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

Diabetes and neurodegeneration in the brain

Although an association between diabetes mellitus (DM) and cognitive dysfunction has been recognized for a century, it is often not considered as a complication of DM and remains under-recognized. Cognitive dysfunction, usually present as mild cognitive impairment, can occur with either type 1 or type 2 DM. Both forms of DM contribute to accelerated cerebral atrophy and to the presence of heightened white matter abnormalities. These effects are noted most at the two extremes of life, in childhood and in the advanced years. The cognitive spheres most affected include attention and executive function, processing speed, perception, and memory. Although DM is unlikely to lead to frank dementia, its ability to exacerbate existing neurodegenerative processes, such as Alzheimer disease, will impact tremendously upon our society in the upcoming decades as our population ages. This chapter describes the clinical impact of DM upon the brain, along with discussion of the potential therapeutic avenues to be discovered in the coming decades. We need to prepare for better preventative and therapeutic management of this cerebral neurodegenerative condition.

Gray matter alterations and correlation of nutritional intake with the gray matter volume in prediabetes

The neurophysiology of prediabetes plays an important role in preventive medicine. The dysregulation of glucose metabolism is likely linked to changes in neuron-related gray matter. Therefore, we designed this study to investigate gray matter alterations in medication-naive prediabetic patients. We expected to find alterations in the gray matter of prediabetic patients.A total of 64 prediabetic patients and 54 controls were enrolled. All subjects received T1 scans using a 3-T magnetic resonance imaging machine. Subjects also completed nutritional intake records at the 24-hour and 3-day time points to determine their carbohydrate, protein, fat, and total calorie intake. We utilized optimized voxel-based morphometry to estimate the gray matter differences between the patients and controls. In addition, the preprandial serum glucose level and the carbohydrate, protein, fat, and total calorie intake levels were tested to determine whether these parameters were correlated with the gray matter volume.Prediabetic patients had lower gray matter volumes than controls in the right anterior cingulate gyrus, right posterior cingulate gyrus, left insula, left super temporal gyrus, and left middle temporal gyrus (corrected P < 0.05; voxel threshold: 33). Gray matter volume in the right anterior cingulate was also negatively correlated with the preprandial serum glucose level gyrus in a voxel-dependent manner (r = -0.501; 2-tailed P = 0.001).The cingulo-temporal and insula gray matter alterations may be associated with the glucose dysregulation in prediabetic patients.

Tight Glycemic Control in the Pediatric Intensive Care Unit

Hyperglycemia is a common complication in critically ill, nondiabetic children. Four large pediatric randomized controlled trials of tight glycemic control (TGC) have been conducted to date with contradicting results. This review will highlight the design and outcomes of these trials and other relevant studies to provide an overview of the advantages and disadvantages of TGC for different populations at risk of hyperglycemia along with future directions for research.

Academic abilities and glycaemic control in children and young people with Type 1 diabetes mellitus

AIMS

To determine if children and young people aged < 23 years with Type 1 diabetes differ in academic ability from age-matched control subjects without Type 1 diabetes and whether academic scores are related to glycaemic control.

METHODS

Using a cross-sectional study design, we administered cognitive and academic tests (Woodcock-Johnson III Spatial Relations, General Information, Letter-Word Recognition, Calculation and Spelling tests) to young people with Type 1 diabetes (n=61) and control subjects (n=26) aged 9-22 years. The groups did not differ in age or gender. Participants with Type 1 diabetes had a disease duration of 5-17.7 years. History of glycaemic control (HbA1c , diabetic ketoacidosis and severe hypoglycaemic episodes) was obtained via medical records and interviews.

RESULTS

The participants with Type 1 diabetes had a lower mean estimated verbal intelligence (IQ) level compared with those in the control group (P=0.04). Greater exposure to hyperglycaemia over time was associated with lower spelling abilities within the group with Type 1 diabetes (P=0.048), even after controlling for age, gender, socio-economic status, blood glucose level at time of testing and verbal IQ (P=0.01). History of severe hypoglycaemia or ketoacidosis was not associated with differences in academic abilities.

CONCLUSIONS

In children and young people, Type 1 diabetes was associated with a lower verbal IQ. Moreover, increased exposure to hyperglycaemia was associated with lower spelling performance. These results imply that hyperglycaemia can affect cognitive function and/or learning processes that may affect academic achievement.

Longitudinal Evaluation of Cognitive Functioning in Young Children with Type 1 Diabetes over 18 Months

OBJECTIVES

Decrements in cognitive function may already be evident in young children with type 1 diabetes (T1D). Here we report prospectively acquired cognitive results over 18 months in a large cohort of young children with and without T1D.

METHODS

A total of 144 children with T1D (mean HbA1c: 7.9%) and 70 age-matched healthy controls (mean age both groups 8.5 years; median diabetes duration 3.9 years; mean age of onset 4.1 years) underwent neuropsychological testing at baseline and after 18-months of follow-up. We hypothesized that group differences observed at baseline would be more pronounced after 18 months, particularly in those T1D patients with greatest exposure to glycemic extremes.

RESULTS

Cognitive domain scores did not differ between groups at the 18 month testing session and did not change differently between groups over the follow-up period. However, within the T1D group, a history of diabetic ketoacidosis (DKA) was correlated with lower Verbal IQ and greater hyperglycemia exposure (HbA1c area under the curve) was inversely correlated to executive functions test performance. In addition, those with a history of both types of exposure performed most poorly on measures of executive function.

CONCLUSIONS

The subtle cognitive differences between T1D children and nondiabetic controls observed at baseline were not observed 18 months later. Within the T1D group, as at baseline, relationships between cognition (Verbal IQ and executive functions) and glycemic variables (chronic hyperglycemia and DKA history) were evident. Continued longitudinal study of this T1D cohort and their carefully matched healthy comparison group is planned.

