Effects of acute hypoglycemia on working memory and language processing in adults with and without type 1 diabetes

Glycemic Variability and Control by CGM in Healthy Older and Young Adults and Their Relationship With Diet

Continuous glucose monitoring (CGM) might be beneficial for investigating healthy aging since high glycemic variability may increase protein glycation, oxidative stress, and inflammation, resulting in vascular damage. Additionally, CGM data on the risks for hypoglycemia and hyperglycemia are scarce, have not been analyzed by individual day and night blocks, and have not been related to diet. Therefore, this study aimed to compare glucose parameters of healthy older and young adults and the relationship with diet. Participants were 34 young (age 20-35 years) and 27 older volunteers (age 60-75 years) with a normal glycated hemoglobin A1c less than 39 mmol/mol hemoglobin, free of disorders and medication. Twenty-four CGM-derived glucose parameters measured over 5 consecutive days were analyzed for whole days and for individual daytime and nighttime blocks. Dietary intake was determined by 3-day dietary record. Neither intraday nor interday glycemic variability differed between the healthy age groups. Glycemic control was good in both age groups, but somewhat poorer in older adults. The risk of hyperglycemia was higher and of hypoglycemia lower in older adults. During the daytime, mean and minimum glucose were higher in older adults. During the nighttime, age group differences were small. The carbohydrate intake correlated positively with glycemic variability in both age groups. The protein intake correlated positively with the hypoglycemic risk in young adults, but negatively in older adults. Results suggest that healthy aging does not increase glycemic variability and the risk of hypoglycemia. The effect of diet on hypoglycemic and hyperglycemic risk might change with aging.

Resting-State Functional MRI Reveals Altered Seed-Based Connectivity in Diabetic Osteoporosis Patients

Background

Diabetic osteoporosis (DOP) can cause abnormal brain neural activity, but its mechanism is still unclear. This study aims to further explore the abnormal functional connectivity between different brain regions based on the team's previous research.

Methods

Resting-state functional magnetic resonance imaging (rs-fMRI) data were obtained from 14 participants diagnosed with type 2 diabetes mellitus (T2DM) and osteoporosis. For comparison, data from 13 T2DM patients without osteoporosis were analyzed. The seed regions for functional connectivity (FC) analysis were chosen according to brain areas previously reported to exhibit abnormal regional homogeneity (ReHo).

Results

DOP patients exhibited significantly decreased BMD, T-scores, MoCA scores, and osteocalcin (OC) levels compared to controls (p<0.05). FC analysis revealed: 1) Reduced connectivity between the left middle temporal gyrus (increased ReHo) and middle occipital gyrus; 2) Enhanced connectivity between the right angular gyrus (increased ReHo) and left Rolandic operculum; 3) Weakened the left precuneus (increased ReHo) and right superior/left middle frontal gyri. These alterations correlated with deficits in visual processing, working memory, and executive function.

Conclusion

Distinct FC reorganization in DOP patients reflects synergistic effects of metabolic and skeletal pathologies on neural networks, potentially mediating cognitive decline through visual pathway disruption and prefrontal-default mode network decoupling. The findings highlight neuroimaging biomarkers for metabolic bone disease-related cognitive disorders.

Cognitive vulnerability to glucose fluctuations: A digital phenotype of neurodegeneration

INTRODUCTION

Cognition is reduced at low and high glucose, reflecting cognitive vulnerability to glucose (CVG) fluctuations. The impact of glucose fluctuations on the aging brain remains unclear. We examined whether CVG is associated with plasma biomarkers of Alzheimer's disease (AD) pathology and neurodegeneration.

METHODS

Participants included N = 114 adults with type 1 diabetes assessed for processing speed and sustained attention using ecological momentary assessment (EMA) combined with continuous glucose monitoring (CGM). We characterized associations between CVG and amyloid beta (Aβ) 42/40, phosphorylated tau (p-tau) 181 and 217, neurofilament light chain, and glial fibrillary acidic protein.

RESULTS

CVG was associated with all plasma biomarkers, except Aβ 42/40. CVG for sustained attention exhibited strong associations with p-tau biomarkers that persisted across covariate specifications.

DISCUSSION

CVG may be a useful digital phenotype of AD. It remains unclear whether CVG contributes to versus arises from neurodegeneration. We consider possible mechanisms linking cognitive vulnerability and long-term glucose variability to the development of neuropathology.

HIGHLIGHTS

Cognitive vulnerability to glucose (CVG) may be a useful digital phenotype of neurodegeneration. We used cognitive ecological momentary assessment and continuous glucose monitoring to investigate CVG's associations with plasma biomarkers. Associations of CVG for sustained attention and phosphorylated tau 181 remained significant across covariates. We discuss possible mechanisms relating glucose variability, cognition, and neurodegeneration.

Nocturnal hypoglycemia is associated with next day cognitive performance in adults with type 1 diabetes: Pilot data from the GluCog study

OBJECTIVE

 Individuals with type 1 diabetes (T1D) have increased risk for cognitive dysfunction and high rates of sleep disturbance. Despite associations between glycemia and cognitive performance using cross-sectional and experimental methods few studies have evaluated this relationship in a naturalistic setting, or the impact of nocturnal versus daytime hypoglycemia. Ecological Momentary Assessment (EMA) may provide insight into the dynamic associations between cognition, affective, and physiological states. The current study couples EMA data with continuous glucose monitoring (CGM) to examine the within-person impact of nocturnal glycemia on next day cognitive performance in adults with T1D. Due to high rates of sleep disturbance and emotional distress in people with T1D, the potential impacts of sleep characteristics and negative affect were also evaluated.

METHODS

 This pilot study utilized EMA in 18 adults with T1D to examine the impact of glycemic excursions, measured using CGM, on cognitive performance, measured via mobile cognitive assessment using the TestMyBrain platform. Multilevel modeling was used to test the within-person effects of nocturnal hypoglycemia and hyperglycemia on next day cognition.

RESULTS

 Results indicated that increases in nocturnal hypoglycemia were associated with slower next day processing speed. This association was not significantly attenuated by negative affect, sleepiness, or sleep quality.

CONCLUSIONS

 These results, while preliminary due to small sample size, showcase the power of intensive longitudinal designs using ambulatory cognitive assessment to uncover novel determinants of cognitive fluctuation in real world settings, an approach that may be utilized in other populations. Findings suggest reducing nocturnal hypoglycemia may improve cognition in adults with T1D.

