Trajectories in glycemic control over time are associated with cognitive performance in elderly subjects with type 2 diabetes

The level of serum retinol-binding protein is associated with diabetic mild cognitive impairment

BACKGROUND

Several studies have shown that retinol-binding protein (RBP) is linked to diabetes and neurodegenerative diseases. However, no studies have elucidated the relationship between RBP and diabetic cognitive disorders.

OBJECTIVE

To determine whether the change characteristics of serum RBP are associated with alterations in cognitive functioning in type 2 diabetes mellitus (T2DM).

METHODS

In this study, 252 patients with T2DM and 34 people as healthy controls were included. According to the Montreal Cognitive Assessment (MoCA), the diabetic subjects were divided into the mild cognitive impairment (MCI) group and the Non-MCI group. Demographic characteristics and clinical indicators as well as serum RBP levels were analyzed.

RESULTS

The serum RBP levels in the MCI group were lower compared with the Non-MCI group (P = 0.02). The level of RBP was higher in the diabetes without MCI group than in the healthy control (P < 0.001). Serum RBP levels were positively correlated with MoCA scores (r = 0.178, P = 0.003). Binary Logistic regression model analysis showed that low RBP [odds ratio (OR) = 0.936], old age (OR = 1.074), high fasting blood glucose (OR = 1.164), and low fasting C-peptide (OR = 0.722) may be independent risk factors for diabetic MCI. The ROC curve of serum RBP for predicting diabetic MCI showed that the area under the curve was 0.630.

CONCLUSIONS

Our study revealed an association between serum RBP and diabetic MCI. Serum RBP levels in diabetic MCI are lower and correlated with cognitive function.

Association of long-term hyperglycaemia and insulin resistance with brain atrophy and cognitive decline: A longitudinal cohort study

AIM

To investigate the longitudinal changes in brain volume and cognitive function associated with diabetes at midlife, and to examine whether long-term hyperglycaemia, insulin resistance or secretory function is associated with brain atrophy and cognitive decline.

MATERIALS AND METHODS

We used data from 2377 participants with both baseline and 4-year follow-up brain magnetic resonance images and neuropsychological measures from the Ansan cohort of the Korean Genome Epidemiology Study. Time-weighted mean glycaemic values were calculated using all measurements over an average duration of 10.6 years from cohort initiation to baseline visits.

RESULTS

Type 2 diabetes was associated with greater white matter volume reduction (adjusted volume difference = -1.96 ml, 95% CI: -3.73, -0.18) and executive function decline (adjusted Z score difference = -0.14, 95% CI: -0.23, -0.05) during the follow-up period of 4.2 years. Decline of verbal and visual memory or verbal fluency was not associated with diabetes. Greater executive function decline was associated with higher time-weighted mean HbA1c level over the preceding 10.6 years (P < .001), but not with insulin resistance markers in the diabetes group. Participants with diabetes, whose time-weighted average HbA1c level was maintained above 6.5% over the previous decade, showed greater decline in executive function and global cognition than the normal glucose group.

CONCLUSIONS

Long-term hyperglycaemia was a major independent factor associated with rapid cognitive decline in middle-aged adults with diabetes. Maintaining ideal glucose levels in diabetes at midlife might prevent later rapid cognitive decline.

Data-Driven Identification of Long-Term Glycemia Clusters and Their Individualized Predictors in Finnish Patients with Type 2 Diabetes

Purpose

To gain an understanding of the heterogeneous group of type 2 diabetes (T2D) patients, we aimed to identify patients with the homogenous long-term HbA1c trajectories and to predict the trajectory membership for each patient using explainable machine learning methods and different clinical-, treatment-, and socio-economic-related predictors.

Patients and Methods

Electronic health records data covering primary and specialized healthcare on 9631 patients having T2D diagnosis were extracted from the North Karelia region, Finland. Six-year HbA1c trajectories were examined with growth mixture models. Linear discriminant analysis and neural networks were applied to predict the trajectory membership individually.

Results

Three HbA1c trajectories were distinguished over six years: "stable, adequate" (86.5%), "improving, but inadequate" (7.3%), and "fluctuating, inadequate" (6.2%) glycemic control. Prior glucose levels, duration of T2D, use of insulin only, use of insulin together with some oral antidiabetic medications, and use of only metformin were the most important predictors for the long-term treatment balance. The prediction model had a balanced accuracy of 85% and a receiving operating characteristic area under the curve of 91%, indicating high performance. Moreover, the results based on SHAP (Shapley additive explanations) values show that it is possible to explain the outcomes of machine learning methods at the population and individual levels.

Conclusion

Heterogeneity in long-term glycemic control can be predicted with confidence by utilizing information from previous HbA1c levels, fasting plasma glucose, duration of T2D, and use of antidiabetic medications. In future, the expected development of HbA1c could be predicted based on the patient's unique risk factors offering a practical tool for clinicians to support treatment planning.

Data-driven long-term glycaemic control trajectories and their associated health and economic outcomes in Finnish patients with incident type 2 diabetes

Background

Treatments should be customized to patients to improve patients’ health outcomes and maximize the treatment benefits. We aimed to identify meaningful data-driven trajectories of incident type 2 diabetes patients with similarities in glycated haemoglobin (HbA1c) patterns since diagnosis and to examine their clinical and economic relevance.

Materials and methods

A cohort of 1540 patients diagnosed in 2011–2012 was retrieved from electronic health records covering primary and specialized healthcare in the North Karelia region, Finland. EHRs data were compiled with medication purchase data. Average HbA1c levels, use of medications, and incidence of micro- and macrovascular complications and deaths were measured annually for seven years since T2D diagnosis. Trajectories were identified applying latent class growth models. Differences in 4-year cumulative healthcare costs with 95% confidence intervals (CIs) were estimated with non-parametric bootstrapping.

Results

Four distinct trajectories of HbA1c development during 7 years after T2D diagnosis were extracted: patients with “Stable, adequate” (66.1%), “Slowly deteriorating” (24.3%), and “Rapidly deteriorating” glycaemic control (6.2%) as well as “Late diagnosed” patients (3.4%). During the same period, 2.2 (95% CI 1.9–2.6) deaths per 100 person-years occurred in the “Stable, adequate” trajectory increasing to 3.2 (2.4–4.0) in the “Slowly deteriorating”, 4.7 (3.1–6.9) in the “Rapidly deteriorating” and 5.2 (2.9–8.7) in the “Late diagnosed” trajectory. Similarly, 3.5 (95% CI 3.0–4.0) micro- and macrovascular complications per 100 person-years occurred in the “Stable, adequate” trajectory increasing to 5.1 (4.1–6.2) in the “Slowly deteriorating”, 5.5 (3.6–8.1) in the “Rapidly deteriorating” and 7.3 (4.3–11.8) in the “Late diagnosed” trajectory. Patients in the “Stable, adequate” trajectory had lower accumulated 4-year medication costs than other patients.

Conclusions

Data-driven patient trajectories have clinical and economic relevance and could be utilized as a step towards personalized medicine instead of the common “one-fits-for-all” treatment practices.

Diagnostic, Prognostic, and Mechanistic Biomarkers of Diabetes Mellitus-Associated Cognitive Decline

Cognitive dysfunctions such as mild cognitive impairment (MCI), Alzheimer’s disease (AD), and other forms of dementia are recognized as common comorbidities of type 2 diabetes mellitus (T2DM). Currently, there are no disease-modifying therapies or definitive clinical diagnostic and prognostic tools for dementia, and the mechanisms underpinning the link between T2DM and cognitive dysfunction remain equivocal. Some of the suggested pathophysiological mechanisms underlying cognitive decline in diabetes patients include hyperglycemia, insulin resistance and altered insulin signaling, neuroinflammation, cerebral microvascular injury, and buildup of cerebral amyloid and tau proteins. Given the skyrocketing global rates of diabetes and neurodegenerative disorders, there is an urgent need to discover novel biomarkers relevant to the co-morbidity of both conditions to guide future diagnostic approaches. This review aims to provide a comprehensive background of the potential risk factors, the identified biomarkers of diabetes-related cognitive decrements, and the underlying processes of diabetes-associated cognitive dysfunction. Aging, poor glycemic control, hypoglycemia and hyperglycemic episodes, depression, and vascular complications are associated with increased risk of dementia. Conclusive research studies that have attempted to find specific biomarkers are limited. However, the most frequent considerations in such investigations are related to C reactive protein, tau protein, brain-derived neurotrophic factor, advanced glycation end products, glycosylated hemoglobin, and adipokines.