Impact of insulin pump therapy on long-term glycemic control in a pediatric Spanish cohort

AIMS

To evaluate the efficacy and safety of Continuous Subcutaneous Insulin Infusion (CSII) in a pediatric cohort and to determine if the ISPAD/IDF/ADA criteria for good metabolic control are achieved during long periods of time.

METHODS

Retrospective longitudinal study including ninety patients [10.5 (6.5-13.9) years of age, 58% males]. Age at debut, type 1 diabetes mellitus duration, pubertal stage, HbA1c, insulin dose, mean number of glycemic controls, number of basal rates, % basal/total insulin, severe hypoglycemia and diabetic ketoacidosis events were analyzed. Subgroup analysis based on age and pubertal stage was performed.

RESULTS

HbA1c decreased from 6.9% [52 mmol/mol] to 6.7% [50 mmol/mol] after one year of CSII. Afterwards, it remained less than 7% during the follow-up period (median 3.5 ± 1.8 years (range 1-8). Prior to CSII, 76% of the subjects met ISPAD/ADA criteria. One year after initiating CSII, 96% of children had HbA1c<7.5%. Improvement in glycohemoglobin levels was most prominent in those patients with the highest HbA1c initial levels. Total insulin dose decreased from 0.89 to 0.73 UI/kg/day (p<0.001). Proportion of basal/total insulin changed significantly (47 to 42% (p<0.05)). Number of fractions of the basal rate increased from 5.6 ± 1.8 at one year of CSII to 6.7 ± 2.1 five years later. Incidence of severe hypoglycemic events decreased from 19 to 6.9 episodes/100 patient-year. Only 2 episodes of diabetic ketoacidosis occurred.

CONCLUSIONS

CSII allows reaching ISPAD/IDF/ADA goals safely during an extended follow-up period in a diabetic pediatric cohort.

Variations in Brain Volume and Growth in Young Children With Type 1 Diabetes

Early-onset type 1 diabetes may affect the developing brain during a critical window of rapid brain maturation. Structural MRI was performed on 141 children with diabetes (4-10 years of age at study entry) and 69 age-matched control subjects at two time points spaced 18 months apart. For the children with diabetes, the mean (±SD) HbA1c level was 7.9 ± 0.9% (63 ± 9.8 mmol/mol) at both time points. Relative to control subjects, children with diabetes had significantly less growth of cortical gray matter volume and cortical surface area and significantly less growth of white matter volume throughout the cortex and cerebellum. For the population with diabetes, the change in the blood glucose level at the time of scan across longitudinal time points was negatively correlated with the change in gray and white matter volumes, suggesting that fluctuating glucose levels in children with diabetes may be associated with corresponding fluctuations in brain volume. In addition, measures of hyperglycemia and glycemic variation were significantly negatively correlated with the development of surface curvature. These results demonstrate that early-onset type 1 diabetes has widespread effects on the growth of gray and white matter in children whose blood glucose levels are well within the current treatment guidelines for the management of diabetes.

[Diabetes mellitus and the central nervous system]

The review considers the current views on the central nervous system (CNS) in diabetes mellitus (DM). It discusses an attitude towards the term 'diabetic encephalopathy'. The data of investigations of cognitive functions in types 1 and 2 DM and the brain structural imaging results obtained using up-to-date technologies are considered. The results of studies of the factors that induce cerebral changes in DM and their associated cognitive impairments are given. There is evidence that hyperglycemia has a more considerable impact on the above processes than hypoglycemia; other possible factors, apart from blood glucose control, are set out. The current views on the function of insulin in the CNS and the relationship of central insulin resistance to Alzheimer's disease are outlined. There are current data on intranasal insulin application that is still exploratory, but, as might be judged from the findings, may by a promising method for the treatment and prevention of cognitive decline in both patients with DM and those without this condition.

The Impact of Diabetes on Brain Function in Childhood and Adolescence

A constant supply of glucose to the brain is critical for normal cerebral metabolism. The dysglycemia of type 1 diabetes (T1D) can affect activity, survival, and function of neural cells. Clinical studies in T1D have shown impairments in brain morphology and function. The most neurotoxic milieu seems to be young age and/or diabetic ketoacidosis at onset, severe hypoglycemia under the age of 6 years followed by chronic hyperglycemia. Adverse cognitive outcomes seem to be associated with poorer mental health outcomes. It is imperative to improve outcomes by investigating the mechanisms of injury so that neuroprotective strategies independent of glycemia can be identified.

Long-term Outcomes in Youths with Diabetes Mellitus

In this article, the author reviews the long-term outcomes and their precursors of type 1 diabetes starting in youth. The author also contrasts the changing incidence of these long-term complications as we have moved from the pre-Diabetes Control and Complications Trial (DCCT) to the post-DCCT standard of care and reviews the emerging data related to complications in youths with type 2 diabetes. Finally, the author reviews the recent understanding related to the effects of diabetes on the brain and cognition.

Predictive Low-Glucose Insulin Suspension Reduces Duration of Nocturnal Hypoglycemia in Children Without Increasing Ketosis

OBJECTIVE

Nocturnal hypoglycemia can cause seizures and is a major impediment to tight glycemic control, especially in young children with type 1 diabetes. We conducted an in-home randomized trial to assess the efficacy and safety of a continuous glucose monitor-based overnight predictive low-glucose suspend (PLGS) system.

RESEARCH DESIGN AND METHODS

In two age-groups of children with type 1 diabetes (11-14 and 4-10 years of age), a 42-night trial for each child was conducted wherein each night was assigned randomly to either having the PLGS system active (intervention night) or inactive (control night). The primary outcome was percent time <70 mg/dL overnight.

