An investigation of the population impact of variation in HbA1c levels in older people in England and Wales: from a population based multi-centre longitudinal study

Testing for associations between HbA1c levels, polygenic risk and brain health in UK Biobank (N = 39 283)

AIM

To investigate whether continuous HbA1c levels and HbA1c-polygenic risk scores (HbA1c-PRS) are significantly associated with worse brain health independent of type 2 diabetes (T2D) diagnosis (vs. not), by examining brain structure and cognitive test score phenotypes.

METHODS

Using UK Biobank data (n = 39 283), we tested whether HbA1c levels and/or HbA1c-PRS were associated with cognitive test scores and brain imaging phenotypes. We adjusted for confounders of age, sex, Townsend deprivation score, level of education, genotyping chip, eight genetic principal components, smoking, alcohol intake frequency, cholesterol medication, body mass index, T2D and apolipoprotein (APOE) e4 dosage.

RESULTS

We found an association between higher HbA1c levels and poorer performance on symbol digit substitution scores (standardized beta [β] = -0.022, P = .001) in the fully adjusted model. We also found an association between higher HbA1c levels and worse brain MRI phenotypes of grey matter (GM; fully-adjusted β = -0.026, P < .001), whole brain volume (β = -0.072, P = .0113) and a general factor of frontal lobe GM (β = -0.022, P < .001) in partially and fully adjusted models. HbA1c-PRS were significantly associated with GM volume in the fully adjusted model (β = -0.010, P = .0113); however, when adjusted for HbA1c levels, the association was not significant.

CONCLUSIONS

Our findings suggest that measured HbA1c is associated with poorer cognitive health, and that HbA1c-PRS do not add significant information to this.

Diabetes and cognitive decline

Epidemiologic studies have documented an association between diabetes and increased risk of cognitive decline in the elderly. Based on animal model studies, several mechanisms have been proposed to explain such an association, including central insulin signaling, neurodegeneration, brain amyloidosis, and neuroinflammation. Nevertheless, the exact mechanisms in humans remain poorly defined. It is reasonable, however, that many pathways may be involved in these patients leading to cognitive impairment. A major aim of clinicians is identifying early onset of neurologic signs and symptoms in elderly diabetics to improve quality of life of those with cognitive impairment and reduce costs associated with long-term complications. Several biomarkers have been proposed to identify diabetics at higher risk of developing dementia and diagnose early stage dementia. Although biomarkers of brain amyloidosis, neurodegeneration and synaptic plasticity are commonly used to diagnose dementia, especially Alzheimer disease, their role in diabetes remains unclear. The aim of this review is to explore the molecular mechanisms linking diabetes with cognitive decline and present the most important findings on the clinical use of biomarkers for diagnosing and predicting early cognitive decline in diabetics.

Type 2 Diabetes, Glycemic Control, and Their Association With Dementia and Its Major Subtypes: Findings From the Swedish National Diabetes Register

OBJECTIVE

Type 2 diabetes has been associated with high dementia risk. However, the links to different dementia subtypes is unclear. We examined to what extent type 2 diabetes is associated with dementia subtypes and whether such associations differed by glycemic control.

RESEARCH DESIGN AND METHODS

We used data from the Swedish National Diabetes Register and included 378,299 patients with type 2 diabetes and 1,886,022 control subjects matched for age, sex, and county randomly selected from the Swedish Total Population Register. The outcomes were incidence of Alzheimer disease, vascular dementia, and nonvascular dementia. The association of type 2 diabetes with dementia was stratified by baseline glycated hemoglobin (HbA1c) in patients with type 2 diabetes only. Cox regression was used to study the excess risk of outcomes.

RESULTS

Over the follow-up (median 6.8 years), dementia developed in 11,508 (3.0%) patients with type 2 diabetes and 52,244 (2.7%) control subjects. The strongest association was observed for vascular dementia, with patients with type 2 diabetes compared with control subjects having a hazard ratio [HR] of 1.34 (95% CI 1.28, 1.41). The association of type 2 diabetes with nonvascular dementia was more modest (HR 1.10 [95% CI 1.07, 1.13]). However, risk for Alzheimer disease was lower in patients with type 2 diabetes than in control subjects (HR 0.94 [95% CI 0.90, 0.99]). When the analyses were stratified by circulating concentrations of HbA1c, a dose-response association was observed.