Aberrant Brain Spontaneous Activity and Synchronization in Type 2 Diabetes Mellitus Subjects Without Mild Cognitive Impairment

Objective: We aimed to explore whether the percent amplitude of fluctuation (PerAF) measurement could provide supplementary information for amplitude of low-frequency fluctuation (ALFF) about spontaneous activity alteration in type 2 diabetes mellitus (T2DM) subjects without mild cognitive impairment (MCI). Then we further evaluated the synchronization through the method of functional connectivity (FC) to better demonstrate brain changes in a more comprehensive manner in T2DM. Methods: Thirty T2DM subjects without MCI and thirty well-matched healthy subjects were recruited in this study. Subjects' clinical data, neuropsychological test results, and resting-state functional magnetic resonance imaging (rs-fMRI) data were acquired. Voxel-based group difference comparisons between PerAF and ALFF were conducted. Then, seed-based FC between the recognized brain regions based on PerAF and ALFF and the rest of the whole brain was performed. Results: Compared with healthy group, T2DM group had significantly decreased PerAF in the bilateral middle occipital gyrus and the right calcarine, increased ALFF in the right orbital inferior frontal gyrus and decreased ALFF in the right calcarine. Seed-based FC analysis showed that the right middle occipital gyrus of T2DM subjects exhibited significantly decreased FC with the right caudate nucleus and right putamen. According to the partial correlation analyses, hemoglobin A1c (HbA1c) and immediate memory scores on the auditory verbal learning test (AVLT) were negatively correlated in the T2DM group. However, we found that total cholesterol was positively correlated with symbol digit test (SDT) scores. Conclusion: PerAF and ALFF may have different sensitivities in detecting the abnormal spontaneous brain activity in T2DM subjects. We suggest PerAF values may add supplementary information and indicate additional potential neuronal spontaneous activity in T2DM subjects without MCI, which may provide new insights into the neuroimaging mechanisms underlying early diabetes-associated cognitive decline.

Trajectories of glycemic control with clinical pharmacy specialist management of veterans with type 2 diabetes

BACKGROUND

Improved control of glycemic control likely lowers the risk of diabetes complications and clinical pharmacy specialist (CPS) services can improve glycemic control. Though the pattern of control may also matter in terms of outcomes.

OBJECTIVES

The objective of this study was to examine the longitudinal trajectories of HbA1c among a large population of Veterans with type 2 diabetes who received CPS-led diabetes management.

METHODS

This is an observational, multicenter cohort study of Veterans with type-2 diabetes managed by CPSs between 7/1/2013 and 7/1/2017 with baseline glycosylated hemoglobin (HbA1c) level ≥8%. Two years of HbA1c measurements were used to group patients into distinct patterns of HbA1c trajectories over time using group-based trajectory modeling. Characteristics associated with successful HbA1c trajectories and association of assigned trajectories with all-cause and diabetes-related hospitalizations were analyzed using logistic regression.

RESULTS

A total of 4119 Veterans were included and able to be successfully segmented into six distinct HbA1c trajectory groups over time: High Gradually Decreasing (n = 325, 7.9%), Moderate Early Decline (n = 1692, 41.1%), Large Early Decline (n = 231, 5.6%), Uncontrolled Stable (n = 1468, 35.6%), Early Decline/Subsequent Increase (n = 266, 6.5%), and Very Uncontrolled Stable (n = 137, 3.3%). The distinguishing factor between successful and less successful trajectories appears to be the progress made within the first six months of pharmacist management.

CONCLUSIONS

Significant variability exists in the pattern of glycemic control over time of type 2 diabetes patients managed by clinical pharmacy specialists. Limited resources should be first prioritized to managing patients with very elevated HbA1c and into the first six months of CPS management.

The Relationship Between Glucose Control and Cognitive Function in People With Diabetes After a Lacunar Stroke

CONTEXT

Lacunar strokes and diabetes are risk factors for cognitive dysfunction. Elucidating modifiable risk factors for cognitive dysfunction has great public health implications. One factor may be glycemic status, as measured by glycated hemoglobin (A1c).

OBJECTIVE

The aim of this study was to assess the relationship between A1c and cognitive function in lacunar stroke patients with diabetes.

METHODS

The effect of baseline and follow-up A1c on the baseline and the change in Cognitive Assessment Screening Instrument (CASI) score over time among participants with a median of 2 cognitive assessments (range, 1-5) was examined in 942 individuals with diabetes and a lacunar stroke who participated in the Secondary Prevention of Small Subcortical Strokes (SPS3) trial (ClinicalTrials.gov No. NCT00059306).

RESULTS

Every 1% higher baseline A1c was associated with a 0.06 lower standardized CASI z score (95% CI, -0.101 to -0.018). Higher baseline A1c values were associated with lower CASI z scores over time (P for interaction = .037). A 1% increase in A1c over time corresponded with a CASI score decrease of 0.021 (95% CI, -0.0043 to -0.038) during follow-up. All these remained statistically significant after adjustment for age, sex, education, race, depression, hypertension, hyperlipidemia, body mass index, cardiovascular disease, obstructive sleep apnea, diabetic retinopathy, nephropathy insulin use, and white-matter abnormalities.

CONCLUSION

This analysis of lacunar stroke patients with diabetes demonstrates a relationship between A1c and change in cognitive scores over time. Intervention studies are needed to delineate whether better glucose control could slow the rate of cognitive decline in this high-risk population.

Population segmentation of type 2 diabetes mellitus patients and its clinical applications - a scoping review

Background

Population segmentation permits the division of a heterogeneous population into relatively homogenous subgroups. This scoping review aims to summarize the clinical applications of data driven and expert driven population segmentation among Type 2 diabetes mellitus (T2DM) patients.

Methods

The literature search was conducted in Medline®, Embase®, Scopus® and PsycInfo®. Articles which utilized expert-based or data-driven population segmentation methodologies for evaluation of outcomes among T2DM patients were included. Population segmentation variables were grouped into five domains (socio-demographic, diabetes related, non-diabetes medical related, psychiatric / psychological and health system related variables). A framework for PopulAtion Segmentation Study design for T2DM patients (PASS-T2DM) was proposed.

Results

Of 155,124 articles screened, 148 articles were included. Expert driven population segmentation approach was most commonly used, of which judgemental splitting was the main strategy employed (n = 111, 75.0%). Cluster based analyses (n = 37, 25.0%) was the main data driven population segmentation strategies utilized. Socio-demographic (n = 66, 44.6%), diabetes related (n = 54, 36.5%) and non-diabetes medical related (n = 18, 12.2%) were the most used domains. Specifically, patients’ race, age, Hba1c related parameters and depression / anxiety related variables were most frequently used. Health grouping/profiling (n = 71, 48%), assessment of diabetes related complications (n = 57, 38.5%) and non-diabetes metabolic derangements (n = 42, 28.4%) were the most frequent population segmentation objectives of the studies.

Conclusions

Population segmentation has a wide range of clinical applications for evaluating clinical outcomes among T2DM patients. More studies are required to identify the optimal set of population segmentation framework for T2DM patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12874-021-01209-w.

Glucose-Dementia Association Is Consistent Over Blood Pressure/Antihypertensive Groups

BACKGROUND

Higher glucose levels are associated with dementia risk in people with and without diabetes. However, little is known about how this association might vary by hypertension status and antihypertensive treatment. Most studies on modifiable dementia risk factors consider each factor in isolation.

OBJECTIVE

To test the hypothesis that hypertension and antihypertensive treatments may modify associations between glucose levels and dementia.