Functional connectivity density aberrance in type 2 diabetes mellitus with and without mild cognitive impairment

Purpose

The objective of this study was to investigate alterations in functional connectivity density (FCD) mapping and their impact on functional connectivity (FC) among individuals diagnosed with Type 2 diabetes mellitus (T2DM) across different cognitive states. Moreover, the study sought to explore the potential association between aberrant FCD/FC patterns and clinical or cognitive variables.

Methods

A total of 211 participants were recruited for this study, consisting of 75 healthy controls (HCs), 89 T2DM patients with normal cognitive function (DMCN), and 47 T2DM patients with mild cognitive impairment (DMCI). The study employed FCD analysis to pinpoint brain regions exhibiting significant FCD alterations. Subsequently, these regions showing abnormal FCD served as seeds for FC analysis. Exploratory partial correlations were conducted to explore the relationship between clinical biochemical indicators, neuropsychological test scores, and altered FCD or FC.

Results

The FCD analysis revealed an increased trend in global FCD (gFCD), local FCD (lFCD), and long-range FCD (lrFCD) within the bilateral supramarginal gyrus (SMG) among individuals with DMCN. Additionally, significant lFCD alterations were observed in the right inferior frontal gyrus and left precuneus when comparing DMCN to HCs and DMCI.

Conclusion

When comparing individuals with T2DM and healthy controls (HCs), it was revealed that DMCN exhibited significant improvements in FCD. This suggests that the brain may employ specific compensatory mechanisms to maintain normal cognitive function at this stage. Our findings provide a novel perspective on the neural mechanisms involved in cognitive decline associated with T2DM.

Multimodal In-Vehicle Hypoglycemia Warning for Drivers With Type 1 Diabetes: Design and Evaluation in Simulated and Real-World Driving

BACKGROUND

Hypoglycemia threatens cognitive function and driving safety. Previous research investigated in-vehicle voice assistants as hypoglycemia warnings. However, they could startle drivers. To address this, we combine voice warnings with ambient LEDs.

OBJECTIVE

The study assesses the effect of in-vehicle multimodal warning on emotional reaction and technology acceptance among drivers with type 1 diabetes.

METHODS

Two studies were conducted, one in simulated driving and the other in real-world driving. A quasi-experimental design included 2 independent variables (blood glucose phase and warning modality) and 1 main dependent variable (emotional reaction). Blood glucose was manipulated via intravenous catheters, and warning modality was manipulated by combining a tablet voice warning app and LEDs. Emotional reaction was measured physiologically via skin conductance response and subjectively with the Affective Slider and tested with a mixed-effect linear model. Secondary outcomes included self-reported technology acceptance. Participants were recruited from Bern University Hospital, Switzerland.

RESULTS

The simulated and real-world driving studies involved 9 and 10 participants with type 1 diabetes, respectively. Both studies showed significant results in self-reported emotional reactions (P<.001). In simulated driving, neither warning modality nor blood glucose phase significantly affected self-reported arousal, but in real-world driving, both did (F2,68=4.3; P<.05 and F2,76=4.1; P=.03). Warning modality affected self-reported valence in simulated driving (F2,68=3.9; P<.05), while blood glucose phase affected it in real-world driving (F2,76=9.3; P<.001). Skin conductance response did not yield significant results neither in the simulated driving study (modality: F2,68=2.46; P=.09, blood glucose phase: F2,68=0.3; P=.74), nor in the real-world driving study (modality: F2,76=0.8; P=.47, blood glucose phase: F2,76=0.7; P=.5). In both simulated and real-world driving studies, the voice+LED warning modality was the most effective (simulated: mean 3.38, SD 1.06 and real-world: mean 3.5, SD 0.71) and urgent (simulated: mean 3.12, SD 0.64 and real-world: mean 3.6, SD 0.52). Annoyance varied across settings. The standard warning modality was the least effective (simulated: mean 2.25, SD 1.16 and real-world: mean 3.3, SD 1.06) and urgent (simulated: mean 1.88, SD 1.55 and real-world: mean 2.6, SD 1.26) and the most annoying (simulated: mean 2.25, SD 1.16 and real-world: mean 1.7, SD 0.95). In terms of preference, the voice warning modality outperformed the standard warning modality. In simulated driving, the voice+LED warning modality (mean rank 1.5, SD rank 0.82) was preferred over the voice (mean rank 2.2, SD rank 0.6) and standard (mean rank 2.4, SD rank 0.81) warning modalities, while in real-world driving, the voice+LED and voice warning modalities were equally preferred (mean rank 1.8, SD rank 0.79) to the standard warning modality (mean rank 2.4, SD rank 0.84).

CONCLUSIONS

Despite the mixed results, this paper highlights the potential of implementing voice assistant-based health warnings in cars and advocates for multimodal alerts to enhance hypoglycemia management while driving.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05183191; https://classic.clinicaltrials.gov/ct2/show/NCT05183191, ClinicalTrials.gov NCT05308095; https://classic.clinicaltrials.gov/ct2/show/NCT05308095.

Dynamic associations between glucose and ecological momentary cognition in Type 1 Diabetes

Type 1 diabetes (T1D) is a chronic condition characterized by glucose fluctuations. Laboratory studies suggest that cognition is reduced when glucose is very low (hypoglycemia) and very high (hyperglycemia). Until recently, technological limitations prevented researchers from understanding how naturally-occurring glucose fluctuations impact cognitive fluctuations. This study leveraged advances in continuous glucose monitoring (CGM) and cognitive ecological momentary assessment (EMA) to characterize dynamic, within-person associations between glucose and cognition in naturalistic environments. Using CGM and EMA, we obtained intensive longitudinal measurements of glucose and cognition (processing speed, sustained attention) in 200 adults with T1D. First, we used hierarchical Bayesian modeling to estimate dynamic, within-person associations between glucose and cognition. Consistent with laboratory studies, we hypothesized that cognitive performance would be reduced at low and high glucose, reflecting cognitive vulnerability to glucose fluctuations. Second, we used data-driven lasso regression to identify clinical characteristics that predicted individual differences in cognitive vulnerability to glucose fluctuations. Large glucose fluctuations were associated with slower and less accurate processing speed, although slight glucose elevations (relative to person-level means) were associated with faster processing speed. Glucose fluctuations were not related to sustained attention. Seven clinical characteristics predicted individual differences in cognitive vulnerability to glucose fluctuations: age, time in hypoglycemia, lifetime severe hypoglycemic events, microvascular complications, glucose variability, fatigue, and neck circumference. Results establish the impact of glucose on processing speed in naturalistic environments, suggest that minimizing glucose fluctuations is important for optimizing processing speed, and identify several clinical characteristics that may exacerbate cognitive vulnerability to glucose fluctuations.