RESULTS

Median time at <70 mg/dL was reduced by 54% from 10.1% on control nights to 4.6% on intervention nights (P < 0.001) in 11-14-year-olds (n = 45) and by 50% from 6.2% to 3.1% (P < 0.001) in 4-10-year-olds (n = 36). Mean overnight glucose was lower on control versus intervention nights in both age-groups (144 ± 18 vs. 152 ± 19 mg/dL [P < 0.001] and 153 ± 14 vs. 160 ± 16 mg/dL [P = 0.004], respectively). Mean morning blood glucose was 159 ± 29 vs. 176 ± 28 mg/dL (P < 0.001) in the 11-14-year-olds and 154 ± 25 vs. 158 ± 22 mg/dL (P = 0.11) in the 4-10-year-olds, respectively. No differences were found between intervention and control in either age-group in morning blood ketosis.

CONCLUSIONS

In 4-14-year-olds, use of a nocturnal PLGS system can substantially reduce overnight hypoglycemia without an increase in morning ketosis, although overnight mean glucose is slightly higher.

The Impact of Diabetes on Cerebral Structure and Function

Diabetes alters cerebral metabolism, structure, and function. Both hyperglycemia and therapy-associated hypoglycemia are believed to have an impact on the brain, and this impact may depend on the age of the individual, their stage of neurological development, and whether they have Type 1 or Type 2 diabetes. Hypoglycemia in children with Type 1 has consistently been associated with a reduction in neurocognitive function, but such a finding has not been seen in adults with Type 1 diabetes. Both hypoglycemia and hyperglycemia have been linked with dementia in adults with Type 2 diabetes. In both Type 1 and Type 2 diabetes, recurrent episodes of treatment-associated hypoglycemia impair how well the brain can sense and respond to subsequent episodes of hypoglycemia. In this brief review, we will review how diabetes affects the brain with a focus on investigations done in our own laboratory. We have focused on using high magnetic field imaging and spectroscopy to identify subtle changes in brain structure and metabolism that may contribute to the long-term cerebral complications of diabetes. We have found evidence of microstructural changes in white matter regions, reduced gray matter density, and reduced activation of the thalamus in response to recurrent hypoglycemia in patients with Type 1 diabetes.

Longitudinal assessment of neuroanatomical and cognitive differences in young children with type 1 diabetes: association with hyperglycemia

Significant regional differences in gray and white matter volume and subtle cognitive differences between young diabetic and nondiabetic children have been observed. Here, we assessed whether these differences change over time and the relation with dysglycemia. Children ages 4 to <10 years with (n = 144) and without (n = 72) type 1 diabetes (T1D) had high-resolution structural MRI and comprehensive neurocognitive tests at baseline and 18 months and continuous glucose monitoring and HbA1c performed quarterly for 18 months. There were no differences in cognitive and executive function scores between groups at 18 months. However, children with diabetes had slower total gray and white matter growth than control subjects. Gray matter regions (left precuneus, right temporal, frontal, and parietal lobes and right medial-frontal cortex) showed lesser growth in diabetes, as did white matter areas (splenium of the corpus callosum, bilateral superior-parietal lobe, bilateral anterior forceps, and inferior-frontal fasciculus). These changes were associated with higher cumulative hyperglycemia and glucose variability but not with hypoglycemia. Young children with T1D have significant differences in total and regional gray and white matter growth in brain regions involved in complex sensorimotor processing and cognition compared with age-matched control subjects over 18 months, suggesting that chronic hyperglycemia may be detrimental to the developing brain.

Short and long term neuro-behavioral alterations in type 1 diabetes mellitus pediatric population

Type 1 diabetes mellitus (T1DM) is one of the most prevalent chronic conditions affecting individuals under the age of 18 years, with increasing incidence worldwide, especially among very young age groups, younger than 5. There is still no cure for the disease, and therapeutic goals and guidelines are a challenge. Currently, despite T1DM intensive management and technological interventions in therapy, the majority of pediatric patients do not achieve glycemic control goals. This leads to a potential prognosis of long term diabetic complications, nephrological, cardiac, ophthalmological and neurological. Unfortunately, the neurological manifestations, including neurocognitive and behavioral complications, may present soon after disease onset, during childhood and adolescence. These manifestations may be prominent, but at times subtle, thus they are often not reported by patients or physicians as related to the diabetes. Furthermore, the metabolic mechanism for such manifestations has been inconsistent and difficult to interpret in practical clinical care, as reported in several reviews on the topic of brain and T1DM. However, new technological methods for brain assessment, as well as the introduction of continuous glucose monitoring, provide new insights and information regarding brain related manifestations and glycemic variability and control parameters, which may impact the clinical care of children and youth with T1DM. This paper provides a comprehensive review of the most recently reported behavioral, cognitive domains, sleep related, electrophysiological, and structural alterations in children and adolescences from a novel point of view. The review focuses on reported impairments based on duration of T1DM, its timeline, and modifiable disease related risk parameters. These findings are not without controversy, and limitations of data are presented in addition to recommendations for future research direction.

The interface of child mental health and juvenile diabetes mellitus

Diabetes mellitus is a common childhood illness, and its management is often complicated by mental health challenges. Psychiatric comorbidities are common, including anxiety, depression, and eating disorders. The illness can profoundly affect the developing brain and family functioning and have lifelong consequences. The child mental health provider can provide valuable assistance to support the child and family and assessment and treatment of comorbid mental health problems and to promote positive family functioning and normal developmental progress.

