Hypoglycaemia in childhood onset type 1 diabetes--part villain, but not the only one

COGNITIVE FUNCTIONS IN CHILDREN WITH TYPE I DIABETES

OBJECTIVE

The aim: To assess the patterns and severity of cognitive impairment in children with type 1 diabetes as well as its association with disease onset and poor glycemic control.

PATIENTS AND METHODS

Materials and methods: We assessed higher mental function and screened for psychosocial functioning in 60 children with type 1 DM and 60 age-matched control using the Modified Mini-Mental State examination and Pediatric Symptoms Checklist and its relation with age, gender, socioeconomic status, age at the onset of disease, duration of disease, HbA1c level, frequency of diabetic ketoacidosis and hypoglycemic attacks and type of treatment.

RESULTS

Results: Diabetic patients demonstrated a lower Modified Mini-Mental State examination score than controls (25.12±4.58 versus 30.08±2.95) with a highly significant difference. Furthermore, the mean Pediatric symptoms checklist score in patients was 39.08±8.18 which was much lower than that of controls 54.42±6.0 with a highly significant difference.

CONCLUSION

Conclusions: There is neurocognitive impairment in diabetic children compared to non-diabetics, and poor glycemic control whether hyper or hypoglycemia could affect their cognition and mental health.

Impact of glucose metabolism on the developing brain

Glucose is the most important substrate for proper brain functioning and development, with an increased glucose consumption in relation to the need of creating new brain structures and connections. Therefore, alterations in glucose homeostasis will inevitably be associated with changes in the development of the Nervous System. Several studies demonstrated how the alteration of glucose homeostasis - both hyper and hypoglycemia- may interfere with the development of brain structures and cognitivity, including deficits in intelligence quotient, anomalies in learning and memory, as well as differences in the executive functions. Importantly, differences in brain structure and functionality were found after a single episode of diabetic ketoacidosis suggesting the importance of glycemic control and stressing the need of screening programs for type 1 diabetes to protect children from this dramatic condition. The exciting progresses of the neuroimaging techniques such as diffusion tensor imaging, has helped to improve the understanding of the effects, outcomes and mechanisms underlying brain changes following dysglycemia, and will lead to more insights on the physio-pathological mechanisms and related neurological consequences about hyper and hypoglycemia.

The effect of type 1 diabetes on the developing brain

The effect of type 1 diabetes on the developing brain is a topic of primary research interest. A variety of potential dysglycaemic insults to the brain can cause cellular and structural injury and lead to altered neuropsychological outcomes. These outcomes might be subtle in terms of cognition but appear to persist into adult life. Age and circumstance at diagnosis appear to play a substantial role in potential CNS injury. A history of diabetic ketoacidosis and chronic hyperglycaemia appear to be more injurious than previously suspected, whereas a history of severe hypoglycaemia is perhaps less injurious. Neurocognitive deficits manifest across multiple cognitive domains, including executive function and speed of information processing. Some evidence suggests that subtle brain injury might directly contribute to psychological and mental health outcomes. Impaired executive function and mental health, in turn, could affect patients' adherence and the ability to make adaptive lifestyle choices. Impaired executive functioning creates a potential feedback loop of diabetic dysglycaemia leading to brain injury, further impaired executive function and mental health, which results in suboptimal adherence, and further dysglycaemia. Clinicians dealing with patients with suboptimal glycaemic outcomes should be aware of these potential issues.

Hemoglobin A1c Variability Predicts Symptoms of Depression in Elderly Individuals With Type 2 Diabetes

OBJECTIVE

This study aimed to analyze the relationship of variability in hemoglobin A_1c (HbA_1c) over years with subsequent depressive symptoms.

RESEARCH DESIGN AND METHODS

Subjects (n = 837) were participants of the Israel Diabetes and Cognitive Decline (IDCD) study, which aimed to examine the relationship of characteristics of long-term type 2 diabetes with cognitive decline. All pertain to a diabetes registry established in 1998, which contains an average of 18 HbA_1c measurements per subject. The results presented here are based on the IDCD baseline examination. Symptoms of depression were assessed using the 15-item version of the Geriatric Depression Scale (GDS). To quantify the association between variability in glycemic control (measured as the SD of HbA_1c measurements [HbA_1c-SD]) since 1998 with the number of depression symptoms at IDCD baseline, incidence rate ratios (IRRs) and corresponding 95% CIs were estimated via negative binomial regression modeling and used to account for the overdispersion in GDS scores.