Effectiveness and User Perception of an In-Vehicle Voice Warning for Hypoglycemia: Development and Feasibility Trial

BACKGROUND

Hypoglycemia is a frequent and acute complication in type 1 diabetes mellitus (T1DM) and is associated with a higher risk of car mishaps. Currently, hypoglycemia can be detected and signaled through flash glucose monitoring or continuous glucose monitoring devices, which require manual and visual interaction, thereby removing the focus of attention from the driving task. Hypoglycemia causes a decrease in attention, thereby challenging the safety of using such devices behind the wheel. Here, we present an investigation of a hands-free technology-a voice warning that can potentially be delivered via an in-vehicle voice assistant.

OBJECTIVE

This study aims to investigate the feasibility of an in-vehicle voice warning for hypoglycemia, evaluating both its effectiveness and user perception.

METHODS

We designed a voice warning and evaluated it in 3 studies. In all studies, participants received a voice warning while driving. Study 0 (n=10) assessed the feasibility of using a voice warning with healthy participants driving in a simulator. Study 1 (n=18) assessed the voice warning in participants with T1DM. Study 2 (n=20) assessed the voice warning in participants with T1DM undergoing hypoglycemia while driving in a real car. We measured participants' self-reported perception of the voice warning (with a user experience scale in study 0 and with acceptance, alliance, and trust scales in studies 1 and 2) and compliance behavior (whether they stopped the car and reaction time). In addition, we assessed technology affinity and collected the participants' verbal feedback.

RESULTS

Technology affinity was similar across studies and approximately 70% of the maximal value. Perception measure of the voice warning was approximately 62% to 78% in the simulated driving and 34% to 56% in real-world driving. Perception correlated with technology affinity on specific constructs (eg, Affinity for Technology Interaction score and intention to use, optimism and performance expectancy, behavioral intention, Session Alliance Inventory score, innovativeness and hedonic motivation, and negative correlations between discomfort and behavioral intention and discomfort and competence trust; all P<.05). Compliance was 100% in all studies, whereas reaction time was higher in study 1 (mean 23, SD 5.2 seconds) than in study 0 (mean 12.6, SD 5.7 seconds) and study 2 (mean 14.6, SD 4.3 seconds). Finally, verbal feedback showed that the participants preferred the voice warning to be less verbose and interactive.

CONCLUSIONS

This is the first study to investigate the feasibility of an in-vehicle voice warning for hypoglycemia. Drivers find such an implementation useful and effective in a simulated environment, but improvements are needed in the real-world driving context. This study is a kickoff for the use of in-vehicle voice assistants for digital health interventions.

Glycemic Variability and Fluctuations in Cognitive Status in Adults With Type 1 Diabetes (GluCog): Observational Study Using Ecological Momentary Assessment of Cognition

BACKGROUND

Individuals with type 1 diabetes represent a population with important vulnerabilities to dynamic physiological, behavioral, and psychological interactions, as well as cognitive processes. Ecological momentary assessment (EMA), a methodological approach used to study intraindividual variation over time, has only recently been used to deliver cognitive assessments in daily life, and many methodological questions remain. The Glycemic Variability and Fluctuations in Cognitive Status in Adults with Type 1 Diabetes (GluCog) study uses EMA to deliver cognitive and self-report measures while simultaneously collecting passive interstitial glucose in adults with type 1 diabetes.

OBJECTIVE

We aimed to report the results of an EMA optimization pilot and how these data were used to refine the study design of the GluCog study. An optimization pilot was designed to determine whether low-frequency EMA (3 EMAs per day) over more days or high-frequency EMA (6 EMAs per day) for fewer days would result in a better EMA completion rate and capture more hypoglycemia episodes. The secondary aim was to reduce the number of cognitive EMA tasks from 6 to 3.

METHODS

Baseline cognitive tasks and psychological questionnaires were completed by all the participants (N=20), followed by EMA delivery of brief cognitive and self-report measures for 15 days while wearing a blinded continuous glucose monitor. These data were coded for the presence of hypoglycemia (<70 mg/dL) within 60 minutes of each EMA. The participants were randomized into group A (n=10 for group A and B; starting with 3 EMAs per day for 10 days and then switching to 6 EMAs per day for an additional 5 days) or group B (N=10; starting with 6 EMAs per day for 5 days and then switching to 3 EMAs per day for an additional 10 days).

RESULTS

A paired samples 2-tailed t test found no significant difference in the completion rate between the 2 schedules (t17=1.16; P=.26; Cohen dz=0.27), with both schedules producing >80% EMA completion. However, more hypoglycemia episodes were captured during the schedule with the 3 EMAs per day than during the schedule with 6 EMAs per day.

CONCLUSIONS

The results from this EMA optimization pilot guided key design decisions regarding the EMA frequency and study duration for the main GluCog study. The present report responds to the urgent need for systematic and detailed information on EMA study designs, particularly those using cognitive assessments coupled with physiological measures. Given the complexity of EMA studies, choosing the right instruments and assessment schedules is an important aspect of study design and subsequent data interpretation.

Nutritional Composition and Environmental Impact of Meals Selected in Workplace Canteens before and after an Intervention Promoting the Adherence to the Mediterranean Diet

Enhancing healthy and sustainable food systems is one of the key goals of the current European Commission policy. In this light, the creation of a food environment where people are properly informed about the healthiness and sustainability of food choices is essential. This study aimed to evaluate the nutritional profile and the environmental impact of meals consumed in a workplace canteen in Italy in the presence of a nudge (i.e., the Double Pyramid logo) combined with a web-based application promoting the Mediterranean Diet. Energy and nutrient contents and the carbon, water, and ecological footprints of 29,776 meals were compared across three subsequent periods (from June to April) through one-way ANOVA. Although the choice of dishes labelled with the Double Pyramid logo was comparable across periods, the selection of fish- and plant-based dishes increased from +2% (fish, vegetables) up to +17% (whole-grain cereals), with a concurrent reduction of meat-based options (−2%). Although the consumption of healthy items increased (p < 0.001), they were not added as a replacement for alternative options, leading to a higher content in energy (p < 0.001) and nutrients (p < 0.001) and worse environmental footprints, contrarily to what was observed when data were adjusted for energy. The intervention significantly improved food choices; however, as the higher selection of desired dishes was not adequately compensated for, it was not fully effective.