METHODS

Analyses of data generated from a research study and clinical care of participants from a prospective cohort of dementia-free older adults, including glucose measures, diabetes and antihypertensive treatments, and blood pressure data. We defined groups based on blood pressure (hypertensive versus not, ≥140/90 mmHg versus <140/90 mmHg) and antihypertensive treatment intensity (0, 1, or ≥2 classes of antihypertensives). We used Bayesian joint models to jointly model longitudinal exposure and time to event data.

RESULTS

A total of 3,056 participants without diabetes treatment and 480 with diabetes treatment were included (mean age at baseline, 75.1 years; mean 7.5 years of follow-up). Higher glucose levels were associated with greater dementia risk among people without and with treated diabetes. Hazard ratios for dementia were similar across all blood pressure/antihypertensive treatment groups (omnibus p = 0.82 for people without and p = 0.59 for people with treated diabetes).

CONCLUSION

Hypertension and antihypertensive treatments do not appear to affect the association between glucose and dementia risk in this population-based longitudinal cohort study of community-dwelling older adults. Future studies are needed to examine this question in midlife and by specific antihypertensive treatments.

Barriers to Diabetes Self-Management in a Subset of New Zealand Adults with Type 2 Diabetes and Poor Glycaemic Control

BACKGROUND

Despite the fact that there is an increasingly effective armoury of medications to treat diabetes, many people continue to have substantially elevated blood glucose levels. The purpose of this study was to explore what the barriers to diabetes management are in a cohort of people with diabetes and poor glycaemic control.

METHODS

Qualitative semistructured interviews were carried out with 10 people with diabetes who had known diabetes and a recent HbA1c of >11.3% (100 mmol/mol) to explore their experiences of barriers to diabetes self-management and glycaemic control.

RESULTS

Barriers to diabetes management were based around two key themes: biopsychosocial factors and knowledge about diabetes. Specifically, financial concerns, social stigma, medication side effects, and cognitive impairment due to hyperglycaemia were commonly reported as barriers to medication use. Other barriers included a lack of knowledge about their own condition, poor relationships with healthcare professionals, and a lack of relevant resources to support diet and weight loss.

CONCLUSION

People with diabetes with poor glycaemic control experience many of the same barriers as those reported elsewhere, but also experience issues specifically related to their severe hyperglycaemia. Management of diabetes could be improved via the increased use of patient education and availability of locally relevant resources.

Randomized Clinical Trial Examining the Impact of Lactobacillus rhamnosus GG Probiotic Supplementation on Cognitive Functioning in Middle-aged and Older Adults

PURPOSE

The gut microbiome has been linked to cognitive function and appears to worsen with aging. Probiotic supplementation has been found to improve the health of the gut microbiome. As such, it is possible that probiotic supplementation may protect the aging brain. The current study examined the cognitive benefits of probiotic supplementation (Lactobacillus rhamnosus GG) in healthy middle-aged and older adults.

MATERIALS AND METHODS

The study was a double-blind, placebo-controlled, randomized clinical trial. Two hundred community-dwelling adults aged 52-75 were enrolled (mean age=64.3, SD=5.52). A three-month intervention involved daily consumption of probiotic or placebo. Independent sample t-tests, chi-squared tests, and repeated measure ANOVAs compared groups and examined changes over time. Primary outcome was change in NIH Toolbox Total Cognition Score from baseline to follow-up.

RESULTS

A total of 145 participants were examined in primary analyses (probiotic=77, placebo=68) and excluded persons due to discontinuation, low adherence, missing data, or outlier values. Established criteria (ie ≥1 subtest t-scores ≤35; n=19, n=23) were used to operationally define cognitive impairment. Repeated measures ANOVAs revealed that persons with cognitive impairment who consumed probiotics exhibited a greater total cognition score improvement than persons with cognitive impairment in the placebo group and cognitively intact persons in probiotic or placebo groups.

CONCLUSION

Lactobacillus rhamnosus GG probiotic supplementation was associated with improved cognitive performance in middle-aged and older adults with cognitive impairment. Probiotic supplementation may be a novel method for protecting cognitive health in aging.

Long-term trajectories of BMI predict carotid stiffness and plaque volume in type 2 diabetes older adults: a cohort study

BACKGROUND

High body mass index (BMI) is a risk factor for type 2 diabetes and cardiovascular disease. However, its relationships with indices of carotid stiffness and plaque volume are unclear. We investigated associations of long-term measurements of BMI with indices of carotid stiffness and atherosclerosis among non-demented diabetes patients from the Israel Diabetes and Cognitive Decline (IDCD) study.

METHODS

Carotid ultrasound indices [carotid intima media thickness (cIMT), distensibility, elastography and plaque volume] were assessed in N = 471 participants. Mean BMI across all MHS diabetes registry measurements and trajectories of BMI were calculated. BMI was categorized into three trajectory groups representing: a relatively stable normal weight (n = 185, 44%), overweight trajectory (n = 188, 44.8%) and a trajectory of obesity (n = 47, 11.2%). Linear and logistic regressions estimated associations of carotid indices with mean BMI and BMI trajectories.

RESULTS

Compared to the normal weight trajectory, an obesity trajectory was associated with carotid distensibility (β = - 3.078, p = 0.037), cIMT (β = 0.095, p = 0.004), and carotid elastography (β = 0.181, p = 0.004) but not with plaque volume (β = 0.066, p = 0.858). Compared with the normal weight trajectory, an obesity trajectory was associated with increased odds for impaired carotid distensibility (OR = 2.790, p = 0.033), impaired cIMT (OR = 5.277, p = 0.001) and large carotid plaque volume (OR = 8.456, p = 0.013) but not with carotid elastography (OR = 1.956, p = 0.140). Mean BMI was linearly associated with Distensibility (β = - 0.275, p = 0.005) and cIMT (β = 0.005, p = 0.026).

CONCLUSIONS

Long-term measurements of adiposity are associated with indices of carotid stiffness and plaque volume among older type 2 diabetes adults.

Time in suboptimal glycemic control over 10 years for patients newly diagnosed with type 2 diabetes

OBJECTIVE

To estimate time in suboptimal glycemic control among patients with incident type 2 diabetes (T2D) over 10 years.

METHODS

We calculated percent of time in suboptimal glycemic control using three A1C thresholds (8%, 7.5%, 7%) following T2D diagnosis. Stratified analyses were conducted based on age and A1C levels at T2D diagnosis.

RESULTS

We identified 28,315 patients with incident T2D. Percent of time in suboptimal glycemic control increased with T2D duration. Mean percent time in suboptimal A1C control in the first 2 years following diagnosis was 30%, 34% and 40% for the 8%, 7.5%, and 7% thresholds, respectively. In the 6-10 years following T2D diagnosis, the percent time in suboptimal A1C control increased to 39%, 48% and 61%, for the 8%, 7.5%, and 7% thresholds, respectively. Time in suboptimal glycemic control was longer among younger patients aged 20-44 versus ≥65 years and those with higher A1C (>8%) versus lower A1C (<7%) at diagnosis.

CONCLUSIONS

Over 10 years following diagnosis, T2D patients spent one-third to over one-half of their time in suboptimal glycemic control. Reducing time spent above desired A1C targets could lower risk of microvascular and macrovascular complications.

Trajectories of glycaemia following acute pancreatitis: a prospective longitudinal cohort study with 24 months follow-up

BACKGROUND

New-onset diabetes is the most common sequela of acute pancreatitis (AP). Yet, prospective changes in glycaemia over time have never been investigated comprehensively in this study population. The primary aim was to determine the cumulative incidence of new-onset prediabetes and new-onset diabetes after AP over 24 months of follow-up in a prospective cohort study. The secondary aim was to identify trajectories of glycaemia during follow-up and their predictors at the time of hospitalisation.

METHODS

Patients with a prospective diagnosis of AP and no diabetes based on the American Diabetes Association criteria were followed up every 6 months up to 24 months after hospital discharge. Incidence of new-onset prediabetes/diabetes over each follow-up period was calculated. Group-based trajectory modelling was used to identify common changes in glycaemia. Multinomial regression analyses were conducted to investigate the associations between a wide array of routinely available demographic, anthropometric, laboratory, imaging, and clinical factors and membership in the trajectory groups.