CONCLUSIONS

The association of type 2 diabetes with dementia differs by subtypes of dementia. The strongest detrimental association is observed for vascular dementia. Moreover, patients with type 2 diabetes with poor glycemic control have an increased risk of developing vascular and nonvascular dementia.

Advanced Glycation End Product Formation in Human Cerebral Cortex Increases With Alzheimer-Type Neuropathologic Changes but Is Not Independently Associated With Dementia in a Population-Derived Aging Brain Cohort

Diabetes mellitus is a risk factor for dementia, and nonenzymatic glycosylation of macromolecules results in formation of advanced glycation end-products (AGEs). We determined the variation in AGE formation in brains from the Cognitive Function and Ageing Study population-representative neuropathology cohort. AGEs were measured on temporal neocortex by enzyme-linked immunosorbent assay (ELISA) and cell-type specific expression on neurons, astrocytes and endothelium was detected by immunohistochemistry and assessed semiquantitatively. Fifteen percent of the cohort had self-reported diabetes, which was not significantly associated with dementia status at death or neuropathology measures. AGEs were expressed on neurons, astrocytes and endothelium and overall expression showed a positively skewed distribution in the population. AGE measures were not significantly associated with dementia. AGE measured by ELISA increased with Consortium to Establish a Registry for Alzheimer's Disease (CERAD) neurofibrillary tangle score (p = 0.03) and Thal Aβ phase (p = 0.04), while AGE expression on neurons (and astrocytes), detected immunohistochemically, increased with increasing Braak tangle stage (p < 0.001), CERAD tangle score (p = 0.002), and neuritic plaques (p = 0.01). Measures of AGE did not show significant associations with cerebral amyloid angiopathy, microinfarcts or neuroinflammation. In conclusion, AGE expression increases with Alzheimer's neuropathology, particular later stages but is not independently associated with dementia. AGE formation is likely to be important for impaired brain cell function in aging and Alzheimer's.

＜Editors' Choice＞ Association between green tea intake and risk of cognitive decline, considering glycated hemoglobin level, in older Japanese adults: the NILS-LSA study

Positive and negative associations with risk of cognitive decline have been reported for glycated hemoglobin (HbA1c) level and green tea (GT) intake, respectively. This study aimed to assess whether the reduction in the risk of cognitive decline with GT intake depended on HbA1c level. The participants were aged ≥60 years at baseline in the cohort study, wherein examinations were conducted biennially from 2000 to 2012. Subjects (n=1,304) who had no cognitive decline during the first survey and who had participated in the follow-up survey at least once were included. The follow-up end point was the first screening time point for cognitive decline (Mini-Mental State Examination score <27) or the last survey participation. With reference to the Japanese Diabetes Society guideline, the cut-off points for HbA1c level were set at 5.6%, 6.0%, and 6.5%, and lower and higher groups were assigned for each cut-off point. In a multiple Cox proportional hazard model, an interaction between GT intake and HbA1c groups for cognitive decline was observed only at HbA1c 6.0% (P-value for interaction [with Bonferroni's correction] <0.05/3). Lower risks of cognitive decline were found for the HbA1c ≥5.6%, ≥6.0%, and <6.5% groups (hazard ratios: 0.59, 0.34, and 0.77; 95% confidence intervals: 0.41-0.88, 0.19-0.61, and 0.56-1.08 for "≥4 times a day" vs. "<once a day" GT intake, respectively; P-value for trend: 0.06, <0.01, and 0.09, respectively). With respect to blood glucose level, our cohort study showed non-uniformly reduced risk of cognitive decline with GT intake among older Japanese adults.

Risk of dementia and cognitive dysfunction in individuals with diabetes or elevated blood glucose

AIMS

To determine the risk of dementia in patients with type 1 or type 2 diabetes and in individuals with glycosylated haemoglobin, type A1C (HbA1c) of ⩾48 mmol/mol, which is the diagnostic limit for diabetes.

METHODS

We included the following cohorts: all incident diabetes cases aged 15 or above registered in the National Diabetes Registry (NDR) from January 2000 through December 2012 (n = 148 036) and a reference population, adult participants from the Glostrup cohort (n = 16 801), the ADDITION Study (n = 26 586) and Copenhagen Aging and Midlife Biobank (CAMB) (n = 5408). Using these cohorts, we analysed if a diagnosis of type 1 or type 2 diabetes in the NDR or HbA1c level of ⩾ 6.5% (48 mmol/mol) in the cohorts increased risk of dementia in the Danish National Patient Registry or cognitive performance assessed by the Intelligenz-Struktur-Test 2000R (IST2000R).