The fractional amplitude of low-frequency fluctuations signals related to amyloid uptake in high-risk populations—A pilot fMRI study

Background

Patients with type 2 diabetes mellitus (T2DM) and subjective cognitive decline (SCD) have a higher risk to develop Alzheimer's Disease (AD). Resting-state-functional magnetic resonance imaging (rs-fMRI) was used to document neurological involvement in the two groups from the aspect of brain dysfunction. Accumulation of amyloid-β (Aβ) starts decades ago before the onset of clinical symptoms and may already have been associated with brain function in high-risk populations. However, this study aims to compare the patterns of fractional amplitude of low-frequency fluctuations (fALFF) maps between cognitively normal high-risk groups (SCD and T2DM) and healthy elderly and evaluate the association between regional amyloid deposition and local fALFF signals in certain cortical regions.

Materials and methods

A total of 18 T2DM, 11 SCD, and 18 healthy elderlies were included in this study. The differences in the fALFF maps were compared between HC and high-risk groups. Regional amyloid deposition and local fALFF signals were obtained and further correlated in two high-risk groups.

Results

Compared to HC, the altered fALFF signals of regions were shown in SCD such as the left posterior cerebellum, left putamen, and cingulate gyrus. The T2DM group illustrated altered neural activity in the superior temporal gyrus, supplementary motor area, and precentral gyrus. The correlation between fALFF signals and amyloid deposition was negative in the left anterior cingulate cortex for both groups. In the T2DM group, a positive correlation was shown in the right occipital lobe and left mesial temporal lobe.

Conclusion

The altered fALFF signals were demonstrated in high-risk groups compared to HC. Very early amyloid deposition in SCD and T2DM groups was observed to affect the neural activity mainly involved in the default mode network (DMN).

Driving with Type 1 Diabetes: Real-World Evidence to Support Starting Glucose Level and Frequency of Monitoring During Journeys

There is limited evidence supporting the recommendation that drivers with insulin-treated diabetes need to start journeys with glucose >90 mg/dL. Glucose levels of drivers with type 1 diabetes were monitored for 3 weeks using masked continuous glucose monitoring (CGM). Eighteen drivers (median [IQR] age 40 [35, 51] years; 11 men) undertook 475 trips (duration 15 [13, 21] min). Hypoglycemia did not occur in any trip starting with glucose >90 mg/dL (92%; n = 436). Thirteen drivers recorded at least one trip (total n = 39) starting with glucose <90 mg/dL. Among these, driving glucose was <70 mg/dL in five drivers (38%) during 10 trips (26%). Among five drivers (28%), a ≥ 36 mg/dL drop was observed within 20 min of starting their journey. Journey duration was positively associated with maximum glucose change. These findings support current guidelines to start driving with glucose >90 mg/dL, and to be aware that glucose levels may change significantly within 20 min. A CGM-based, in-vehicle display could provide glucose information and alerts that are compatible with safe driving. Clinical Trial Registration number: ACTRN12617000520336.

A multimodal meta-analysis of regional structural and functional brain alterations in type 2 diabetes

Neuroimaging studies have identified brain structural and functional alterations of type 2 diabetes mellitus (T2DM) patients; however, there is no systematic information on the relations between abnormalities in these two domains. We conducted a multimodal meta-analysis of voxel-based morphometry and regional resting-state functional MRI studies in T2DM, including fifteen structural datasets (693 patients and 684 controls) and sixteen functional datasets (378 patients and 358 controls). We found, in patients with T2DM compared to controls, conjoint decreased regional gray matter volume (GMV) and altered intrinsic activity mainly in the default mode network including bilateral superior temporal gyrus/Rolandic operculum, left middle and inferior temporal gyrus, and left supramarginal gyrus; decreased GMV alone in the limbic system; and functional abnormalities alone in the cerebellum, insula, and visual cortex. This meta-analysis identified complicated patterns of conjoint and dissociated brain alterations in T2DM patients, which may help provide new insight into the neuropathology of T2DM.

Extreme Glycemic Fluctuations Debilitate NRG1, ErbB Receptors and Olig1 Function: Association with Regeneration, Cognition and Mood Alterations During Diabetes

Neuronal regeneration is crucial for maintaining intact neural interactions for perpetuation of cognitive and emotional functioning. The NRG1-ErbB receptor signaling is a key pathway for regeneration in adult brain and also associated with learning and mood stabilization by modulating synaptic transmission. Extreme glycemic stress is known to affect NRG1-ErbB-mediated regeneration in brain; yet, it remains unclear how the ErbB receptor subtypes are differentially affected due to such metabolic variations. Here, we assessed the alterations in NRG1, ErbB receptor subtypes to study the regenerative potential, both in rodents as well as in neuronal and glial cell models of hyperglycemia and hypoglycemic insults during hyperglycemia. The pro-oxidant and anti-oxidant status leading to degenerative changes in brain regions were determined. The spatial memory and anxiogenic behaviour of experimental rodents were tested using 'T' maze and Elevated Plus Maze. Our data revealed that the extreme glycemic discrepancies during diabetes and recurrent hypoglycemia lead to altered expression of NRG1, ErbB receptor subtypes, Syntaxin1 and Olig1 that shows association with impaired regeneration, synaptic dysfunction, demyelination, cognitive deficits and anxiety.