RESULTS

Subjects' ages averaged 72.74 years (SD 4.63 years), and the mean number of years in the diabetes registry was 8.7 (SD 2.64 years). The mean GDS score was 2.16 (SD 2.26); 10% of subjects had a GDS score ≥6, the cutoff for clinically significant depression. Mean HbA_1c significantly correlated with HbA_1c-SD (r = 0.6625; P < 0.0001). The SD, but not the mean, of HbA_1c measurements was significantly associated with the number of subsequent depressive symptoms. For each additional 1% increase in HbA_1c-SD, the number of depressive symptoms increased by a factor of 1.31 (IRR = 1.31 [95% CI 1.03-1.67]; P = 0.03).

CONCLUSIONS

Variability in glycemic control is associated with more depressive symptoms.

Statin Use and Cognitive Impairment in Patients With Type 1 Diabetes: An Observational Study

OBJECTIVE

We aimed to assess a wide range of cognitive functions in patients with type 1 diabetes (DM1) compared with healthy control subjects and to evaluate the effects of statins on cognitive functions in DM1 patients.

MATERIALS AND METHODS

The sample studied consisted of 55 DM1 patients (80.0% with hyperlipidemia, 20% with statin treatment) and 36 age-matched control subjects (77.8% with hyperlipidemia) without diabetes or statin use. Their cognitive functions (attention, memory, and executive functions) were evaluated with the trail making test, controlled oral word association test (COWAT), Rey-Osterrieth complex figure test, brain damage test (diagnosticum für cerebralschädigung, DCS), Wisconsin card sorting test (WCST), and digit span and block design tests from the revised Wechsler adult intelligence scale.

RESULTS

Cognitive performance was impaired in DM1 patients when compared with the control group with regard to semantic verbal fluency (COWAT_animals), visual learning (DCS), conceptual-level responses, executive functions (WCST random errors), and WCST trials to complete the first category. Subgroups of DM1 patients distinguished on the basis of statin therapy did not differ with regard to verbal fluency (COWAT_animals), visual learning (DCS), conceptual-level responses, executive functions (WCST random errors), and WCST trials to complete the first category. Multivariate analysis also does not show the impact of statin therapy on cognitive functioning regardless of the duration of education, microangiopathic evidence, the presence of hyperlipidemia, or antihypertensive therapy.

CONCLUSIONS

We find impairment of cognitive functions in DM1 patients when compared with control subjects without diabetes. However, we show neither the effect of statins nor the significant influence of metabolic control, microangiopathic complications, or the presence of hyperlipidemia on cognitive functions in DM1 patients.

Relationships of DTI findings with neurocognitive dysfunction in children with Type 1 diabetes mellitus

OBJECTIVE

To determine whether there were diffusion tensor imaging (DTI) changes in the brain among children with Type 1 diabetes mellitus (DM) and investigate the correlation between the fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values and neurocognitive functions.

METHODS

35 children with Type 1 DM and 21 age-matched healthy control subjects were included. Neurocognitive functions of subjects with Type 1 DM were evaluated. In both groups, FA and ADC values were calculated in 20 different locations. The association between neurocognitive function tests and FA and ADC values was investigated.

RESULTS

Subjects with diabetes had significant changes in FA and ADC values in widespread brain regions compared with the healthy control group. ADC values in the caudate nucleus were negatively associated with verbal point. Increased ADC values in the genu of the corpus callosum were positively associated with Stroop test. There was a negative correlation between the ADC values of the parietal white matter and the judgment of line orientation test. FA values of the inferior longitudinal fasciculus were positively correlated with performance point. However, a negative correlation was noted between FA values of mid-brain and intelligence quotient level as well as another negative correlation between FA values of the posterior crus of the internal capsule and thalamus with verbal point.

