 34.1% had at least one abnormal electrophysiological parameter, although predominantly asymptomatic. The highest rates of abnormality were detected in sensory peroneal nerve (25.9%) followed by sural nerve (15.3%). Affected patients were not different in terms of age, diabetes duration or glycaemic control. Among the participants, 62.4% had positive GADA, 58.8% positive IA-2A and 42.4% double antibody positivity. Abnormal NCS correlated neither with GADA nor with IA-2A levels or positivity. However lower sensory nerve action potential in the peroneal nerve, indicative of early axonal dysfunction, was observed in patients with GADA or IA-2A positivity. Absence of both antibodies was associated with better action potentials in all the examined nerves of the lower limbs.

CONCLUSIONS

Impaired indices of subclinical peripheral primarily sensory neuropathy were present among one third of Type 1 DM children and adolescents, with no impact of diabetes duration or glycaemic control. GADA and IA-2A seem to be involved in the development of axonal degeneration, in a pathway which remains to be identified.

Atypical neurologic presentations of new onset type 1 diabetes mellitus in pediatric age group: a report of five unusual cases and review of the literature

Type 1 diabetes mellitus (T1DM) is one of the most common chronic diseases in childhood and is caused by insulin deficiency resulting from the autoimmune destruction of insulin producing beta cells of the pancreas. Most children in the US with new onset T1DM present with the classic signs and symptoms of hyperglycemia and 30% with diabetic ketoacidosis (DKA). Neurologic manifestations are relatively rare and mostly include lethargy, decreased level of consciousness, and coma as a result of DKA. In this article, five cases of new onset T1DM with exceedingly rare or unreported neurologic manifestations in the pediatric age group are presented, along with a review of the literature.

Autonomic neuropathy in diabetes mellitus

Diabetic autonomic neuropathy (DAN) is a serious and common complication of diabetes, often overlooked and misdiagnosed. It is a systemic-wide disorder that may be asymptomatic in the early stages. The most studied and clinically important form of DAN is cardiovascular autonomic neuropathy defined as the impairment of autonomic control of the cardiovascular system in patients with diabetes after exclusion of other causes. The reported prevalence of DAN varies widely depending on inconsistent definition, different diagnostic method, different patient cohorts studied. The pathogenesis is still unclear and probably multifactorial. Once DAN becomes clinically evident, no form of therapy has been identified, which can effectively stop or reverse it. Prevention strategies are based on strict glycemic control with intensive insulin treatment, multifactorial intervention, and lifestyle modification including control of hypertension, dyslipidemia, stop smoking, weight loss, and adequate physical exercise. The present review summarizes the latest knowledge regarding clinical presentation, epidemiology, pathogenesis, and management of DAN, with some mention to childhood and adolescent population.

Type 1 diabetes and cardiovascular disease

The presence of cardiovascular disease (CVD) in Type 1 diabetes largely impairs life expectancy. Hyperglycemia leading to an increase in oxidative stress is considered to be the key pathophysiological factor of both micro- and macrovascular complications. In Type 1 diabetes, the presence of coronary calcifications is also related to coronary artery disease. Cardiac autonomic neuropathy, which significantly impairs myocardial function and blood flow, also enhances cardiac abnormalities. Also hypoglycemic episodes are considered to adversely influence cardiac performance. Intensive insulin therapy has been demonstrated to reduce the occurrence and progression of both micro- and macrovascular complications. This has been evidenced by the Diabetes Control and Complications Trial (DCCT) / Epidemiology of Diabetes Interventions and Complications (EDIC) study. The concept of a metabolic memory emerged based on the results of the study, which established that intensified insulin therapy is the standard of treatment of Type 1 diabetes. Future therapies may also include glucagon-like peptide (GLP)-based treatment therapies. Pilot studies with GLP-1-analogues have been shown to reduce insulin requirements.