Regional Spontaneous Neural Activity Alterations in Type 2 Diabetes Mellitus: A Meta-Analysis of Resting-State Functional MRI Studies

Objective: Resting-state functional magnetic resonance imaging (rs-fMRI) studies have revealed inconsistent regional spontaneous neural activity alterations in patients with type 2 diabetes mellitus (T2DM). The aim of our meta-analysis was to identify concordant regional spontaneous neural activity abnormalities in patients with T2DM. Methods: A systematic search was conducted to identify voxel-based rs-fMRI studies comparing T2DM patients with healthy controls. The permutation of subject images seed-based d mapping (SDM) was used to quantitatively estimate the regional spontaneous neural activity abnormalities in patients with T2DM. Metaregression was conducted to examine the associations between clinical characteristics and functional alterations. Results: A total of 16 studies with 19 datasets including 434 patients with T2DM and 391 healthy controls were included. Patients with T2DM showed hypoactivity in the right medial superior frontal gyrus, right superior temporal gyrus, and left lingual gyrus, whereas hyperactivity in the right cerebellum. Metaregression analysis identified negative correlation between regional activity in the medial superior frontal and anterior cingulate gyri and illness duration of patients with T2DM. Conclusion: The patterns of regional spontaneous neural activity alterations, characterized by hypoactivity in the medial pre-frontal cortex, visual cortex, and superior temporal gyrus, whereas hyperactivity in the cerebellum, might represent the underlying neuropathological mechanisms of T2DM.

The consequences of hypoglycaemia

Hypoglycaemia (blood glucose concentration below the normal range) has been recognised as a complication of insulin treatment from the very first days of the discovery of insulin, and remains a major concern for people with diabetes, their families and healthcare professionals today. Acute hypoglycaemia stimulates a stress response that acts to restore circulating glucose, but plasma glucose concentrations can still fall too low to sustain normal brain function and cardiac rhythm. There are long-term consequences of recurrent hypoglycaemia, which are still not fully understood. This paper reviews our current understanding of the acute and cumulative consequences of hypoglycaemia in insulin-treated diabetes.

Recurrent non-severe hypoglycemia aggravates cognitive decline in diabetes and induces mitochondrial dysfunction in cultured astrocytes

The present study aimed to determine the relationship between astrocytes and recurrent non-severe hypoglycemia (RH)2 -associated cognitive decline in diabetes. RH induced cognitive impairment and neuronal cell death in the cerebral cortex of diabetic mice, accompanied by excessive activation of astrocytes. Levels of the neurotrophins BDNF and GDNF, together with BDNF and GDNF- related signaling, were downregulated by RH. In vitro, recurrent low glucose (RLG)3 impaired cell viability and induced apoptosis of high-glucose cultured astrocytes. Accumulating mitochondrial ROS and dysregulated mitochondrial functions, including abnormal morphology, decreased membrane potential, downregulated ATP levels, and disrupted bioenergetic status, were observed in these cells. SS-31 mediated protection of mitochondrial functions reversed RLG-induced cell viability defects and neurotrophin production. These findings demonstrate that RH induced astrocyte overactivation and mitochondrial dysfunction, leading to astrocyte-derived neurotrophin disturbance, which might contribute to diabetic cognitive decline. Targeting astrocyte mitochondria might represent a neuroprotective therapy for hypoglycemia-associated neurodegeneration in diabetes.

The role of explicit memory in syntactic persistence: Effects of lexical cueing and load on sentence memory and sentence production

Speakers’ memory of sentence structure can persist and modulate the syntactic choices of subsequent utterances (i.e., structural priming). Much research on structural priming posited a multifactorial account by which an implicit learning process and a process related to explicit memory jointly contribute to the priming effect. Here, we tested two predictions from that account: (1) that lexical repetition facilitates the retrieval of sentence structures from memory; (2) that priming is partly driven by a short-term explicit memory mechanism with limited resources. In two pairs of structural priming and sentence structure memory experiments, we examined the effects of structural priming and its modulation by lexical repetition as a function of cognitive load in native Dutch speakers. Cognitive load was manipulated by interspersing the prime and target trials with easy or difficult mathematical problems. Lexical repetition boosted both structural priming (Experiments 1a–2a) and memory for sentence structure (Experiments 1b–2b) and did so with a comparable magnitude. In Experiment 1, there were no load effects, but in Experiment 2, with a stronger manipulation of load, both the priming and memory effects were reduced with a larger cognitive load. The findings support an explicit memory mechanism in structural priming that is cue-dependent and attention-demanding, consistent with a multifactorial account of structural priming.

Diabetic Cognitive Dysfunction: From Bench to Clinic

Type 2 diabetes increases the risk of developing cognitive dysfunction in the elderly in the form of short-term memory and executive function impairment. Genetic and diet-induced models of type 2 diabetes further support this link, displaying deficits in working memory, learning, and memory performance. The risk factors for diabetic cognitive dysfunction include vascular disease, hypoglycaemia, hyperlipidaemia, adiposity, insulin resistance, lifestyle factors, and genetic factors. Using neuronal imaging technologies, diabetic patients with cognitive dysfunction show atrophy of the whole brain, particularly the grey matter, hippocampus and amygdala; increased volume of the ventricular and white matter; brain infarcts; impaired network integrity; abnormal microstructure; and reduced cerebral blood flow and amplitude of low-frequency fluctuations. The pathogenesis of type 2 diabetes with cognitive dysfunction involves hyperglycaemia, macrovascular and microvascular diseases, insulin resistance, inflammation, apoptosis, and disorders of neurotransmitters. Large clinical trials may offer further proof of biomarkers and risk factors for diabetic cognitive dysfunction. Advanced neuronal imaging technologies and novel disease animal models will assist in elucidating the precise pathogenesis and to provide better therapeutic interventions and treatment.

Hypoglycemic thalamic activation in type 1 diabetes is associated with preserved symptoms despite reduced epinephrine

Brain responses to low plasma glucose may be key to understanding the behaviors that prevent severe hypoglycemia in type 1 diabetes. This study investigated the impact of long duration, hypoglycemia aware type 1 diabetes on cerebral blood flow responses to hypoglycemia. Three-dimensional pseudo-continuous arterial spin labeling magnetic resonance imaging was performed in 15 individuals with type 1 diabetes and 15 non-diabetic controls during a two-step hyperinsulinemic glucose clamp. Symptom, hormone, global cerebral blood flow and regional cerebral blood flow responses to hypoglycemia were measured. Epinephrine release during hypoglycemia was attenuated in type 1 diabetes, but symptom score rose comparably in both groups. A rise in global cerebral blood flow did not differ between groups. Regional cerebral blood flow increased in the thalamus and fell in the hippocampus and temporal cortex in both groups. Type 1 diabetes demonstrated lesser anterior cingulate cortex activation; however, this difference did not survive correction for multiple comparisons. Thalamic cerebral blood flow change correlated with autonomic symptoms, and anterior cingulate cortex cerebral blood flow change correlated with epinephrine response across groups. The thalamus may thus be involved in symptom responses to hypoglycemia, independent of epinephrine action, while anterior cingulate cortex activation may be linked to counterregulation. Activation of these regions may have a role in hypoglycemia awareness and avoidance of problematic hypoglycemia.