RESULTS

A diagnosis of type 1 or type 2 diabetes in the NDR was associated with increased risk of dementia diagnosed both before or after age 65 as well as across different subtypes of dementia. Self-reported diabetes or high HbA1c levels were associated with lower cognitive performance (p = 0.004), while high HbA1c was associated with increased risk of dementia (HR 1.94 (1.10-3.44) in the Glostrup cohort but not in the ADDITION Study (HR 0.96 (0.57-1.61)).

CONCLUSIONS

Both type 1 and type 2 diabetes are associated with an increased risk of dementia, while the importance of screening-detected elevated HbA1c remains less clear.

Importance of Treatment Status in Links Between Type 2 Diabetes and Alzheimer's Disease

OBJECTIVE

To investigate relationships among type 2 diabetes treatment, Alzheimer's disease(AD) biomarkers, and risk for dementia.

RESEARCH DESIGN AND METHODS

Participants were from the Alzheimer's Disease Neuroimaging Initiative (N = 1,289) and were dementia-free at baseline and underwent health assessment, cognitive testing, and MRI. A subset (n = 900) obtained a lumbar puncture to determine cerebrospinal fluid (CSF) phosphorylated tau (p-tau), total tau (t-tau), and β-amyloid 1-42 (Aβ1-42). Participants were grouped by fasting blood glucose and medication history: euglycemia (EU), prediabetes (PD), untreated diabetes (UD), and treated diabetes (TD). Relationships were investigated between treatment status and CSF biomarkers and risk for dementia.

RESULTS

The UD group displayed greater p-tau, t-tau, and p-tau/Aβ1-42 levels than the EU, PD, and TD groups (P values <0.05) and higher t-tau/Aβ1-42 than the EU and PD groups (P values <0.05). The UD group progressed to dementia at higher rates than the EU group (hazard ratio 1.602 [95% CI 1.057-2.429]; P = 0.026).

CONCLUSIONS

Treatment status may alter the relationship between type 2 diabetes and both AD biomarker profile and risk for dementia. UD is associated with elevated tau pathology and risk for dementia, whereas TD is not. Although this study is observational and therefore causality cannot be inferred, findings support the potential importance of treatment status in AD risk associated with type 2 diabetes.

Hemoglobin A1c and 10-year information processing speed in Japanese community dwellers

Background

Hyperglycemia is believed to be a risk factor for cognitive decline, but the longitudinal relationship between hyperglycemia and cognitive decline in the Japanese population is unclear. The present study aimed to clarify the association between blood glucose levels and information processing ability in middle-aged and older adults.

Methods

The subjects were 866 men and 815 women aged 40–79 years not taking medication for diabetes who participated in the first study wave (1997–2000) and then participated at least once in the subsequent six study waves (2000–2012) of the National Institute for Longevity Sciences—Longitudinal Study of Aging, Japan. Hemoglobin A1c (HbA1c) levels were categorized into four groups (< 5.6, 5.6 to < 6.0, 6.0 to < 6.5, ≥ 6.5%), and a mixed-effects model was used to evaluate the effects of the HbA1c level (four groups) on repeated measures of information processing speed. The models also included baseline age, body mass index, ethanol intake, smoking status, educational level, family income, and history of stroke, hypertension, heart disease, and dyslipidemia as covariates.

Results

Mean (standard deviation) HbA1c and follow-up time in participants were 5.2 (0.5) % and 10.0 (3.6) years, respectively. A linear mixed model showed that the main effect of the four HbA1c groups on information processing ability was not significant in either men or women, but the interaction of HbA1c and time with information processing speed in the higher HbA1c level groups (≥ 6.5% group in men, 6.0 to < 6.5% and ≥ 6.5% groups in women) was significant compared to the lower HbA1c level (< 5.6%) group (P < 0.05). When the slope of information processing speed by HbA1c level at baseline was examined, the slope of information processing speed in the higher HbA1c level (≥ 6.5%) group was higher than in the lower HbA1c level (< 5.6%) group, both in men (− 0.31/year) and in women (− 0.30/year), as well as in women with an HbA1c level of 6.0 to < 6.5% (− 0.40/year).

Conclusions

Higher baseline HbA1c was associated with greater subsequent decline in information processing ability in Japanese community dwellers, even with the pre-clinical HbA1c level (6.0 to < 6.5%) in women. The results suggest that good glycemic control or prevention of hyperglycemia may contribute to maintaining information processing ability.