RESULTS

A total of 152 patients without diabetes were followed up. The cumulative incidence of new-onset prediabetes and diabetes was 20% at 6 months after hospitalisation and 43% over 24 months of follow-up (p trend < 0.001). Three discrete trajectories of glycaemia were identified: normal-stable glycaemia (32%), moderate-stable glycaemia (60%), and high-increasing glycaemia (8%). Waist circumference was a significant predictor of moderate-stable glycaemia. None of the studied predictors were significantly associated with high-increasing glycaemia.

CONCLUSIONS

This first prospective cohort study of changes in glycaemia (determined at structured time points in unselected AP patients) showed that at least one out of five patients develops new-onset prediabetes or diabetes at 6 months of follow-up and more than four out of ten-in the first 2 years. Changes in glycaemia after AP follow three discrete trajectories. This may inform prevention or early detection of critical changes in blood glucose metabolism following an attack of AP and, hence, reduce the burden of new-onset diabetes after acute pancreatitis.

Diabetes-Related Topics in an Online Forum for Caregivers of Individuals Living With Alzheimer Disease and Related Dementias: Qualitative Inquiry

BACKGROUND

Diabetes and Alzheimer disease and related dementias (ADRD) are the seventh and sixth leading causes of death in the United States, respectively, and they coexist in many older adults. Caring for a loved one with both ADRD and diabetes is challenging and burdensome.

OBJECTIVE

This study aims to explore diabetes-related topics in the Alzheimer's Association ALZConnected caregiver forum by family caregivers of persons living with ADRD.

METHODS

User posts on the Alzheimer's Association ALZConnected caregiver forum were extracted. A total of 528 posts related to diabetes were included in the analysis. Of the users who generated the 528 posts, approximately 96.1% (275/286) were relatives of the care recipient with ADRD (eg, child, grandchild, spouse, sibling, or unspecified relative). Two researchers analyzed the data independently using thematic analysis. Any divergence was discussed among the research team, and an agreement was reached with a senior researcher's input as deemed necessary.

RESULTS

Thematic analysis revealed 7 key themes. The results showed that comorbidities of ADRD were common topics of discussions among family caregivers. Diabetes management in ADRD challenged family caregivers. Family caregivers might neglect their own health care because of the caring burden, and they reported poor health outcomes and reduced quality of life. The online forum provided a platform for family caregivers to seek support in their attempts to learn more about how to manage the ADRD of their care recipients and seek support for managing their own lives as caregivers.

CONCLUSIONS

The ALZConnected forum provided a platform for caregivers to seek informational and emotional support for caring for persons living with ADRD and diabetes. The overwhelming burdens with these two health conditions were apparent for both caregivers and care recipients based on discussions from the online forum. Studies are urgently needed to provide practical guidelines and interventions for diabetes management in individuals with diabetes and ADRD. Future studies to explore delivering diabetes management interventions through online communities in caregivers and their care recipients with ADRD and diabetes are warranted.

Triad of impairment in older people with diabetes-reciprocal relations and clinical implications

Frailty is emerging as a new category complication of diabetes in older people. Clinically, frailty is still not well defined and mostly viewed as a decline in solely the physical domain. However, frailty is a multidimensional syndrome and the newly introduced concept of "triad of impairment" (physical, cognitive and emotional) may be a more representative of the broad nature of frailty. The components of the triad of impairment (TOI) commonly coexist and demonstrate a reciprocal relation. Diabetes in old age appears to increase the risk of the triad of impairment, which may eventually progress to disability. Therefore, older people with diabetes should be regularly assessed for the presence of these three key components. Adequate nutrition and regular resistance exercise training have been shown to have a positive impact on the long-term outcome in this population. However, the role of good glycaemic control and the use of current hypoglycaemic medications in reducing the incidence of this triad are less clear. Future research is needed to develop novel hypoglycaemic medications that not only focus on glycaemic control and cardiovascular safety but also on reducing the risk of the triad of impairment.

Predictors of glycemic control after decline of insulin therapy by patients with type 2 diabetes

AIM

Decline of insulin therapy by patients is common but poorly investigated. We conducted this study to determine patient and treatment characteristics predictive of glycemic control after declining clinician recommendation to initiate insulin therapy.

METHODS

We retrospectively studied adults with type 2 diabetes mellitus treated at two academic medical centers between 1993 and 2014 who declined their healthcare provider recommendation to initiate insulin.

RESULTS

In a multivariable analysis of 300 study patients adjusted for demographics, comorbidities and clustering within providers, higher baseline HbA1c (OR 1.85; 95% CI 1.40 to 2.39; p < 0.001) and lifestyle changes (OR 8.39; 95% CI 3.26 to 21.55; p < 0.001) were associated with greater, while non-adherence to diabetes medications (OR 0.014; 95% CI 0.0025 to 0.085; p < 0.001) and discontinuation of a non-insulin diabetes medication (OR 0.30; 95% CI 0.11 to 0.80; p = 0.016) were associated with lower probability of HbA1c decrease after declining insulin therapy.

CONCLUSION

We identified patient characteristics and treatment strategies associated with success and failure of glycemic control after insulin therapy decline by the patient. This information can assist in selection of optimal therapeutic approaches for these individuals.

Time-dependent impairments in learning and memory in Streptozotocin-induced hyperglycemic rats

The sedentary lifestyle is responsible for the high prevalence of diabetes which also impairs cognition including learning and memory. Various studies have highlighted the learning and memory impairments in rodent models but data regarding the timeline of their development and their correlation to biochemical parameters are scarce. So, the present study was designed to investigate the type of memory which is more susceptible to hyperglycemia and its correlation with biochemical parameters such as inflammatory cytokines, cAMP response element binding (CREB) and protein kinase B (Akt) activation. Hyperglycemia was induced using streptozotocin (STZ, 45 mg/kg i.p.) and confirmed by measuring fasting blood glucose levels after 1 week of STZ injection. Learning and memory deficits were evaluated using the Novel Object Recognition Test (NORT) and Morris water maze (MWM), and correlated with biochemical parameters (TNF-α, IL-1β, and dopamine) at 3, 6 and 9 weeks. STZ-injected rats after 3 weeks of injection demonstrated moderate hyperglycemia (blood glucose = 7.99 ± 0.62 mM) with intact learning and reference memory; however, their working memory was impaired in MWM. Severe hyperglycemia (blood glucose = 11.51 ± 0.69 mM) accompanied by impaired short, long, and working memory was evident after 6 weeks whereas learning was intact. After 9 weeks of STZ injection, hyperglycemia was more pronounced (13.69 ± 1.43 mM) and accompanied by a learning deficit in addition to short, long, and working memory impairments. The extent of hyperglycemia either in terms of duration or severity resulted in enhanced inflammation, down-regulation of the level of dopamine, protein expression of AKT and CREB, which possibly affected learning and memory negatively.

Fasting plasma glucose in young adults free of diabetes is associated with cognitive function in midlife

Background

Evidence for an association of fasting plasma glucose (FPG) with cognitive function in adults free of diabetes is scarce and based on middle-aged and older adults. We examined the association of FPG, measured at age 30, and of change in FPG from age 30 to 43, with cognitive function at age 50.

Methods

505 nondiabetic participants of the population-based Jerusalem Lipid Research Clinic (LRC) cohort study had baseline FPG, 2-h post-oral challenge plasma glucose (OGTT) and insulin determined at ages 28-32, and FPG and OGTT again at ages 41-46. Subsequently at ages 48-52, global cognitive function and its five specific component domains were assessed with a NeuroTrax computerized test battery, using multiple linear regression and multivariable logistic models.

Results

Hyperglycemia (FPG ≥ 5.6 mmol/l vs. <5.6 mmol/l) at baseline was associated with poorer global cognitive function in midlife (predominantly in the visual spatial and attention domains), independent of socio-demographic characteristics, life style variables, body mass index (BMI), and inflammatory and biochemical variables (standardized Beta = -0.121, P = 0.002, plinear trend(FPG continuous) =0.016). Similarly, increased odds for low-ranked (lowest fifth) global cognition was evident (ORper mmol/l FPG=2.31, 95% CI = 1.30-4.13, P = 0.005). Baseline OGTT, insulin resistance (HOMA-IR) and change in FPG and OGTT over 13 years were not associated with cognition.