Risk factors for decline in IQ in youth with type 1 diabetes over the 12 years from diagnosis/illness onset

OBJECTIVE

This study examined illness-related change in intelligence quotient (IQ) in a cohort of youth with type 1 diabetes studied prospectively from disease onset in childhood to follow-up 12 years later in late adolescence/early adulthood.

RESEARCH DESIGN AND METHODS

Participants included type 1 diabetes patients (n = 95; mean age at follow-up 21.3 years) and healthy control participants (HCs; n = 67; mean age at follow-up 21.0 years) from a cohort followed prospectively. Measures included Wechsler Preschool and Primary Scale of Intelligence-Revised, Wechsler Intelligence Scale for Children-Revised, and Wechsler Abbreviated Scale of Intelligence and prospective collection of data on metabolic control history.

RESULTS

Young people with type 1 diabetes showed greater decline in verbal IQ (VIQ) and full-scale IQ (FSIQ), but not performance IQ (PIQ), than HCs. Within the diabetes group, a younger age at diabetes onset was associated with a decline in PIQ and FSIQ (P ≤ 0.001). A history of hypoglycemic seizures was associated with a decline in VIQ (P = 0.002). Long-term metabolic control was not associated with changes in IQ. Interaction terms were not significant, suggesting no moderating effect of one diabetes-related variable over another.

CONCLUSIONS

The presence of diabetes may negatively influence some aspects of IQ over time. Specific illness risk factors, such as an earlier age of disease onset and a history of hypoglycemic seizures, appear to put the young person at greater risk. Academic progress of children identified as at risk should be monitored and educational supports provided if necessary.

Prolonged exposure to high and variable phenylalanine levels over the lifetime predicts brain white matter integrity in children with phenylketonuria

In this study, we retrospectively examined the microstructural white matter integrity of children with early- and continuously-treated PKU (N=36) in relation to multiple indices of phenylalanine (Phe) control over the lifetime. White matter integrity was assessed using mean diffusivity (MD) from diffusion tensor imaging (DTI). Eight lifetime indices of Phe control were computed to reflect average Phe (mean, index of dietary control), variability in Phe (standard deviation, standard error of estimate, % spikes), change in Phe with age (slope), and prolonged exposure to Phe (mean exposure, standard deviation exposure). Of these indices, mean Phe, mean exposure, and standard deviation exposure were the most powerful predictors of widespread microstructural white matter integrity compromise. Findings from the two previously unexamined exposure indices reflected the accumulative effects of elevations and variability in Phe. Given that prolonged exposure to elevated and variable Phe was particularly detrimental to white matter integrity, Phe should be carefully monitored and controlled throughout childhood, without liberalization of Phe control as children with PKU age.

Type 1 diabetes-associated cognitive decline: a meta-analysis and update of the current literature

BACKGROUND

Type 1 diabetes (T1D) can have a significant impact on brain structure and function, which is referred to as T1D-associated cognitive decline (T1DACD). Diabetes duration, early onset disease, and diabetes-associated complications are all proposed as factors contributing to T1DACD. However, there have been no comparisons in T1DACD between children and adults with T1D. To obtain a better insight into the occurrence and effects of T1DACD in T1D, the aim of the present meta-analysis was to investigate differences between children and adults and to analyse factors contributing T1DACD.

METHODS

Two electronic databases were consulted: PubMed and ISI Web of Knowledge. Literature published up until the end of 2013 was included in the analysis. Effect sizes (Cohen's d), which are standardized differences between experimental and control groups, were calculated.

RESULTS

There was a small to modest decrease in cognitive performance in T1D patients compared with non-diabetic controls. Children with T1D performed worse while testing for executive function, full intelligence quotient (IQ), and motor speed, whereas adults with T1D performed worse while testing the full, verbal and performance IQ, part of the executive function, memory, spatial memory, and motor speed. Episodes of severe hypoglycemia, chronic hyperglycemia, and age of onset can be significant factors influencing cognitive function in T1D.

CONCLUSIONS

The findings in the literature suggest that T1DACD is more severe in adults than children, indicating that age and diabetes duration contribute to this T1DACD.

Brain structural changes and their correlation with vascular disease in type 2 diabetes mellitus patients: a voxel-based morphometric study

Voxel-based morphometry has been used in the study of alterations in brain structure in type 1 diabetes mellitus patients. These changes are associated with clinical indices. The age at onset, pathogenesis, and treatment of type 1 diabetes mellitus are different from those for type 2 diabetes mellitus. Thus, type 1 and type 2 diabetes mellitus may have different impacts on brain structure. Only a few studies of the alterations in brain structure in type 2 diabetes mellitus patients using voxel-based morphometry have been conducted, with inconsistent results. We detected subtle changes in the brain structure of 23 cases of type 2 diabetes mellitus, and demonstrated that there was no significant difference between the total volume of gray and white matter of the brain of type 2 diabetes mellitus patients and that in controls. Regional atrophy of gray matter mainly occurred in the right temporal and left occipital cortex, while regional atrophy of white matter involved the right temporal lobe and the right cerebellar hemisphere. The ankle-brachial index in patients with type 2 diabetes mellitus strongly correlated with the volume of brain regions in the default mode network. The ankle-brachial index, followed by the level of glycosylated hemoglobin, most strongly correlated with the volume of gray matter in the right temporal lobe. These data suggest that voxel-based morphometry could detect small structural changes in patients with type 2 diabetes mellitus. Early macrovascular atherosclerosis may play a crucial role in subtle brain atrophy in type 2 diabetes mellitus patients, with chronic hyperglycemia playing a lesser role.