Electronic supplementary material

The online version of this article (10.1186/s12199-019-0778-8) contains supplementary material, which is available to authorized users.

The Effects of Substance Abuse on Blood Glucose Parameters in Patients with Diabetes: A Systematic Review and Meta-Analysis

Background: People who abuse substances are at increased risk of metabolic syndrome and diabetes resulting partly from increased cell damage and due to the effects of opioids on glucose homeostasis. Therefore, people with diabetes who abuse substances may carry greater health risks than the general population resulting from their effect on glucose metabolism. These substances may be in the form of cannabis, hallucinogens, opioids, and stimulants. Therefore, the aim of this review was to evaluate the effects of substance abuse on blood glucose parameters in patients with diabetes. Method: Databases including Embase, Psycho-Info, Google Scholar and PubMed were searched systematically for relevant articles from database inception to May 2018. Search terms including medical subject headings (MeSH) based on the Population, Intervention, Comparator and Outcomes (PICO) framework was used to access the databases. Eligible articles were selected based on set inclusion and exclusion criteria. The articles reviewed were evaluated for quality and meta-analysis and sensitivity analysis were carried out using the Review Manager (RevMan 5.3, The Cochrane Collaboration, Copenhagen, Denmark). The Random effects model was used for the data analysis. Results: Twelve studies which met the inclusion criteria were included in the systematic review, while nine articles were selected for the meta-analysis. The results of the meta-analysis showed that substance abuse does not have significant effects (p > 0.05) on postprandial blood glucose and glycated haemoglobin in patients with diabetes. With respect to the effect of substance abuse on fasting blood glucose, while this was significant (p < 0.05) following meta-analysis, the results of the sensitivity test did not demonstrate any significant difference (p > 0.05) between patients who abused substances compared with control. This would suggest that the effect of substance abuse on fasting blood glucose in these patients was not very reliable or not consistent. Conclusions: The effect of substance abuse on glycated haemoglobin and postprandial blood glucose in patients with diabetes was not significant. In the meta-analysis, while the value was slightly lower with respect to postprandial blood glucose, this was slightly higher in relation to HbA1c in the substance abuse group compared with control. On the other hand, the effect of substance abuse on fasting blood glucose was significant (p = 0.03) compared with control, but this was attenuated following a sensitivity test. A range of factors including eating habits, characteristics of drugs, erratic lifestyle of patients may explain the outcome of this review. There is the need for randomised controlled trials that will include diet and medication history in order to fully understand the effect of substance abuse on blood glucose parameters in patients with diabetes.

Early Cognitive Deficits in Type 2 Diabetes: A Population-Based Study

Evidence links type 2 diabetes to dementia risk. However, our knowledge on the initial cognitive deficits in diabetic individuals and the factors that might promote such deficits is still limited. This study aimed to identify the cognitive domains initially impaired by diabetes and the factors that play a role in this first stage. Within the population-based Swedish National Study on Aging and Care–Kungsholmen, 2305 cognitively intact participants aged ≥60 y were identified. Attention/working memory, perceptual speed, category fluency, letter fluency, semantic memory, and episodic memory were assessed. Diabetes (controlled and uncontrolled) and prediabetes were ascertained by clinicians, who also collected information on vascular disorders (hypertension, heart diseases, and stroke) and vascular risk factors (VRFs, including smoking and overweight/obesity). Data were analyzed with linear regression models. Overall, 196 participants (8.5%) had diabetes, of which 144 (73.5%) had elevated glycaemia (uncontrolled diabetes); 571 (24.8%) persons had prediabetes. In addition, diabetes, mainly uncontrolled, was related to lower performance in perceptual speed (β – 1.10 [95% CI – 1.98, – 0.23]), category fluency (β – 1.27 [95% CI – 2.52, – 0.03]), and digit span forward (β – 0.35 [95% CI – 0.54, – 0.17]). Critically, these associations were present only among APOEɛ4 non–carriers. The associations of diabetes with perceptual speed and category fluency were present only among participants with VRFs or vascular disorders. Diabetes, especially uncontrolled diabetes, is associated with poorer performance in perceptual speed, category fluency, and attention/primary memory. VRFs, vascular disorders, and APOE status play a role in these associations.

As queixas subjetivas de memória num cuidado de saúde primário: Um estudo follow up

Objetivo

As queixas subjetivas de memória (QSM) são um fator clínico relevante e uma das principais queixas feitas aos médicos de família por adultos e adultos idosos. Este estudo, realizado numa Unidade de Saúde Familiar da Região Centro de Portugal, teve como objetivo caracterizar as QSM em função de variáveis sociodemográficas, clínicas, cognitivas, emocionais e de qualidade de vida.