Abnormal Functional Connectivity Density in New-Onset Type 1 Diabetes Mellitus Children: A Resting-State Functional Magnetic Resonance Imaging Study

Type 1 diabetes mellitus (T1DM) causes cognitive changes in children, which may be due to deficits in brain functions. It is unclear whether T1DM children will have brain functional changes during the initial stage of the disease. We aimed to investigate the changes in the functional brain network topology in children with new-onset T1DM. In this study, 35 new-onset T1DM children and 33 age-, sex-matched healthy controls underwent resting-state fMRI. The whole brain functional connectivity density (FCD) analysis and seed-based functional connectivity (FC) analysis were performed to investigate the changes in functional brain networks in new-onset T1DM children when compared with the controls. Pearson correlational analysis was used to explore the correlation between FCD value of differential brain areas and clinical variables in T1DM children. Compared with the controls, children with new-onset T1DM exhibited significantly decreased FCDs of the right inferior temporal gyrus (ITG) and the right posterior cingulate cortex (PCC). In the subsequent FC analysis, decreased FC was found between right PCC and right cuneus and increased FC was found between right ITG and left orbital part of inferior frontal gyrus in children with new-onset T1DM compared to the controls. The FCD values of right ITG and PCC did not correlate with HbA1c, blood glucose level before imaging, and full-scale intelligence quotient (IQ) in T1DM children. These results revealed that T1DM affect the functional activity of the immature brain at the initial stage. These findings also indicate a decrease in regional brain function and abnormalities in temporal-frontal and limbic-occipital circuitry in children with new-onset T1DM, and highlight the effects of T1DM on children's brain networks involved in visual process and memory, which may contribute to the cognition impairments observed in children with T1DM.

Characteristics influencing expected cognitive performance during hypoglycaemia in type 2 diabetes

BACKGROUND

Acute hypoglycaemia is associated with cognitive impairment in patients with type 2 diabetes. However, there is limited understanding of the relationship between patients' expected cognitive difficulties and their objectively-measured deficits during non-severe hypoglycaemia.

OBJECTIVE

This report investigates demographic and clinical factors associated with the discrepancy between expected (i.e., self-evaluated) and measurable (i.e., neuropsychological) cognitive functions in patients with type 2 diabetes during acute non-severe hypoglycaemia.

METHODS

We performed an analysis of factors associated with the relationship between expected and measurable cognitive performance for data collected from a cohort of patients with type 2 diabetes (N = 25). Patients attended two experimental visits during which we performed hyper-insulinaemic glucose clamping; (i) non-severe hypoglycaemic clamp (plasma glucose (PG): 3.1 ± 0.3 mmol/L) and (ii) normoglycaemic clamp (PG: 5.8 ± 0.3 mmol/L), as part of a double-blinded cross-over study. During hypoglycaemia, patients' expected cognitive performance was assessed with a visual analogue scale after which objective cognitive functions were assessed with a neuropsychological test battery. We computed a global 'cognitive discrepancy' composite variable with score values on a scale between -10 and +10 using a novel statistical formula that creates a discrepancy score between subjective and objective cognition. Positive values reflect more expected than objectively-measured difficulties, while negative values reflect disproportionately more objectively-measured than expected cognitive difficulties. We used paired samples t-tests to compare degree of cognitive discrepancy between conditions of hypo- and normoglycaemia, while multiple regression analysis was performed to identify factors associated with the degree and direction of the cognitive discrepancy. The significance level for the analyses was p ≤ 0.05 (two-tailed).

RESULTS

Patients generally underestimated their cognitive abilities (M = 1.6, SD = 3.3) during hypoglycaemia compared to normoglycaemia (M = -1.0, SD = 3.5) (p = 0.2), t(23) = 2.9, p < 0.01. Underestimation of cognitive capacity during hypoglycaemia was more pronounced for patients with younger age (β = 0.5, p = 0.02), higher verbal IQ (β = 0.5, p = 0.03), and more hypoglycaemia-related shakiness (β = 0.4, p = 0.03).

LIMITATIONS

The modest sample size limits the generalizability of the findings.

CONCLUSIONS

Patients with type 2 diabetes underestimated their cognitive abilities during non-severe hypoglycaemic states, especially those with younger age, higher IQ, and more hypoglycaemia-related shakiness. These patients may thus have excessive preoccupations with their cognitive difficulties in relation to cognitively challenging daily life situations.

Type-1 diabetes shapes working memory processing strategies

BACKGROUND

Type 1 diabetes (T1D) is a metabolic disorder characterized by recurrent hypo- and hyperglycemic episodes, whose clinical development has been associated with cognitive and working memory (WM) deficits.

OBJECTIVE

To contrast quantitative electroencephalography (qEEG) measures between young patients with T1D and healthy controls while performing a visuospatial WM task with two memory load levels and facial emotional stimuli.

METHODS

Four or five neutral or happy faces were sequentially and pseudo-randomly presented in different spatial locations, followed by subsequent sequences displaying the reversed spatial order or any other. Participants were instructed to discriminate between these two alternatives during EEG recording.

RESULTS

A significant increase in the absolute power of the delta and theta bands, distributed mainly over the frontal region was found during task execution, with a slight decrease of alpha band power in both groups but mainly in control individuals. However, these changes were more pronounced in the T1D patients, and reached their maximum level during the WM encoding phase, even on trials with the lower memory load. In contrast, changes seemed to occur more gradually in controls and results differed significantly only on the trials with the higher WM load.

CONCLUSIONS

These results reflect adaptive WM-processing mechanisms in which cognitive strategies have evolved in T1D patients in order to meet task demands.

The effect of lithium chloride on the attenuation of cognitive impairment in experimental hypoglycemic rats

BACKGROUND

Hypoglycemia is the most common complication in the treatment of diabetes mellitus. Accumulating evidence indicated that severe hypoglycemia could induce cognitive impairment. However, the molecular mechanism of regulating this progress is largely unknown.