Conclusion

A higher FPG in young adults was associated with lower cognitive performance in midlife. Although we cannot dismiss the possibility of reverse causation, hyperglycemia at a young age may be a modifiable risk factor for low-ranked cognitive function in midlife.

Cognitive Frailty in Older People with Type 2 Diabetes Mellitus: the Central Role of Hypoglycaemia and the Need for Prevention

PURPOSE OF REVIEW

To highlight the central role of hypoglycaemia in the causation of cognitive frailty and explore ways of recognition and prevention of hypoglycaemia.

RECENT FINDINGS

Cognitive frailty is an emerging new concept defined as the concomitant presence of physical frailty and cognitive impairment. In older people with diabetes, cognitive frailty is associated with an increased risk of mortality greater than from either physical frailty or cognitive impairment alone. Hypoglycaemia is directly associated with increased risk of cognitive impairment and physical frailty which are the two components of cognitive frailty. The incidence of hypoglycaemia in older people with diabetes is rising and hypoglycaemia-related hospitalisation has overtaken that of hyperglycaemia. Recognition of hypoglycaemic episodes in old age remains challenging which leads to misdiagnoses and under-reporting. Therefore, hypoglycaemia prevention strategies are needed. Research is still required to investigate whether prevention of hypoglycaemia would lead to a reduction in the incidence of cognitive frailty.

Identifying Latent Subgroups of High-Risk Patients Using Risk Score Trajectories

OBJECTIVE

Many healthcare systems employ population-based risk scores to prospectively identify patients at high risk of poor outcomes, but it is unclear whether single point-in-time scores adequately represent future risk. We sought to identify and characterize latent subgroups of high-risk patients based on risk score trajectories.

STUDY DESIGN

Observational study of 7289 patients discharged from Veterans Health Administration (VA) hospitals during a 1-week period in November 2012 and categorized in the top 5th percentile of risk for hospitalization.

METHODS

Using VA administrative data, we calculated weekly risk scores using the validated Care Assessment Needs model, reflecting the predicted probability of hospitalization. We applied the non-parametric k-means algorithm to identify latent subgroups of patients based on the trajectory of patients' hospitalization probability over a 2-year period. We then compared baseline sociodemographic characteristics, comorbidities, health service use, and social instability markers between identified latent subgroups.

RESULTS

The best-fitting model identified two subgroups: moderately high and persistently high risk. The moderately high subgroup included 65% of patients and was characterized by moderate subgroup-level hospitalization probability decreasing from 0.22 to 0.10 between weeks 1 and 66, then remaining constant through the study end. The persistently high subgroup, comprising the remaining 35% of patients, had a subgroup-level probability increasing from 0.38 to 0.41 between weeks 1 and 52, and declining to 0.30 at study end. Persistently high-risk patients were older, had higher prevalence of social instability and comorbidities, and used more health services.

CONCLUSIONS

On average, one third of patients initially identified as high risk stayed at very high risk over a 2-year follow-up period, while risk for the other two thirds decreased to a moderately high level. This suggests that multiple approaches may be needed to address high-risk patient needs longitudinally or intermittently.

Patient clusters based on HbA1c trajectories: A step toward individualized medicine in type 2 diabetes

Aims

To identify clinically meaningful clusters of patients with similar glycated hemoglobin (HbA1c) trajectories among patients with type 2 diabetes.

Methods

A retrospective cohort study using unsupervised machine learning clustering methodologies to determine clusters of patients with similar longitudinal HbA1c trajectories. Stability of these clusters was assessed and supervised random forest analysis verified the clusters’ reproducibility. Clinical relevance of the clusters was assessed through multivariable analysis, comparing differences in risk for a composite outcome (macrovascular and microvascular outcomes, hypoglycemic events, and all-cause mortality) at HbA1c thresholds for each cluster.

Results

Among 60,423 patients, three clusters of HbA1c trajectories were generated: stable (n = 45,679), descending (n = 6,084), and ascending (n = 8,660) trends, which were reproduced with 99.8% accuracy using a random forest model. In the clinical relevance assessment, HbA1c levels demonstrated a J-shape association with the risk for outcomes. HbA1c level thresholds for minimizing outcomes’ risk differed by cluster: 6.0–6.4% for the stable cluster, <8.0% for the descending cluster, and <9.0 for the ascending cluster.

Conclusions

By applying unsupervised machine learning to longitudinal HbA1c trajectories, we have identified clusters of patients who have distinct risk for diabetes-related complications. These clusters can be the basis for developing individualized models to personalize glycemic targets.

A randomized clinical trial examining the impact of LGG probiotic supplementation on psychological status in middle-aged and older adults

Cognitive decline is common in older adults and more than 5 million Americans suffer from Alzheimer's disease (AD). A number of physiological processes including systemic inflammation, excess adiposity, and impaired glucoregulation arise from a combination of genetic and behavioral factors and increase risk for developing AD or other forms of dementia. Recent research suggests that the gut microbiome may moderate these pathological processes and possibly influence cognitive outcomes. This paper reviews the methodology for a double-blind, randomized clinical trial examining the influence of Lactobacillus GG (LGG) probiotic supplementation on mood and cognitive functioning in middle-aged and older adults. Our two primary hypotheses include: 1) Participants randomized to the probiotic group will show greater improvements in psychological status compared to participants in the placebo group; 2) Participants randomized to the probiotic group will show greater improvements in executive functioning and processing speed, as evidenced through performance on neuropsychological testing, than participants in the placebo group. We anticipate these results will inform future efforts on the feasibility of LGG probiotic supplementation as an intervention for psychological status and cognitive functioning and further elucidate the link between the gut microbiome and cognitive health.

Longitudinal trends in HbA1c patterns and association with outcomes: A systematic review

BACKGROUND

This study aimed to review studies that identified patterns of longitudinal HbA1c trends in patients with diabetes and to summarize factors and outcomes associated with distinct trajectory patterns.

METHODS

PubMed and Web of Science were systematically searched for studies examining HbA1c trends among patients with diabetes from database inception through September 2017. Articles were included if they met the following inclusion criteria: (a) longitudinal study of subjects with diabetes only, (b) use of serial measurements of HbA1c , and (c) analysis of the trend of HbA1c using group-based trajectory approaches.

RESULTS

Twenty studies were included, 11 on type 1 diabetes and 9 on type 2 diabetes. These studies identified 2 to 6 HbA1c trajectory patterns. The most commonly identified patterns included stable HbA1c around 7.0% and at levels between 8.0% and 9.9%, which usually captured the HbA1c pattern among the majority of subjects in the study population. Unstable patterns identified included increasing HbA1c trend, decreasing HbA1c trend, and non-linear patterns. These patterns were associated with differential risk of disease outcomes, over and beyond single-point HbA1c measures. Age, gender, ethnicity, diabetes duration, disease management frequency, cardiovascular risk factors, insulin treatment, family environment, and psychosocial factors were the most frequently reported factors associated with membership of specific HbA1c pattern groups.

CONCLUSION

Common patterns of longitudinal HbA1c trends were identified despite heterogeneity among the studies. A better understanding of what underlies these different patterns may provide opportunities to tailor therapies and care for these patients to reduce adverse outcomes.

The chicken or the egg? Does glycaemic control predict cognitive function or the other way around?

The association between type 2 diabetes and cognitive dysfunction is well established. Prevention of the development of type 2 diabetes and its complications, as well as cognitive dysfunction and dementia, are leading goals in these fields. Deciphering the causality direction of the interplay between type 2 diabetes and cognitive dysfunction, and understanding the timeline of disease progression, are crucial for developing efficient prevention strategies. The prevailing perception is that type 2 diabetes leads to cognitive dysfunction and dementia. There is substantial evidence showing that accelerated cognitive decline in type 2 diabetes starts in midlife (mean age 40-60 years) and that it may even begin at the prediabetes stage. However, in this issue of Diabetologia, Altschul et al (doi: https://doi.org/10.1007/s00125-018-4645-8 ) show evidence for the reverse causality hypothesis, i.e. that lower cognitive function precedes poor glycaemic control. They found that cognitive function at early adolescence (age 11 years) predicts both HbA_1c levels and cognitive function at age 70 years. Moreover, they found that lower cognitive function at age 70 is associated with an increase in HbA_1c from age 70 to 79 years. Based on these findings, future studies should explore whether developing prevention strategies that target young adolescents with lower cognitive function will result in prevention of type 2 diabetes, breaking the vicious cycle of type 2 diabetes and cognitive dysfunction.