Validity of the neurological examination in diagnosing diabetic peripheral neuropathy

The aim of this study was to evaluate the prevalence of diabetic peripheral neuropathy in children and adolescents with type 1 diabetes mellitus and examine whether the neurological examination validly diagnoses diabetic peripheral neuropathy as compared with the gold standard of nerve conduction velocity in these patients. Nerve conduction velocity was measured in an unselected consecutive series of patients aged 8-18 years who had been suffering from type 1 diabetes mellitus for at least 1 year. For the neurological examination, neuropathy disability scores and neuropathy sign scores were used. Of the 39 patients, six (15%) had clinically evident diabetic peripheral neuropathy, whereas nerve conduction velocity testing revealed diabetic peripheral neuropathy in 15 (38%) patients. Sensitivity and specificity of the neurological examination for the diagnosis of diabetic peripheral neuropathy were 40% and 100%, respectively. The corresponding positive and negative predictive values were 100% and 72.7%, respectively. This conclusions from this study are that in children and adolescents with type 1 diabetes mellitus, diabetic peripheral neuropathy is highly prevalent, but in the majority of patients it is subclinical. Sensitivity and negative predictive values of the neurological examination are low. Therefore, routine nerve conduction velocity measurement for the assessment of diabetic peripheral neuropathy appears to be warranted in these patients.

The evaluation of peripheral neuropathy in youth with type 1 diabetes

Of 151 youth with type 1 diabetes who were screened for peripheral neuropathy, and received nerve conduction studies, 11% were diagnosed with Diabetic Peripheral Neuropathy (DPN). DPN can occur in young children, with short diabetes duration, and good diabetes control. National guidelines for screening children for DPN should be developed.

Prospectively determined impact of type 1 diabetes on brain volume during development

OBJECTIVE

The impact of type 1 diabetes mellitus (T1DM) on the developing central nervous system is not well understood. Cross-sectional, retrospective studies suggest that exposure to glycemic extremes during development is harmful to brain structure in youth with T1DM. However, these studies cannot identify brain regions that change differentially over time depending on the degree of exposure to glycemic extremes.

RESEARCH DESIGN AND METHODS

We performed a longitudinal, prospective structural neuroimaging study of youth with T1DM (n = 75; mean age = 12.5 years) and their nondiabetic siblings (n = 25; mean age = 12.5 years). Each participant was scanned twice, separated by 2 years. Blood glucose control measurements (HbA(1c), glucose meter results, and reports of severe hypoglycemia) were acquired during the 2-year follow-up. Sophisticated image registration algorithms were performed, followed by whole brain and voxel-wise statistical analyses of the change in gray and white matter volume, controlling for age, sex, and age of diabetes onset.

RESULTS

The T1DM and nondiabetic control (NDC) sibling groups did not differ in whole brain or voxel-wise change over the 2-year follow-up. However, within the T1DM group, participants with more hyperglycemia had a greater decrease in whole brain gray matter compared with those with less hyperglycemia (P < 0.05). Participants who experienced severe hypoglycemia had greater decreases in occipital/parietal white matter volume compared with those with no severe hypoglycemia (P < 0.05) and compared with the NDC sibling group (P < 0.05).

CONCLUSIONS

These results demonstrate that within diabetes, exposure to hyperglycemia and severe hypoglycemia may result in subtle deviation from normal developmental trajectories of the brain.

Mitigating micro-and macro-vascular complications of diabetes beginning in adolescence

Diabetes is a chronic disorder, which manifests when insulin levels or resistance to insulin action becomes insufficient to control systemic glucose levels. Although the number of available agents to manage diabetes continues to expand rapidly, the maintenance of euglycemia by individuals with diabetes remains a substantial challenge. Unfortunately, many patients with type 1 and type 2 diabetes will ultimately experience diabetes complications. These complications result from the toxic effects of chronic hyperglycemia combined with other metabolic derangements that afflict persons with diabetes. This review will present a comprehensive look at the complications of diabetes, the risk factors for their progression, the mechanistic basis for their development, and the clinical approach to screening for, preventing, and treating these sequelae. In addition, since diabetes is commonly diagnosed in childhood, we will provide a special focus on the care of the adolescent patient.