METHODS

We established a model of insulin-induced recurrent hypoglycemia in adult male Wistar rats (n = 40). Lithium chloride was injected after hypoglycemia once a day for consecutive 30 days. The loss of cognition function was evaluated by water maze test in these hypoglycemic rats. Glial cells activation and Wnt and inflammatory cytokines IL-1β, IL-6, IL-4, IL-10, TGFβ and TNFα expression were further examined to determine the mechanism of cognitive function impairment.

RESULTS

Hypoglycemia could induce impairment of cognitive function in rats and administration of lithium chloride could partly attenuate cognitive impairment compared to the control (p < 0.05). Lithium chloride could significantly up-regulate Wnt signaling and reduce hypoglycemia-induced neuronal death, glial cells activation and inflammatory response in the hippocampus of rats compared to the control (p < 0.05). The efficacy of lithium chloride could be reversed by injecting canonical Wnt signaling antagonist the dickkopf homolog 1.

CONCLUSION

Lithium chloride attenuated hypoglycemia-induced cognitive function impairment in rats; and it was associated with Wnt signaling up-regulation and reduction of inflammatory response. Our results suggested that activating Wnt signaling pathways and inhibiting inflammatory response were the therapeutic potential to prevent hypoglycemia-induced neurological damage.

Association of Type 1 Diabetes With Standardized Test Scores of Danish Schoolchildren

IMPORTANCE

Type 1 diabetes has been associated with cardiovascular disease and late complications such as retinopathy and nephropathy. However, it is unclear whether there is an association between type 1 diabetes and school performance in children.

OBJECTIVE

To compare standardized reading and mathematics test scores of schoolchildren with type 1 diabetes vs those without diabetes.

DESIGN, SETTING, AND PARTICIPANTS

Population-based retrospective cohort study from January 1, 2011, to December 31, 2015 (end date of follow-up), including Danish public schoolchildren attending grades 2, 3, 4, 6, and 8. Test scores were obtained in math (n = 524 764) and reading (n = 1 037 006). Linear regression models compared outcomes with and without adjustment for socioeconomic characteristics.

EXPOSURES

Type 1 diabetes.

MAIN OUTCOMES AND MEASURES

Primary outcomes were pooled test scores in math and reading (range, 1-100).

RESULTS

Among 631 620 included public schoolchildren, the mean (SD) age was 10.31 (SD, 2.42) years, and 51% were male; 2031 had a confirmed diagnosis of type 1 diabetes. Overall, the mean combined score in math and reading was 56.11 (SD, 24.93). There were no significant differences in test scores found between children with type 1 diabetes (mean, 56.56) and children without diabetes (mean, 56.11; difference, 0.45 [95% CI, -0.31 to 1.22]). The estimated difference in test scores between children with and without type 1 diabetes from a linear regression model with adjustment for grade, test topic, and year was 0.24 (95% CI, -0.90 to 1.39) and 0.45 (95% CI, -0.58 to 1.49) with additional adjustment for socioeconomic status.

CONCLUSIONS AND RELEVANCE

Among Danish public schoolchildren, there was no significant difference in standardized reading and mathematics test scores of children with type 1 diabetes compared with test scores of children without diabetes.

A Systematic Review and Meta-analysis of Executive Function Performance in Type 1 Diabetes Mellitus

OBJECTIVE

The aims of the study were to examine the current evidence for executive function (EF) performance differences between groups with type 1 diabetes mellitus (T1DM) and nondiabetic control groups during adolescence and early adulthood and to explore the relationships between EF and diabetes-related risk factors.

METHODS

A systematic review of the literature examining EF performance in groups with T1DM was conducted according to the PRISMA guidelines. Electronic database searches for published and unpublished literature yielded a final set of 26 articles after application of inclusion and exclusion criteria. A meta-analysis was conducted on a subset of these articles (n = 17) comparing EF performance in T1DM and control groups, across a total sample size of 1619.

RESULTS

Sixteen of 26 studies found significantly lower EF on at least one task in groups with T1DM. Meta-analyses of the performance difference between T1DM groups and control groups without diabetes showed that inhibition (g = -0.28, p < .001), working memory (g = -0.34, p < .001), set-shifting (g = -0.31, p = .012), and overall EF performance across these domains (g = -0.42, p < .001) were all significantly lower in groups with T1DM. Performance on specific EF domains also seemed to be differentially associated with early age of diabetes onset, chronic hyperglycemia and its complications, and severe hypoglycemia.

CONCLUSIONS

T1DM and its associated risk factors are related to subtle impairments across the inhibition, working memory, and set-shifting domains of EF. Lower EF may be a key factor contributing to behavioral and clinical problems experienced by individuals with T1DM.

Effects of hypoglycaemia on working memory and regional cerebral blood flow in type 1 diabetes: a randomised, crossover trial

AIMS/HYPOTHESIS

The aim of this randomised, crossover trial was to compare cognitive functioning and associated brain activation patterns during hypoglycaemia (plasma glucose [PG] just below 3.1 mmol/l) and euglycaemia in individuals with type 1 diabetes mellitus.

METHODS

In this patient-blinded, crossover study, 26 participants with type 1 diabetes mellitus attended two randomised experimental visits: one hypoglycaemic clamp (PG 2.8 ± 0.2 mmol/l, approximate duration 55 min) and one euglycaemic clamp (PG 5.5 mmol/l ± 10%). PG levels were maintained by hyperinsulinaemic glucose clamping. Cognitive functioning was assessed during hypoglycaemia and euglycaemia conditions using a modified version of the digit symbol substitution test (mDSST) and control DSST (cDSST). Simultaneously, regional cerebral blood flow (rCBF) was measured in pre-specified brain regions by six H₂¹⁵O-positron emission tomographies (PET) per session.

RESULTS

Working memory was impaired during hypoglycaemia as indicated by a statistically significantly lower mDSST score (estimated treatment difference [ETD] -0.63 [95% CI -1.13, -0.14], p = 0.014) and a statistically significantly longer response time (ETD 2.86 s [7%] [95% CI 0.67, 5.05], p = 0.013) compared with euglycaemia. During hypoglycaemia, mDSST task performance was associated with increased activity in the frontal lobe regions, superior parietal lobe and thalamus, and decreased activity in the temporal lobe regions (p < 0.05). Working memory activation (mDSST - cDSST) statistically significantly increased blood flow in the striatum during hypoglycaemia (ETD 0.0374% [95% CI 0.0157, 0.0590], p = 0.002).