Neurocognitive outcomes in pediatric diabetes: a developmental perspective

The impact of diabetes on the developing brain is well-accepted. Effects on neurocognitive functioning are moderate but have larger functional implications, especially when considered through a developmental lens. Pathophysiological factors such as severe hypoglycemia and chronic hyperglycemia can alter developmental trajectories in early childhood and perhaps at later periods. In this paper, we selectively review neurocognitive outcomes in pediatric diabetes (largely type 1), integrating recent research from developmental neuroscience and neuroimaging. We examine the effects of diabetes at different stages and place findings within a neurodevelopmental diathesis/stress framework. Early-onset diabetes is associated with specific effects on memory and more global cognitive late-effects, but less is known about cognitive outcomes of diabetes in later childhood and in adolescence, a time of increased neurobehavioral vulnerability that has received relatively limited empirical attention. Studies are also needed to better elucidate risk and protective factors that may moderate neurodevelopmental outcomes in youth with diabetes.

Task-induced brain activity patterns in type 2 diabetes: a potential biomarker for cognitive decline

Patients with type 2 diabetes demonstrate reduced functional connectivity within the resting state default mode network (DMN), which may signal heightened risk for cognitive decline. In other populations at risk for cognitive decline, additional magnetic resonance imaging abnormalities are evident during task performance, including impaired deactivation of the DMN and reduced activation of task-relevant regions. We investigated whether middle-aged type 2 diabetic patients show these brain activity patterns during encoding and recognition tasks. Compared with control participants, we observed both reduced 1) activation of the dorsolateral prefrontal cortex during encoding and 2) deactivation of the DMN during recognition in type 2 diabetic patients, despite normal cognition. During recognition, activation in several task-relevant regions, including the dorsolateral prefrontal cortex and DMN regions, was positively correlated with HbA1c and insulin resistance, suggesting that these important markers of glucose metabolism impact the brain's response to a cognitive challenge. Plasma glucose ≥11 mmol/L was associated with impaired deactivation of the DMN, suggesting that acute hyperglycemia contributes to brain abnormalities. Since elderly type 2 diabetic patients often demonstrate cognitive impairments, it is possible that these task-induced brain activity patterns observed in middle age may signal impending cognitive decline.

Neurocognitive functioning in children and adolescents at the time of type 1 diabetes diagnosis: associations with glycemic control 1 year after diagnosis

OBJECTIVE

To determine whether impairments in neurocognitive functioning are detectable at type 1 diabetes diagnosis and associated with subsequent glycemic control.

RESEARCH DESIGN AND METHODS

Children/adolescents (N = 147) aged 5-18 years completed neuropsychological testing during their inpatient hospitalization for new-onset type 1 diabetes. Test scores were compared with normative data using one-sample Student t tests. Children with onset before 8 years of age were compared with children aged 9-18 years using ANOVA, and associations between neurocognitive performance at diagnosis and glycemic control 1 year postdiagnosis were examined using regression analyses.

RESULTS

Children with type 1 diabetes performed significantly below expectations on most neurocognitive measures (P values <0.0001), with large decrements from the normative mean evident in psychomotor speed (>1 SD), visuomotor integration (0.7 SD), and phonemic fluency (0.8 SD). High incidence of impairment (scores less than second percentile) was evident on all tasks except digit span. Dominant-hand psychomotor speed was significantly associated with poor glycemic control (A1C ≥9.5% [80 mmol/mol]; P = 0.032) 1 year postdiagnosis, controlling for race/ethnicity, sex, and reading ability. Impaired psychomotor speed was associated with a 0.77% increase in mean A1C (8.4 mmol/mol).

CONCLUSIONS

Deficits were evident in neurocognitive functioning within days of diabetes diagnosis that were associated with diabetes outcomes over 1 year postdiagnosis. Impairment was most apparent in psychomotor speed, consistent with research implicating damage to posterior white matter tracts and associated gray matter regions in type 1 diabetes. Psychomotor impairment may be an early marker for a broader neurobehavioral vulnerability that has implications for long-term diabetes management.

Ghrelin inhibits high glucose-induced PC12 cell apoptosis by regulating TLR4/NF-κB pathway

Ghrelin has a protective effect on diabetic encephalopathy. To expound the protective mechanism, we investigated the effects of ghrelin on high glucose-induced cell apoptosis and intracellular signaling in cultured PC12, which is a suitable model for studying neuronal cell death. High glucose-induced PC12 apoptosis was significantly inhibited by co-treatment of ghrelin. Sustaining inflammatory response is one of the molecular mechanisms of diabetic encephalopathy and TLR4 signaling has close relationship with inflammatory response. But there is no report about the biologic role of toll-like receptor 4/nuclear factor-κB (TLR4/NF-κB) signaling in controlling high glucose-induced PC12 apoptosis by ghrelin. In this study, we found that TLR4/NF-κB pathway was activated by high glucose stimulation in PC12 and significantly alleviated by the co-treatment of ghrelin. From these findings, we made the conclusion that ghrelin could attenuate the symptoms of diabetic encephalopathy, which alleviates inflammatory reaction of diabetic encephalopathy by regulating TLR4/NF-κB pathway.

Cognitive functioning in young children with type 1 diabetes

The aim of this study was to assess cognitive functioning in children with type 1 diabetes (T1D) and examine whether glycemic history influences cognitive function. Neuropsychological evaluation of 216 children (healthy controls, n = 72; T1D, n = 144) ages 4-10 years across five DirecNet sites. Cognitive domains included IQ, Executive Functions, Learning and Memory, and Processing Speed. Behavioral, mood, parental IQ data, and T1D glycemic history since diagnosis were collected. The cohorts did not differ in age, gender or parent IQ. Median T1D duration was 2.5 years and average onset age was 4 years. After covarying age, gender, and parental IQ, the IQ and the Executive Functions domain scores trended lower (both p = .02, not statistically significant adjusting for multiple comparisons) with T1D relative to controls. Children with T1D were rated by parents as having more depressive and somatic symptoms (p < .001). Learning and memory (p = .46) and processing speed (p = .25) were similar. Trends in the data supported that the degree of hyperglycemia was associated with Executive Functions, and to a lesser extent, Child IQ and Learning and Memory. Differences in cognition are subtle in young children with T1D within 2 years of onset. Longitudinal evaluations will help determine whether these findings change or become more pronounced with time.