Impact of glycemic status on longitudinal cognitive performance in men with and without HIV infection

OBJECTIVES

To determine the relationship between glycemic status and cognitive performance in men living with HIV (MLWH) and without HIV infection.

DESIGN

A prospective HIV/AIDS cohort study in four US cities between 1999 and 2016.

METHODS

Glycemic status was categorized as normal glucose, impaired fasting glucose, controlled diabetes mellitus and uncontrolled diabetes mellitus at each semiannual visit. Cognitive performance was evaluated using nine neuropsychological tests which measure attention, constructional ability, verbal learning, executive functioning, memory and psychomotor speed. Linear mixed models were used to assess the association between glycemic status and cognition.

RESULTS

Overall, 900 MLWH and 1149 men without HIV were included. MLWH had significantly more person-visits with impaired fasting glucose (52.1 vs. 47.9%) and controlled diabetes mellitus (58.2 vs. 41.8%) than men without HIV (P < 0.05). Compared with men with normal glucose, men with diabetes mellitus had significantly poorer performance on psychomotor speed, executive function and verbal learning (all P < 0.05). There was no difference in cognition by HIV serostatus. The largest effect was observed in individuals with uncontrolled diabetes mellitus throughout the study period, equivalent to 16.5 and 13.4 years of aging on psychomotor speed and executive function, respectively, the effect of which remained significant after adjusting for HIV-related risk factors. Lower CD4+ nadir was also associated with worse cognitive performance.

CONCLUSION

Abnormalities in glucose metabolism were more common among MLWH than men without HIV and were related to impaired cognitive performance. Metabolic status, along with advanced age and previous immunosuppression, may be important predictors of cognition in the modern antiretroviral therapy era.

Factors Associated With Short and Long Term Cognitive Changes in Patients With Sepsis

This study aimed to assess cognition in patients with severe sepsis or septic shock and whether cognitive impairment was associated with clinical and laboratory parameters. We conducted a cohort study of patients with severe sepsis and septic shock evaluated within 24 h and one year after ICU discharge. Demographic, clinical and laboratory data were analyzed, and the following neuropsychological tests were applied: Consortium to Establish Registry for Alzheimer’s Disease, Mini-Mental State Examination, and Trail Making Test forms A and B. We included 33 patients, mean age of 49, 19% were female. Patients underperformed on most measures 24 h after ICU discharge, with improvement on follow-up. IQCODE, APACHE II scores, NSE and IFN-γ levels at ICU discharge were associated with poor cognitive performance, while higher educational level was associated with good cognitive performance. The time to first antibiotic dose, accumulated dose of haloperidol during UCI stay and mean glycemia were also associated with poor cognitive outcome. In general, patients with severe sepsis or septic shock have cognitive impairment that can improve over time. This improvement was associated with factors identified during their ICU stay, such as cognitive reserve, educational level, mean glycemia during ICU stay and NSE level.

An Update on Type 2 Diabetes Mellitus as a Risk Factor for Dementia

With the rapidly expanding evidence on brain structural and functional changes in type 2 diabetes mellitus (T2DM) patients, there is an increasing need to update our understanding on how T2DM associates with dementia as well as the underlying pathophysiological mechanisms. A literature search of T2DM and dementia or cognition impairments was carried out in electronic databases Medline, EMBASE, and Google Scholar. In this review, the chosen evidence was limited to human subject studies only, and data on either type 1 diabetes mellitus (T1DM) or non-classified diabetes were excluded. T2DM is a risk factor for both vascular dementia (VaD) and Alzheimer's disease (AD), although AD pathological marker studies have not provided sufficient evidence. T2DM interacts additively or synergistically with many factors, including old age, hypertension, total cholesterol, and APOEɛ4 carrier status for impaired cognition functions seen in patients with T2DM. In addition, comorbid T2DM can worsen the clinical presentations of patients with either AD or VaD. In summary, T2DM increases the risk for AD through different mechanisms for VaD although some mechanisms may overlap. Tau-related neurofibrillary tangles instead of amyloid-β plaques are more likely to be the pathological biomarkers for T2DM-related dementia. Degeneration of neurons in the brain, impaired regional blood supply/metabolism, and genetic predisposition are all involved in T2DM-associated dementia or cognitive impairments.

Homeostatic effect of laughter on diabetic cardiovascular complications: The myth turned to fact

AIMS

Laughter has been used for centuries to alleviate pain in morbid conditions. It was not until 1976 that scientists thought about laughter as a form of therapy that can modulate hormonal and immunological parameters that affect the outcome of many serious diseases. Moreover, laughter therapy was shown to be beneficial in type 2 diabetes mellitus (T2DM) by delaying the onset of many diabetic complications. Laughter is also described to influence the cardiovascular and endothelial functions and thus may protect against diabetic cardiovascular complications. In this review, we outline the different biochemical, physiological and immunological mechanisms by which laughter may influence the overall state of wellbeing and enhance disease prognosis. We also focus on the biological link between laughter therapy and diabetic cardiovascular complications as well as the underlying mechanisms involved in T2DM.

METHODS

Reviewing all the essential databases for "laughter" and "type 2 diabetes mellitus".

RESULTS

Although laughter therapy is still poorly investigated, recent studies show that laughter may retard the onset of diabetic complications, enhance cardiovascular functions and rectify homeostatic abnormalities associated with T2DM.

CONCLUSIONS

Laughter therapy is effective in delaying diabetic complications and should be used as an adjuvant therapy.

Longitudinal trends in HbA1c and associations with comorbidity and all-cause mortality in Asian patients with type 2 diabetes: A cohort study

AIMS

This study examined longitudinal trends in HbA1c in a multi-ethnic Asian cohort of diabetes patients, and the associations of these trends with future risk of acute myocardial infarction (AMI), stroke, end stage renal failure (ESRD) and all-cause mortality.

METHODS

6079 participants with type 2 diabetes mellitus in Singapore were included. HbA1c measurements for the five years previous to recruitment were used to identify patterns of HbA1c trends. Outcomes were recorded through linkage with the National Disease Registry. The median follow-up for longitudinal trends in HbA1c was 4.1years and for outcomes was between 7.0 and 8.3years. HbA1c patterns were identified using latent class growth modeling, and associations with outcomes were analyzed using Cox proportional hazards models.

RESULTS

Four distinct HbA1c patterns were observed; "low-stable" (72·2%), "moderate-stable" (22·0%), "moderate-increase" (2·9%), and "high-decrease" (2·8%). The risk of comorbidities and death was significantly higher in moderate-increase and high-decrease groups compared to the low-stable group; the hazard ratios for stroke, ESRD, and death for moderate increase group were 3.22 (95%CI 1.27-8.15), 4.76 (95%CI 1.92-11.83), and 1.88 (95%CI 1.15-3.07), respectively, and for high-decrease group were 2.16 (95%CI 1.02-4.57), 3.05 (95%CI 1.54-6.07), and 2.79 (95%CI 1.97-3.95), respectively. Individuals in the moderate-increase group were significantly younger, with longer diabetes duration, and greater proportions of Malays and Indians.

CONCLUSIONS

Deteriorating HbA1c pattern and extremely high initial HbA1c are associated with increased risk of long-term comorbidities and death. Therapeutic interventions to alter longitudinal HbA1c trends may be helpful in reducing this risk.