CONCLUSIONS/INTERPRETATION

During hypoglycaemia (mean PG 2.9 mmol/l), working memory performance was impaired. Altered performance was associated with significantly increased blood flow in the striatum, a part of the basal ganglia implicated in regulating motor functions, memory, language and emotion.

TRIAL REGISTRATION

NCT01789593, clinicaltrials.gov FUNDING: This study was funded by Novo Nordisk.

Standardizing Clinically Meaningful Outcome Measures Beyond HbA1c for Type 1 Diabetes: A Consensus Report of the American Association of Clinical Endocrinologists, the American Association of Diabetes Educators, the American Diabetes Association, the Endocrine Society, JDRF International, The Leona M. and Harry B. Helmsley Charitable Trust, the Pediatric Endocrine Society, and the T1D Exchange

OBJECTIVE

To identify and define clinically meaningful type 1 diabetes outcomes beyond hemoglobin A1c (HbA1c) based upon a review of the evidence, consensus from clinical experts, and input from researchers, people with type 1 diabetes, and industry. Priority outcomes include hypoglycemia, hyperglycemia, time in range, diabetic ketoacidosis (DKA), and patient-reported outcomes (PROs). While priority outcomes for type 1 and type 2 diabetes may overlap, type 1 diabetes was the focus of this work.

RESEARCH AND METHODS

A Steering Committee-comprising representatives from the American Association of Clinical Endocrinologists, the American Association of Diabetes Educators, the American Diabetes Association, the Endocrine Society, JDRF International, The Leona M. and Harry B. Helmsley Charitable Trust, the Pediatric Endocrine Society, and the T1D Exchange-was the decision-making body for the Type 1 Diabetes Outcomes Program. Their work was informed by input from researchers, industry, and people with diabetes through Advisory Committees representing each stakeholder group. Stakeholder surveys were used to identify priority outcomes. The outcomes prioritized in the surveys were hypoglycemia, hyperglycemia, time in range, DKA, and PROs. To develop consensus on the definitions of these outcomes, the Steering Committee relied on published evidence, their clinical expertise, and feedback from the Advisory Committees.

RESULTS

The Steering Committee developed definitions for hypoglycemia, hyperglycemia, time in range, and DKA in type 1 diabetes. The definitions reflect their assessment of the outcome's short- and long-term clinical impact on people with type 1 diabetes. Knowledge gaps to be addressed by future research were identified. The Steering Committee discussed PROs and concluded that further type 1 diabetes-specific development is needed.

CONCLUSIONS

The Steering Committee recommends use of the defined clinically meaningful outcomes beyond HbA1c in the research, development, and evaluation of type 1 diabetes therapies.

Effect of verbal task complexity in a working memory paradigm in patients with type 1 diabetes. A fMRI study

Type 1 diabetes (T1D) is commonly diagnosed in childhood and adolescence, and the developing brain has to cope with its deleterious effects. Although brain adaptation to the disease may not result in evident cognitive dysfunction, the effects of T1D on neurodevelopment could alter the pattern of BOLD fMRI activation. The aim of this study was to explore the neural BOLD activation pattern in patients with T1D versus that of healthy matched controls while performing two visuospatial working memory tasks, which included a pair of assignments administered through a block design. In the first task (condition A), the subjects were shown a trial sequence of 3 or 4 white squares positioned pseudorandomly around a fixation point on a black background. After a fixed delay, a second corresponding sequence of 3 or 4 red squares was shown that either resembled (direct, 50%) or differed from (50%) the previous stimulation order. The subjects were required to press one button if the two spatial sequences were identical or a second button if they were not. In condition B, the participants had to determine whether the second sequence of red squares appeared in inverse order (inverse, 50%) or not (50%) and respond by pressing a button. If the latter sequence followed an order distinct from the inverse sequence, the subjects were instructed to press a different button. Sixteen patients with normal IQ and without diabetes complications and 16 healthy control subjects participated in the study. In the behavioral analysis, there were no significant differences between the groups in the pure visuo-spatial task, but the patients with diabetes exhibited poorer performance in the task with verbal stimuli (p < .001). However, fMRI analyses revealed that the patients with T1D showed significantly increased activation in the prefrontal inferior cortex, subcortical regions and the cerebellum (in general p < .001). These different activation patterns could be due to adaptive compensation mechanisms that are devoted to improving efficiency while solving more complex cognitive tasks.

The role of executive control in resolving grammatical number conflict in sentence comprehension

In sentences with a complex subject noun phrase, like "The key to the cabinets is lost", the grammatical number of the head noun (key) may be the same or different from that of the modifier noun phrase (cabinets). When the number is the same, comprehension is usually easier than when it is different. Grammatical number computation may occur while processing the modifier noun (integration phase) or while processing the verb (checking phase). We investigated at which phase number conflict and plausibility of the modifier noun as subject for the verb affect processing, and we imposed a gaze-contingent tone discrimination task in either phase to test whether number computation involves executive control. At both phases, gaze durations were longer when a concurrent tone task was present. Additionally, at the integration phase, gaze durations were longer under number conflict, and this effect was enhanced by the presence of a tone task, whereas no effects of plausibility of the modifier were observed. The finding that the effect of number match was larger under load shows that computation of the grammatical number of the complex noun phrase requires executive control in the integration phase, but not in the checking phase.

Luteolin as an anti-inflammatory and neuroprotective agent: A brief review

According to the World Health Organization, two billion people will be aged 60 years or older by 2050. Aging is a major risk factor for a number of neurodegenerative disorders. These age-related disorders currently represent one of the most important and challenging health problems worldwide. Therefore, much attention has been directed towards the design and development of neuroprotective agents derived from natural sources. These phytochemicals have demonstrated high efficacy and low adverse effects in multiple in vitro and in vivo studies. Among these phytochemicals, dietary flavonoids are an important and common chemical class of bioactive products, found in several fruits and vegetables. Luteolin is an important flavone, which is found in several plant products, including broccoli, pepper, thyme, and celery. Numerous studies have shown that luteolin possesses beneficial neuroprotective effects both in vitro and in vivo. Despite this, an overview of the neuroprotective effects of luteolin has not yet been accomplished. Therefore, the aim of this paper is to provide a review of the available literature regarding the neuroprotective effects of luteolin and its molecular mechanisms of action. Herein, we also review the available literature regarding the chemistry of luteolin, its herbal sources, and bioavailability as a pharmacological agent for the treatment and management of age-related neurodegenerative disorders.