Neuroanatomical correlates of dysglycemia in young children with type 1 diabetes

Studies of brain structure in type 1 diabetes (T1D) describe widespread neuroanatomical differences related to exposure to glycemic dysregulation in adults and adolescents. In this study, we investigate the neuroanatomical correlates of dysglycemia in very young children with early-onset T1D. Structural magnetic resonance images of the brain were acquired in 142 children with T1D and 68 age-matched control subjects (mean age 7.0 ± 1.7 years) on six identical scanners. Whole-brain volumetric analyses were conducted using voxel-based morphometry to detect regional differences between groups and to investigate correlations between regional brain volumes and measures of glycemic exposure (including data from continuous glucose monitoring). Relative to control subjects, the T1D group displayed decreased gray matter volume (GMV) in bilateral occipital and cerebellar regions (P < 0.001) and increased GMV in the left inferior prefrontal, insula, and temporal pole regions (P = 0.002). Within the T1D group, hyperglycemic exposure was associated with decreased GMV in medial frontal and temporal-occipital regions and increased GMV in lateral prefrontal regions. Cognitive correlations of intelligence quotient to GMV were found in cerebellar-occipital regions and medial prefrontal cortex for control subjects, as expected, but not for the T1D group. Thus, early-onset T1D affects regions of the brain that are associated with typical cognitive development.

Glycemic extremes in youth with T1DM: the structural and functional integrity of the developing brain

The adult brain accounts for a disproportionally large percentage of the body’s total energy consumption (1). However, during brain development,energy demand is even higher, reaching the adult rate by age 2 and increasing to nearly twice the adult rate by age 10, followed by gradual reduction toward adult levels in the next decade (1,2). The dramatic changes in brain metabolism occurring over the first two decades of life coincide with the initial proliferation and then pruning of synapses to adult levels.The brain derives its energy almost exclusively from glucose and is largely driven by neuronal signaling, biosynthesis, and neuroprotection (3–6).Glucose homeostasis in the body is tightly regulated by a series of hormones and physiologic responses. As a result, hypoglycemia and hyperglycemia are rare occurrences in normal individuals, but they occur commonly inpatients with type 1 diabetes mellitus (T1DM) due to a dysfunction of peripheral glucose-insulin-glucagon responses and non-physiologic doses of exogenous insulin, which imperfectly mimic normal physiology. These extremes can occur more frequently in children and adolescents with T1DM due to the inadequacies of insulin replacement therapy, events leading to the diagnosis [prolonged untreated hyperglycemia and diabetic ketoacidosis (DKA)], and to behavioral factors interfering with optimal treatment. When faced with fluctuations in glucose supply the metabolism of the body and brain change dramatically, largely to conserve resources and, at a cost to other organs, to preserve brain function (7). However,if the normal physiological mechanisms that prevent these severe glucose fluctuations and maintain homeostasis are impaired, neuronal function and potentially viability can be affected (8–11).

Network-level structural abnormalities of cerebral cortex in type 1 diabetes mellitus

Type 1 diabetes mellitus (T1DM) usually begins in childhood and adolescence and causes lifelong damage to several major organs including the brain. Despite increasing evidence of T1DM-induced structural deficits in cortical regions implicated in higher cognitive and emotional functions, little is known whether and how the structural connectivity between these regions is altered in the T1DM brain. Using inter-regional covariance of cortical thickness measurements from high-resolution T1-weighted magnetic resonance data, we examined the topological organizations of cortical structural networks in 81 T1DM patients and 38 healthy subjects. We found a relative absence of hierarchically high-level hubs in the prefrontal lobe of T1DM patients, which suggests ineffective top-down control of the prefrontal cortex in T1DM. Furthermore, inter-network connections between the strategic/executive control system and systems subserving other cortical functions including language and mnemonic/emotional processing were also less integrated in T1DM patients than in healthy individuals. The current results provide structural evidence for T1DM-related dysfunctional cortical organization, which specifically underlie the top-down cognitive control of language, memory, and emotion.

Defective counterregulation and hypoglycemia unawareness in diabetes: mechanisms and emerging treatments

For people with diabetes, hypoglycemia remains the limiting factor in achieving glycemic control. This article reviews recent advances in how the brain senses and responds to hypoglycemia. Novel mechanisms by which individuals with insulin-treated diabetes develop hypoglycemia unawareness and impaired counterregulatory responses are outlined. Prevention strategies for reducing the incidence of hypoglycemia are discussed.

White matter microstructural integrity in youth with type 1 diabetes

Decreased white and gray matter volumes have been reported in youth with type 1 diabetes mellitus (T1DM), but the effects of hyperglycemia on white matter integrity have not been quantitatively assessed during brain development. We performed diffusion tensor imaging, using two complimentary approaches--region-of-interest and voxelwise tract-based spatial statistics--to quantify white matter integrity in a large retrospective study of T1DM youth and control participants. Exposure to chronic hyperglycemia, severe hyperglycemic episodes, and severe hypoglycemia, as defined in the Diabetes Control and Complications Trial (DCCT), were estimated through medical records review, HbA(1c) levels, and interview of parents and youth. We found lower fractional anisotropy in the superior parietal lobule and reduced mean diffusivity in the thalamus in the T1DM group. A history of three or more severe hyperglycemic episodes was associated with reduced anisotropy and increased diffusivity in the superior parietal lobule and increased diffusivity in the hippocampus. These results add microstructural integrity of white matter to the range of structural brain alterations seen in T1DM youth and suggest vulnerability of the superior parietal lobule, hippocampus, and thalamus to glycemic extremes during brain development. Longitudinal analyses will be necessary to determine how these alterations change with age or additional glycemic exposure.