Regional brain volume differences associated with hyperglycemia and severe hypoglycemia in youth with type 1 diabetes

OBJECTIVE

Despite interest in the effects of type 1 diabetes on the developing brain, structural brain volumes in youth with this disease have not previously been examined. This study is the first to quantify regional brain volume differences in a large sample of youth with diabetes.

RESEARCH DESIGN AND METHODS

Magnetic resonance images (MRIs) were acquired from youth with diabetes (n = 108) and healthy sibling control subjects (n = 51) aged 7-17 years. History of severe hypoglycemia was assessed by parent interview and included seizure, loss of consciousness, or requiring assistance to treat. A1C values since diagnosis were obtained from medical records; median A1C was weighted by duration of disease. Voxel-based morphometry was used to determine the relationships of prior hypo- and hyperglycemia to regional grey and white matter volumes across the whole brain.

RESULTS

No significant differences were found between diabetic and healthy control groups in grey or white matter. However, within the diabetic group, a history of severe hypoglycemia was associated with smaller grey matter volume in the left superior temporal region. Greater exposure to hyperglycemia was associated with smaller grey matter volume in the right cuneus and precuneus, smaller white matter volume in a right posterior parietal region, and larger grey matter volume in a right prefrontal region.

CONCLUSIONS

Qualitatively different relationships were found between hypo- and hyperglycemia and regional brain volumes in youth with type 1 diabetes. Future studies should investigate whether these differences relate to cognitive function and how these regions are affected by further exposure.

Early Diabetes-Related Complications in Adolescents

Micro- and macrovascular complications account for the major part of the morbidity and mortality associated with diabetes developing in childhood. Although advanced complications are exceptionally rare in the adolescent age group, it is during this phase that the progression of risk may accelerate. A number of potentially important factors have been identified which might contribute to risk of complication development: some provide insights into the genetics of these complications, while others are potentially modifiable, such as metabolic control, hypertension, smoking, obesity and hyperlipidemia. Recently, both consensus and evidence-based guidelines have been developed to guide those involved in the care of adolescents with diabetes in the prevention, screening and management of early diabetes-related complications in this vulnerable population. This article reviews the literature that underpins the available guidelines and stresses the pivotal role of excellent metabolic control in complication prevention.

Subclinical peripheral neuropathy in type 1 diabetic adolescents and its relationship with metabolic control

Professional management of paediatric diabetology, according to consensus guidelines, involves the screening of micro-vascular complications at puberty. The subclinical form of peripheral neural dysfunction in diabetic teenagers is reported with a frequency of 50-88%, by different authors. The purpose of this study was to evaluate the frequency of subclinical distal neuropathy (DSMN) in type 1 diabetic pediatric patients during the second decade of life, and its relationship with metabolic control. The Endocrinology Department and the Neurology-Physiology Laboratory of the Pediatric Clinic in Belgrade carried out a longitudinal follow-up study (lasting 18 months, beginning in November 2000) on a selection of patients with poor metabolic control. During routine clinical treatment, patients were evaluated using the electrophysiological diagnostic method on peripheral neural dysfunction, a subclinical form of neuropathy. Metabolic control was manifested through HbA1c levels, measured every 3 months, using ion-exchange chromatography. Finally, here is the data collected from the clinical follow-up investigation of 60 children, aged 13-19 (median 1S.S?2.2), with duration of diabetes from 2-16 years (median b.3?3.b), and on the following therapies: 43 CT-conventional and 17 IIT-intensive, and insulin dose/day, median 1.02 (0.6-2.1) U/kg. Detected DSMN parameters at the beginning and at the end of the study were also noted. DSMN frequency was positive, at 64% for HbA1c of 9.44; DSMN dysfunction was reversed in 5% of the patients, for HbA1c of 10.17; the worst result was the progression of DSMN at 6.7% for HbA1c of 10.52; 6.7% had negative DSMN, with improved metabolic control, for HbA1c of 8.4; 15% of the examinations were unfinished (+/*). ANOVA statistical analysis showed a significant statistical relationship between metabolic control (HbA1c levels) and DSMN neuropathy (sig. 0.043, p<0.05). There was no significant relationship between the reversion of DSMN and improved HbA1c, although a numeric distinction did exist. On the clinical aspect, there was a significant relationship between insulin dosage and age (p<0.01, sig. 0.007). This data demonstrates the influence of metabolic regulation on neuropathy. Better metabolic control can slow the progression of subclinical peripheral neural dysfunction (DSMN) in diabetic children.