CONCLUSION

Subjects with diabetes demonstrated significant changes in FA and ADC values in widespread brain regions, and such changes could be early features of injury to myelinated fibres or axonal degeneration. Our findings suggest that brain damage may have begun at the cellular level in the initial stage of Type 1 diabetes and neurocognitive impairments may be inevitable.

ADVANCES IN KNOWLEDGE

DTI can demonstrate ADC and FA changes which are well correlated with neurocognitive dysfunction in the brains of children with Type 1 DM. This may help us in guiding preventive measures in early period of the disease before deterioration of neurocognitive functions.

Brain Activation and Psychomotor Speed in Middle-Aged Patients with Type 1 Diabetes: Relationships with Hyperglycemia and Brain Small Vessel Disease

Slower psychomotor speed is very common in patients with type 1 diabetes mellitus (T1D), but the underlying mechanisms are not clear. We propose that hyperglycemia is associated with slower psychomotor speed via disruption of brain activation. Eighty-five adults (48% women, mean age: 49.0 years, mean duration: 40.8) with childhood onset T1D were recruited for this cross-sectional study. Median response time in seconds (longer = worse performance) and brain activation were measured while performing a psychomotor speed task. Exposure to hyperglycemia, measured as glycosylated hemoglobin A1c, was associated with longer response time and with higher activation in the inferior frontal gyrus and primary sensorimotor and dorsal cingulate cortex. Higher activation in inferior frontal gyrus, primary sensorimotor cortex, thalamus, and cuneus was related to longer response times; in contrast, higher activation in the superior parietal lobe was associated with shorter response times. Associations were independent of small vessel disease in the brain or other organs. In this group of middle-aged adults with T1D, the pathway linking chronic hyperglycemia with slower processing speed appears to include increased brain activation, but not small vessel disease. Activation in the superior parietal lobe may compensate for dysregulation in brain activation in the presence of hyperglycemia.

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.

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.

Adolescents with clinical type 1 diabetes display reduced red blood cell glucose transporter isoform 1 (GLUT1)

Type 1 diabetic (T1D) adolescent children on insulin therapy suffer episodes of both hyper- and hypoglycemic episodes. Glucose transporter isoform GLUT1 expressed in blood-brain barrier (BBB) and red blood cells (RBC) compensates for perturbed circulating glucose toward protecting the supply to brain and RBCs. We hypothesized that RBC-GLUT1 concentration, as a surrogate for BBB-GLUT1, is altered in T1D children. To test this hypothesis, we measured RBC-GLUT1 by enzyme-linked immunosorbent assay (ELISA) in T1D children (n = 72; mean age 15.3 ± 0.2 yr) and control children (CON; n = 11; mean age 15.6 ± 0.9 yr) after 12 h of euglycemia and during a hyperinsulinemic-hypoglycemic clamp with a nadir blood glucose of ~3.3 mmol/L for 90 min (clamp I) or ~3 mmol/L for 45 min (clamp II). Reduced baseline RBC-GLUT1 was observed in T1D (2.4 ± 0.17 ng/ng membrane protein); vs. CON (4.2 ± 0.61 ng/ng protein) (p < 0.0001). Additionally, baseline RBC-GLUT1 in T1D negatively correlated with hemoglobin A1c (HbA1c) (R = -0.23, p < 0.05) but not in CON (R = 0.06, p < 0.9). Acute decline in serum glucose to 3.3 mmol/L (90 min) or 3 mmol/L (45 min) did not change baseline RBC-GLUT1 in T1D or CON children. We conclude that reduced RBC-GLUT1 encountered in T1D, with no ability to compensate by increasing during acute hypoglycemia over the durations examined, may demonstrate a vulnerability of impaired RBC glucose transport (serving as a surrogate for BBB), especially in those with the worst control. We speculate that this may contribute to the perturbed cognition seen in T1D adolescents.