White matter structural differences in young children with type 1 diabetes: a diffusion tensor imaging study

OBJECTIVE

To detect clinical correlates of cognitive abilities and white matter (WM) microstructural changes using diffusion tensor imaging (DTI) in young children with type 1 diabetes.

RESEARCH DESIGN AND METHODS

Children, ages 3 to <10 years, with type 1 diabetes (n = 22) and age- and sex-matched healthy control subjects (n = 14) completed neurocognitive testing and DTI scans.

RESULTS

Compared with healthy controls, children with type 1 diabetes had lower axial diffusivity (AD) values (P = 0.046) in the temporal and parietal lobe regions. There were no significant differences between groups in fractional anisotropy and radial diffusivity (RD). Within the diabetes group, there was a significant, positive correlation between time-weighted HbA(1c) and RD (P = 0.028). A higher, time-weighted HbA(1c) value was significantly correlated with lower overall intellectual functioning measured by the full-scale intelligence quotient (P = 0.03).

CONCLUSIONS

Children with type 1 diabetes had significantly different WM structure (as measured by AD) when compared with controls. In addition, WM structural differences (as measured by RD) were significantly correlated with their HbA(1c) values. Additional studies are needed to determine if WM microstructural differences in young children with type 1 diabetes predict future neurocognitive outcome.

Early brain vulnerability in Wolfram syndrome

Wolfram Syndrome (WFS) is a rare autosomal recessive disease characterized by insulin-dependent diabetes mellitus, optic nerve atrophy, diabetes insipidus, deafness, and neurological dysfunction leading to death in mid-adulthood. WFS is caused by mutations in the WFS1 gene, which lead to endoplasmic reticulum (ER) stress-mediated cell death. Case studies have found widespread brain atrophy in late stage WFS. However, it is not known when in the disease course these brain abnormalities arise, and whether there is differential vulnerability across brain regions and tissue classes. To address this limitation, we quantified regional brain abnormalities across multiple imaging modalities in a cohort of young patients in relatively early stages of WFS. Children and young adults with WFS were evaluated with neurological, cognitive and structural magnetic resonance imaging measures. Compared to normative data, the WFS group had intact cognition, significant anxiety and depression, and gait abnormalities. Compared to healthy and type 1 diabetic control groups, the WFS group had smaller intracranial volume and preferentially affected gray matter volume and white matter microstructural integrity in the brainstem, cerebellum and optic radiations. Abnormalities were detected in even the youngest patients with mildest symptoms, and some measures did not follow the typical age-dependent developmental trajectory. These results establish that WFS is associated with smaller intracranial volume with specific abnormalities in the brainstem and cerebellum, even at the earliest stage of clinical symptoms. This pattern of abnormalities suggests that WFS has a pronounced impact on early brain development in addition to later neurodegenerative effects, representing a significant new insight into the WFS disease process. Longitudinal studies will be critical for confirming and expanding our understanding of the impact of ER stress dysregulation on brain development.

Resting-state brain networks in type 1 diabetic patients with and without microangiopathy and their relation to cognitive functions and disease variables

Cognitive functioning depends on intact brain networks that can be assessed with functional magnetic resonance imaging (fMRI) techniques. We hypothesized that cognitive decrements in type 1 diabetes mellitus (T1DM) are associated with alterations in resting-state neural connectivity and that these changes vary according to the degree of microangiopathy. T1DM patients with (MA(+): n = 49) and without (MA(-): n = 52) microangiopathy were compared with 48 healthy control subjects. All completed a neuropsychological assessment and resting-state fMRI. Networks were identified using multisubject independent component analysis; specific group differences within each network were analyzed using the dual-regression method, corrected for confounding factors and multiple comparisons. Relative to control subjects, MA(-) patients showed increased connectivity in networks involved in motor and visual processes, whereas MA(+) patients showed decreased connectivity in networks involving attention, working memory, auditory and language processing, and motor and visual processes. Better information-processing speed and general cognitive ability were related to increased degree of connectivity. T1DM is associated with a functional reorganization of neural networks that varies, dependent on the presence or absence of microangiopathy.

Academic skills in children with early-onset type 1 diabetes: the effects of diabetes-related risk factors

AIM

The study aimed to assess the effects of diabetes-related risk factors, especially severe hypoglycaemia,on the academic skills of children with early-onset type 1 diabetes mellitus (T1DM).

METHOD

The study comprised 63 children with T1DM (31 females, 32 males; mean age 9 y 11 mo,SD 4 mo) and 92 comparison children without diabetes (40 females, 52 males;mean age 9 y 9 mo,SD 3 mo). Children were included if T1DM had been diagnosed before the age of 5 years and if they were aged between 9 and 10 years at the time of study. Children were not included if their native language was not Finnish and if they had a diagnosed neurological disorder that affected their cognitive development. Among the T1DM group, 37 had and 26 had not experienced severe hypoglycaemia and 26 had avoided severe hypoglycaemia. Severe hypoglycaemia, diabetic ketoacidosis(DKA), and glycaemic control were used as T1DM-related factors. Task performance in reading, spelling, and mathematics was compared among the three groups, and the effects of the T1DM-related factors were analysed with general linear models.