Diabetic neuropathy in children and adolescents

Diabetic neuropathy (DN) represents a major complication of type 1 diabetes mellitus (T1DM) but there is considerable uncertainty as to its incidence, prevalence, diagnosis and prognosis in pediatric population. Generally, DN is classified as polyneuropathy, focal neuropathy and autonomic neuropathy. The latter seems to be detectable even in asymptomatic children and adolescents with diabetes and is associated with the most serious consequences, such as hypoglycemia unawareness and cardiovascular dysfunction. A near-normal control of blood glucose in the early years after onset of diabetes may delay the development of clinically significant nerve impairment and, therefore, children and adolescents with diabetes represent a critical target for primary prevention of this complication. The aim of this review is to focus on the main clinical, epidemiological and prognostic aspects of DN in children and adolescents with T1DM. Etiopathogenetic theories and diagnostic tools are also reviewed from in a pediatric perspective.

Cardiovascular autonomic reactivity is decreased in adolescents with Type 1 diabetes

AIMS

To characterize autonomic nervous system function by means of the heart rate and blood pressure responses to various stimuli in relation to pubertal maturation in patients with Type 1 diabetes mellitus (DM).

METHODS

One hundred out of 138 eligible patients at the Out-patient Diabetes Clinic and 100 healthy control subjects were examined in terms of cardiovascular parameters at rest, during deep breathing and when standing. Heart rate variability was analysed with time domain,frequency domain and fractal dimension parameters. Tanner pubertal staging was performed before the examinations.

RESULTS

The time domain parameters of heart rate variability at rest or during standing did not significantly differ between the patients and controls in total or at pubertal stages. In the spectral analysis of heart rate variability the very low frequency band was decreased in the patients during standing (P = 0.023).The increase in the very low frequency (P = 0.013)and low frequency (P = 0.031) spectral powers upon changing from a supine position to standing was attenuated in the patients in total, while no significant differences were observed within the Tanner pubertal stages between patients and controls. Heart rate variability during deep breathing was decreased in the patients with distal polyneuropathy (P = 0.006).

CONCLUSIONS

Although cardiovascular integrity is in the main well preserved in adolescent patients with Type 1 DM, these patients are prone to attenuated autonomic nervous system reactivity.

Current literature in diabetes

In order to keep subscribers up-to-date with the latest developments in their field, John Wiley & Sons are providing a current awareness service in each issue of the journal. The bibliography contains newly published material in the field of diabetes/metabolism. Each bibliography is divided into 17 sections: 1 Books, Reviews & Symposia; 2 General; 3 Genetics; 4 Epidemiology; 5 Immunology; 6 Prediction; 7 Prevention; 8 INTERVENTION: a&rpar General; b&rpar Pharmacology; 9 Pathology: a&rpar General; b&rpar Cardiovascular; c&rpar Neurological; d&rpar Renal; 10 Endocrinology & Metabolism; 11 Nutrition; 12 Animal Studies; 13 Techniques. Within each section, articles are listed in alphabetical order with respect to author (9 Weeks journals - Search completed at 1st Aug 2001)