Severe hypoglycemia and cognitive decline in older people with type 2 diabetes: the Edinburgh type 2 diabetes study

OBJECTIVE

People with type 2 diabetes are at increased risk of age-related cognitive decline and dementia. Hypoglycemia is a candidate risk factor, but the direction of association between episodes of severe hypoglycemia and cognitive decline in type 2 diabetes remains uncertain.

RESEARCH DESIGN AND METHODS

In the Edinburgh Type 2 Diabetes Study, cognitive function was assessed in 831 adults with type 2 diabetes (aged 60-75 years) at baseline and after 4 years. Scores on seven neuropsychological tests were combined into a standardized general ability factor g. Self-reported history of severe hypoglycemia at baseline (history of hypoglycemia) and at follow-up (incident hypoglycemia) was recorded.

RESULTS

A history of hypoglycemia was reported by 9.3% of subjects, and 10.2% reported incident hypoglycemia. Incident hypoglycemia was associated with poorer cognitive ability at baseline (age- and sex-adjusted odds ratio for lowest tertile of g 2.04 [95% CI 1.25-3.31], P = 0.004). Both history of hypoglycemia and incident hypoglycemia were also associated with greater cognitive decline during follow-up (mean follow-up g adjusted for age, sex, and baseline g -0.25 vs. 0.03 [P = 0.02] and -0.28 vs. 0.04 [P = 0.01], respectively), including after addition of vascular risk factors and cardiovascular and microvascular disease to the models (-0.23 vs. 0.03 [P = 0.04] and -0.21 vs. 0.05 [P = 0.03], respectively).

CONCLUSIONS

The relationship between cognitive impairment and hypoglycemia appeared complex, with severe hypoglycemia associated with both poorer initial cognitive ability and accelerated cognitive decline.

Seizures and type 1 diabetes mellitus: current state of knowledge

In this review, we will try to analyze the possible coexistence between epilepsy or seizures and type 1 diabetes mellitus (T1DM), in order to establish if there is more than a casual association, and to investigate possible mechanisms underlying this link. Anti-glutamic acid decarboxylase antibodies (GAD-Abs) have been associated with T1DM and a great number of neurological diseases such as epilepsy. Epilepsy can be a feature of a large variety of autoimmune or inflammatory disorders. GAD-Abs can have a role at the basis of the possible link between epilepsy and T1DM, although their real pathogenetic mechanism in neurological diseases is still unknown. Metabolic conditions such as hypoglycemia and hyperglycemia, common problems in diabetic patients, may be also implicated, even if their underlying mechanism is minimally understood.

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.

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.

Quantitative EEG in type 1 diabetic adults with childhood exposure to severe hypoglycaemia: a 16 year follow-up study

AIMS/HYPOTHESIS

In diabetic children and adolescents, a history of severe hypoglycaemia (SH) has been associated with increased slow EEG activity and reduced cognition, possibly due to harmful effects of SH on the developing brain. In a group of type 1 diabetic patients with early exposure to SH, who had EEG abnormalities and reduced cognition in childhood, we have recently demonstrated that the reduced cognition may persist into adulthood. We have now assessed whether the reduced cognition was accompanied by lasting EEG abnormalities.

METHODS

In 1992-1993, we studied EEG and cognition in 28 diabetic children and 28 matched controls. 16 years later, we re-investigated the same participants, with 96% participation rate. Diabetic participants were classified as with (n = 9) or without (n = 18) early SH, defined as episodes with convulsions or loss of consciousness by 10 years of age. For each EEG band (delta, theta, alpha and beta) and cerebral region (frontocentral, temporal, and parietooccipital), we calculated relative amplitudes and amplitude asymmetry. We also calculated occipital alpha mean frequency, alpha peak frequency at maximum amplitude, alpha peak width, and theta regional mean frequencies. We examined whether these EEG measures, relative to age- and sex-matched controls, differed between diabetic participants with and without early SH.

RESULTS

We found no association of early SH with any of the EEG measures.

CONCLUSIONS/INTERPRETATION

Childhood SH was not associated with EEG abnormalities in young type 1 diabetic adults. Our findings suggest that the reduced adulthood cognition associated with childhood exposure to SH is not accompanied by lasting EEG abnormalities.