RESULTS

The groups with (p<0.001) and without (p=0.001) severe hypoglycaemia demonstrated a poorer performance than the comparison group in spelling, and the group without severe hypoglycaemia showed a poorer performance than the comparison group in mathematics (p=0.003).Severe hypoglycaemia, DKA, and recent glycaemic control were not associated with poorer skills,but poorer first-year glycaemic control was associated with poorer spelling (p=0.013).

INTERPRETATION

An early onset of T1DM can increase the risk of learning problems, independently of the history of severe hypoglycaemia or DKA. Poorer glycaemic control after the first year of T1DM is associated with a poorer acquisition of academic skills indicating the effect of the timing of metabolic aberrations on cognitive development.

Role of angiotensin II in the brain inflammatory events during experimental diabetes in rats

Hyperglycemia during diabetes is one of the causes of encephalopathy. However, diabetes causes chronic inflammatory complications and among them is peripheral neuropathy. Since, diabetes is one of the major risk factors for cerebrovascular disease, inflammatory process could take place in central nervous system (CNS). To test that hypothesis, experiments to determine inflammatory events in CNS during streptozotocin-induced diabetes were performed. Diabetes was induced by intravenous injection of streptozotocin (STZ). Brain angiotensin II (Ang II), monocyte/macrophage (ED-1 positive cells), CD8, the intercellular adhesion molecule-1 (ICAM-1), the lymphocyte function-associated antigen-1 (LFA-1) and superoxide anion were determined by hystochemical and immunohistochemical methods. Nitric oxide (NO), malondialdehyde (MDA) and catalase activity were measured in brain homogenates by enzymatic and biochemical methods. This research showed increased expressions of Ang II, ICAM-1, LFA-1 and CD8 positive cells in diverse zones of cerebrum and cerebellum of diabetic rats (week 8). Treatment of diabetic animals with losartan or enalapril reduced the expression of those molecules. Values of lipid peroxidation, nitrite content and superoxide anion expression remained similar to control rats. Only decreased activity of catalase was observed in diabetic animals, but losartan or enalapril failed to modify catalase activity. This study suggests the presence of Ang II-mediated brain inflammatory events in diabetes probably mediated by AT1 receptors.

Age-related loss of brain volume and T2 relaxation time in youth with type 1 diabetes

OBJECTIVE

2 Childhood-onset type 1 diabetes is associated with neurocognitive deficits, but there is limited evidence to date regarding associated neuroanatomical brain changes and their relationship to illness variables such as age at disease onset. This report examines age-related changes in volume and T2 relaxation time (a fundamental parameter of magnetic resonance imaging that reflects tissue health) across the whole brain.

RESEARCH DESIGN AND METHODS

Type 1 diabetes, N = 79 (mean age 20.32 ± 4.24 years), and healthy control participants, N = 50 (mean age 20.53 ± 3.60 years). There were no substantial group differences on socioeconomic status, sex ratio, or intelligence quotient.

RESULTS

Regression analyses revealed a negative correlation between age and brain changes, with decreasing gray matter volume and T2 relaxation time with age in multiple brain regions in the type 1 diabetes group. In comparison, the age-related decline in the control group was small. Examination of the interaction of group and age confirmed a group difference (type 1 diabetes vs. control) in the relationship between age and brain volume/T2 relaxation time.

CONCLUSIONS

We demonstrated an interaction between age and group in predicting brain volumes and T2 relaxation time such that there was a decline in these outcomes in type 1 diabetic participants that was much less evident in control subjects. Findings suggest the neurodevelopmental pathways of youth with type 1 diabetes have diverged from those of their healthy peers by late adolescence and early adulthood but the explanation for this phenomenon remains to be clarified.

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.

The effect of recurrent severe hypoglycemia on cognitive performance in children with type 1 diabetes: a meta-analysis

The purpose of this study was to investigate the existence and extent of cognitive impairment in type 1 diabetic children with episodes of recurrent severe hypoglycemia, using meta-analysis to synthesize data across studies. The meta-analysis sample included: 441 children with diabetes and recurrent severe hypoglycemia, 560 children with diabetes and without recurrent severe hypoglycemia. Overall, children with type 1 diabetes and recurrent severe hypoglycemia had slightly lower performance than diabetic children without severe hypoglycemia, only in some cognitive domains: intelligence, memory, learning, and verbal fluency/language. Greater impairment was found in memory and learning. No impairment was found for motor speed. Our results seem to confirm the hypothesis that recurrent severe hypoglycemia has a selective negative effect on the children's cognitive functions. However, these results must be considered with caution taking into account factors such as small sample sizes, the different definitions of severe hypoglycemia, and the variety of neuropsychological tests used.

Continuous blood glucose monitoring in diabetes treatment

Continuous glucose monitoring system (CGMS) is a developing technology in the field of diabetes treatment since it enables patients to effectively control and adjust their insulin therapy. Clinical trials have shown its efficacy in lowering HbAlc significantly especially in adults with type 1 diabetes and those with HbAlc >8%. Improvement is sustained for at least one year. Conflicting data exist for children. Most recent studies agree that the nearly daily use of CGMS is accompanied by significant lowering of HbA1c independent of age. However, the randomized clinical trials have shown that the use of CGMS does not reduce significantly the number of severe hypoglycemic episodes as it is expected, but recent data indicate that it reduces the time spent in hypoglycemia. Accuracy remains a key issue for CGMS, particularly in children and adolescents who may have increased variability of blood glucose. CGMS cost is another barrier to the everyday use since reimbursement of CGM is limited to a few countries only. This review will focus on the present status of the use of CGMS in type 1 diabetes (T1D) patients.