The relationship between obesity and cognitive health and decline

The relationship between obesity and cognitive impairment is important given the globally ageing population in whom cognitive decline and neurodegenerative disorders will carry grave individual, societal and financial burdens. This review examines the evidence for the link between obesity and cognitive function in terms of both the immediate effects on cognitive performance, and effects on the trajectory of cognitive ageing and likelihood of dementia. In mid-life, there is a strong association between obesity and impaired cognitive function. Anthropometric measures of obesity are also associated with reduced neural integrity (e.g. grey and white matter atrophy). Increasing age coupled with the negative metabolic consequences of obesity (e.g. type 2 diabetes mellitus) are likely to significantly contribute to cognitive decline and incidence of dementia. Stress is identified as a potential risk factor promoting abdominal obesity and contributing to impaired cognitive function. However, the potentially protective effects of obesity against cognitive decline in older age require further examination. Finally, surgical and whole diet interventions, which address obesity may improve cognitive capacity and confer some protection against later cognitive decline. In conclusion, obesity and its comorbidities are associated with impaired cognitive performance, accelerated cognitive decline and neurodegenerative pathologies such as dementia in later life. Interventions targeting mid-life obesity may prove beneficial in reducing the cognitive risks associated with obesity.

Comparative Effectiveness for Glycemic Control in Older Adults with Diabetes

PURPOSE OF REVIEW

To review and summarize the current data for comparative effectiveness of glycemic control in older adults.

RECENT FINDINGS

In the last several years, professional societies have released guidelines for glycemic control in older adults, generally recommending individualized HbA1c goals. However, recent observational studies demonstrate that many older adults remain aggressively managed and are at increased risk of hypoglycemia. Large randomized trials of older adults with diabetes have failed to show cardiovascular benefit from intensive glycemic control and show only minimal microvascular benefit. Additionally, a few studies suggest that suboptimal glycemic control can increase the risk for geriatric syndromes. Emerging research suggests similar safety and efficacy of glucose-lowering therapies in older versus younger adults.

SUMMARY

Overall, there is a paucity of data supporting the benefit of intensive glycemic control in older adults. More research is needed in this vulnerable population.

Visit-to-Visit Variations in Fasting Plasma Glucose and HbA1c Associated With an Increased Risk of Alzheimer Disease: Taiwan Diabetes Study

OBJECTIVE

The relationship between glycemic variability and the incidence of Alzheimer disease (AD) in patients with type 2 diabetes mellitus (T2DM) is unclear. The aim of this study was to examine visit-to-visit variations in fasting plasma glucose (FPG) and glycated hemoglobin (HbA_1c) represented by the coefficient of variation (CV) and to determine whether they were independently associated with AD, irrespective of HbA_1c and other traditional risk factors in such patients.

RESEARCH DESIGN AND METHODS

Patients with T2DM enrolled in the National Diabetes Care Management Program, age ≥60 years, and without diagnosis of AD (n = 16,706) were included in the study. Potential risk factors were analyzed using extended Cox proportional hazards regression models for competing risk of mortality on AD incidence.

RESULTS

During a median follow-up of 8.88 years, 831 incident cases of AD were identified, with a crude incidence rate of 3.5/1,000 person-years. After adjustment for sociodemographic factors, lifestyle behaviors, diabetes-related variables, FPG and HbA_1c, drug-related variables, and comorbidities, both FPG CV and HbA_1c CV were found to be significant predictors of AD, with corresponding hazard ratios of 1.27 (95% CI 1.06-1.52) for the third tertile in FPG CV and 1.32 (95% CI 1.11-1.58) for the third tertile in HbA_1c CV.

CONCLUSIONS

FPG CV and HbA_1c CV are independently associated with AD. The associations between glycemic variability and AD demonstrated in this study suggest a linked pathophysiological mechanism, which is worthy of further investigation. Further research is required to confirm our results and to evaluate whether FPG CV and HbA_1c CV can be valuable therapeutic targets for patients with T2DM at risk.

The role of melatonin in the onset and progression of type 3 diabetes

Alzheimer’s disease (AD) is defined by the excessive accumulation of toxic peptides, such as beta amyloid (Aβ) plaques and intracellular neurofibrillary tangles (NFT). The risk factors associated with AD include genetic mutations, aging, insulin resistance, and oxidative stress. To date, several studies that have demonstrated an association between AD and diabetes have revealed that the common risk factors include insulin resistance, sleep disturbances, blood brain barrier (BBB) disruption, and altered glucose homeostasis. Many researchers have discovered that there are mechanisms common to both diabetes and AD. AD that results from insulin resistance in the brain is termed “type 3 diabetes”. Melatonin synthesized by the pineal gland is known to contribute to circadian rhythms, insulin resistance, protection of the BBB, and cell survival mechanisms. Here, we review the relationship between melatonin and type 3 diabetes, and suggest that melatonin might regulate the risk factors for type 3 diabetes. We suggest that melatonin is crucial for attenuating the onset of type 3 diabetes by intervening in Aβ accumulation, insulin resistance, glucose metabolism, and BBB permeability.

An alternative approach to modelling HbA1c trajectories in patients with type 2 diabetes mellitus

AIMS

Time-dependent HbA1c trajectories in health economic models of type 2 diabetes mellitus (T2DM) are typically informed by the UK Prospective Diabetes Study (UKPDS). However, this approach may not accurately predict HbA1c progression in patients who do not conform to the demographic profile of the original UKPDS cohort. This study aimed to develop an alternative mathematical model (MM) to simulate HbA1c progression in T2DM.

MATERIALS AND METHODS

A systematic literature review identified studies, published between 2005 and 2015, that reported HbA1c in adult T2DM patients over a minimum duration of 18 months. Pooled data from eligible studies were used to develop an alternative MM equation for HbA1c progression, which was then contrasted with the UKPDS 68 progression equation in illustrative scenarios.

RESULTS

A total of 68 studies were eligible for data extraction (mean follow-up time 4.1 years). HbA1c progression was highly heterogeneous across studies, varying with baseline HbA1c, treatment group and patient age. The MM equation was fitted with parameters for mean baseline HbA1c (8.3%), initial change in HbA1c (-0.62%) and upper quartile of maximum observed HbA1c (9.3%). Differences in HbA1c trajectories between the MM and UKPDS approaches altered the timing of therapy escalation in illustrative scenarios.

CONCLUSIONS

The MM represents an alternative approach to simulate HbA1c trajectories in T2DM models, as UKPDS data may not adequately reflect the heterogeneity of HbA1c profiles observed in clinical studies. However, the choice of approach should ultimately be determined by the characteristics of individual patients under consideration and the clinical face validity of the modelled trajectories.

Association of GA/HbA1c ratio and cognitive impairment in subjects with type 2 diabetes mellitus

AIMS

The aim of this study was to search for factors influencing cognitive impairment and to clarify the association between the fluctuation of blood glucose levels and cognitive impairment in elderly Japanese subjects with type 2 diabetes.

METHODS

We recruited 88 relatively elderly subjects (≥65years old) with type 2 diabetes who were hospitalized in Kawasaki Medical School from January 2014 to December 2015. We evaluated the fluctuation of blood glucose levels with glycoalbumin (GA)/hemoglobin A1c (HbA1c) ratio, and estimated cognitive impairment with Hasegawa dementia scale-revised (HDS-R) score and mini mental state examination (MMSE) score.

RESULTS

Multivariate analyses showed that GA/HbA1c ratio and urinary albumin excretion, but not hypoglycemia, were independent determinant factors for cognitive impairment in elderly Japanese subjects with type 2 diabetes.

CONCLUSIONS

The fluctuation of blood glucose levels per se is closely associated with cognitive impairment in elderly subjects with type 2 diabetes even when hypoglycemia is not accompanied. Since it is very easy to calculate GA/HbA1c ratio, we should check this ratio so that we can reduce the fluctuation of blood glucose levels especially in elderly subjects with type 2 diabetes.

Common neurodegenerative pathways in obesity, diabetes, and Alzheimer's disease

Cognitive decline in chronic diabetic patients is a less investigated topic. Diabetes and obesity are among the modifiable risk factors for Alzheimer's disease (AD), the most common form of dementia. Studies have identified several overlapping neurodegenerative mechanisms, including oxidative stress, mitochondrial dysfunction, and inflammation that are observed in these disorders. Advanced glycation end products generated by chronic hyperglycemia and their receptor RAGE provide critical links between diabetes and AD. Peripheral inflammation observed in obesity leads to insulin resistance and type 2 diabetes. Although the brain is an immune-privileged organ, cross-talks between peripheral and central inflammation have been reported. Damage to the blood brain barrier (BBB) as seen with aging can lead to infiltration of immune cells into the brain, leading to the exacerbation of central inflammation. Neuroinflammation, which has emerged as an important cause of cognitive dysfunction, could provide a central mechanism for aging-associated ailments. To further add to these injuries, adult neurogenesis that provides neuronal plasticity is also impaired in the diabetic brain. This review discusses these molecular mechanisms that link obesity, diabetes and AD. This article is part of a Special Issue entitled: Oxidative Stress and Mitochondrial Quality in Diabetes/Obesity and Critical Illness Spectrum of Diseases - edited by P. Hemachandra Reddy.

Effects of common chronic medical conditions on psychometric tests used to diagnose minimal hepatic encephalopathy

Many chronic medical conditions are accompanied by cognitive disturbances but these have only to a very limited extent been psychometrically quantified. An exception is liver cirrhosis where hepatic encephalopathy is an inherent risk and mild forms are diagnosed by psychometric tests. The preferred diagnostic test battery in cirrhosis is often the Continuous Reaction Time (CRT) and the Portosystemic Encephalopathy (PSE) tests but the effect on these of other medical conditions is not known. We aimed to examine the effects of common chronic (non-cirrhosis) medical conditions on the CRT and PSE tests. We studied 15 patients with heart failure (HF), 15 with end stage renal failure (ESRF), 15 with dysregulated type II diabetes (DMII), 15 with chronic obstructive pulmonary disease (COPD), and 15 healthy persons. We applied the CRT test, which is a 10-min computerized test measuring sustained attention and reaction time stability and the PSE test, which is a paper-pencil test battery consisting of 5 subtests. We found that a high fraction of the patients with HF (8/15, 0.002) or COPD (7/15, p = 0.006) had pathological CRT test results; and COPD patients also frequently had an abnormal PSE test result (6/15, p < 0.0001). Both tests were unaffected by ESRF and DMII. Half of the patients with HF or COPD had psychometrically measurable cognitive deficits, whereas those with ESRF or DMII had not. This adds to the understanding of the clinical consequences of chronic heart- and lung disease, and implies that the psychometric tests should be interpreted with great caution in cirrhosis patients with heart- or lung comorbidity.

Association of cognitive function with glucose tolerance and trajectories of glucose tolerance over 12 years in the AusDiab study

Introduction

We investigated the association between glucose tolerance status and trajectories of change in blood glucose, and cognitive function in adults aged 25 to 85.

Methods

The sample (n = 4547) was drawn from a national, population-based cohort study in Australia (AusDiab). Fasting plasma glucose (FPG), glycated haemoglobin (HbA1c) and general health were assessed at 0, 5 and 12 years. Covariates included age, education, body mass index, blood pressure and physical activity. At 12 years, participants completed assessments of memory, processing speed and verbal ability.

Results

Known diabetes at baseline was associated with slower processing speed at 12 years in both younger (25–59 years) and older (>60 years) age-groups. After 12 years of follow-up, adults aged < 60 with diabetes at baseline had a mean speed score of 49.17 (SE = 1.09) compared with 52.39 (SE = 0.20) in normals. Among younger males without diagnosed diabetes, reduced memory at 12 years was associated with higher HbA1c at 5 years (β = −0.91, SE = 0.26, p < 0.001). No effects were apparent for females or older males. Adjusting for insulin sensitivity (HOMA-%S) and hs-C reactive protein attenuated these associations, but depression and CVD risk did not. Latent class analysis was used to analyse the associations between trajectories of HbA1C and glucose over 12 years, and cognition. Identified classes were described as 1) normal and stable blood glucose over time (reference), 2) high intercept but stable blood glucose over time, and 3) increasing blood glucose over time. In both young males and females, high stable glucose measures were associated with poorer cognitive function after 12 years.

Conclusion

Those with type 2 diabetes, younger males with high non-diabetic HbA1c, and adults with high stable blood glucose are at increased risk of poorer cognition. The findings reinforce the need for management of diabetes risk factors in midlife.

Electronic supplementary material

The online version of this article (doi:10.1186/s13195-015-0131-4) contains supplementary material, which is available to authorized users.

The impact of diabetes on cognitive decline: potential vascular, metabolic, and psychosocial risk factors

Older people with type 2 diabetes are at increased risk of developing cognitive impairment, for which several potential risk factors have been proposed. The present article reviews evidence in people with type 2 diabetes for associations of cognitive impairment with a range of vascular, metabolic, and psychosocial risk factors, many of which have a higher prevalence in people with type 2 diabetes than in non-diabetic adults of a similar age. Definitive research studies in this field are few in number. The risk factors may be involved in causal pathways or may act as useful markers of cerebrovascular damage (or both), and for which relatively consistent evidence is available, include poor glycemic control, hypoglycemia, microvascular disease, inflammation, and depression. For macrovascular disease, the strength of the association with cognitive impairment appears to depend on which vascular system has been examined. A role for pre-morbid ability in young adulthood as influencing the risk of both diabetes and cognitive impairment has also been suggested. The importance of considering inter-relationships between risk factors when investigating their potential contribution to cognitive impairment in future investigations is discussed.

Haptoglobin genotype modulates the relationships of glycaemic control with cognitive function in elderly individuals with type 2 diabetes

AIMS/HYPOTHESIS

The purpose of this study was to investigate whether the association of glycaemic control with cognitive function is modulated by the haptoglobin 1-1 (Hp 1-1) genotype in cognitively normal elderly individuals with type 2 diabetes.

METHODS

In this cross-sectional study, we examined 793 participants who were genotyped for Hp (80 Hp 1-1 carriers and 713 Hp 1-1 non-carriers) enrolled in the Israel Diabetes and Cognitive Decline (IDCD) study. Glycaemic control was operationally defined by HbA1c level. The outcome measures were performance in four cognitive domains (episodic memory, attention/working memory, language/semantic categorisation, executive function) and overall cognition, a composite of the domains. Effect sizes were obtained from hierarchical linear regression analyses for each outcome measure, controlling for demographics, type 2 diabetes-related characteristics, cardiovascular risk factors, and their interactions with Hp genotype.

RESULTS

Interaction analyses showed significantly stronger associations of HbA1c with poorer cognitive function among Hp 1-1 carriers than non-carriers; attention/working memory (p < 0.001) and overall cognition (p = 0.003). For these two cognitive domains, associations were significant for Hp 1-1 carriers despite the small sample size (p < 0.00001 and p = 0.001, respectively), but not for non-carriers.

CONCLUSIONS/INTERPRETATION

Our findings suggest that patients with type 2 diabetes and poor glycaemic control carrying the Hp 1-1 genotype may be at increased risk of cognitive impairment, particularly in the attention/working memory domain. The association of glycaemic control with this domain may indicate cerebrovascular mechanisms.

Glucose regulation, cognition, and brain MRI in type 2 diabetes: a systematic review

Type 2 diabetes is associated with cognitive dysfunction and structural brain changes. Abnormalities in glucose regulation are involved in several complications related to type 2 diabetes, but their role in these cerebral complications is unclear. We systematically reviewed studies of the association between glucose regulation (glycaemia, hypoglycaemic events, insulin concentration, insulin resistance, and glucose-lowering treatment) and cognitive function and brain abnormalities on MRI in people with type 2 diabetes. The 86 papers included showed that glycaemia, particularly high HbA1c concentration and glucose variability, are negatively associated with cognitive function in people with type 2 diabetes without dementia. However, the strength of this association is weak, and HbA1c generally accounted for less than 10% of the variance in cognition. Importantly, few studies have measured long-term cerebral outcomes, such as dementia and structural brain changes on MRI, and the effect of glucose-lowering treatment on these outcomes. More randomised controlled trials are needed to establish the effect of glucose-lowering treatment on long-term cognitive function in people with type 2 diabetes.