Método

Este estudo, de coorte prospetivo em dois momentos, procurou explorar a evolução das QSM durante 18 meses e quais os fatores que se associam. Foi levado a cabo numa amostra de 19 adultos e de adultos idosos com idades compreendidas entre os 55 e os 81 anos (79.2% do sexo feminino). Os dados foram recolhidos por entrevistas semiestruturadas e sempre que possível foram consultados os processos clínicos. Foram utilizados como instrumentos de medida o Mini Mental State Examination (MMSE), o Montreal Cognitive Assessment (MoCA), a Escala de Queixas de Memória (EQM), a Escala de Depressão Geriátrica (GDS), o Inventário de Ansiedade Geriátrica (GAI), a Avaliação de Qualidade de Vida da Organização Mundial de Saúde (WHOQOL-Bref) e por um questionário sociodemográfico e clínico construído para o efeito.

Resultados

No segundo momento avaliativo, todos os participantes evidenciam QSM, sendo estas influenciadas significativamente pela idade. Houve ainda um aumento da sintomatologia depressiva e ansiógena, dos valores da Hemoglobina glicosilada (HbA1c) e do número de medicamentos consumidos, com particular ênfase nos anti hipertensores.

Conclusão

As QSM deverão ser objeto de preocupação e vigilância do médico de família, uma vez que podem representar um sintoma relevante para a identificação precoce de um processo demencial.

No more broken hearts: weight loss after bariatric surgery returns patients' postoperative risk to baseline following coronary surgery

BACKGROUND

The obesity epidemic is associated with a rise in coronary surgeries because obesity is a risk factor for coronary artery disease. Bariatric surgery is linked to improvement in cardiovascular co-morbidities and left ventricular function. No studies have investigated survival advantage in postoperative bariatric patients after coronary surgery.

OBJECTIVES

To determine if there is a benefit after coronary surgery in patients who have previously undergone bariatric surgery.

SETTING

National Inpatient Sample.

METHODS

We performed a retrospective, cross-sectional analysis of the National Inpatient Sample database from 2003 to 2010. We selected bariatric surgical patients who later underwent coronary surgery (n = 257). A comparison of postoperative complications and mortality after coronary surgery were compared with controls (n = 1442) using χ² tests, linear regression analysis, and multivariate logistical regression models.

RESULTS

A subset population was identified as having undergone coronary surgery (n = 1699); of this population, 257 patients had previously undergone bariatric surgery. They were compared with 1442 controls. The majority was male (67.2%), white (82.6%), and treated in an urban environment (96.8%). Patients with bariatric surgery assumed the risk of postoperative complications after coronary surgery that was associated with their new body mass index (BMI) (BMI<25 kg/m²: odds ratio (OR) 1.01, 95% CI .76-1.34, P = .94; BMI 25 to<35 kg/m²: OR .20, 95% CI .02-².16, P = .19; BMI≥35 kg/m²: OR>999.9, 95% CI .18 to>999.9, P = .07). Length of stay was significantly longer in postbariatric patients (BMI<25, OR 1.62, 95% CI 1.14-2.30, P = .007).

CONCLUSIONS

Postoperative bariatric patients have a return to baseline risk of morbidity and mortality after coronary surgery.

The Effect of Undiagnosed Diabetes on the Association Between Self-Reported Diabetes and Cognitive Impairment Among Older Mexican Adults

PURPOSE

To study the effect of undiagnosed diabetes on the relationship between self-reported diabetes and cognitive impairment.

METHODS

Data were from 1033 participants aged ≥60 from Wave III (2012) of the Mexican Health and Aging Study. Participants were classified as nondiabetic (n = 589), undiagnosed diabetic (n = 201), and self-reported diabetic (n = 243). Multivariate logistic regression models were used to estimate the relationship between self-reported diabetes and severity of cognitive impairment (nonimpaired, moderate impaired, severe impaired).

RESULTS

Self-reported diabetes was associated with significantly higher odds for severe, but not moderate, cognitive impairment (odds ratio [OR] = 2.70, 95% confidence interval [CI] = 1.39-5.32). The association between self-reported diabetes and severe cognitive impairment decreased by 6.3% when undiagnosed diabetics were included in the nondiabetic category and by 30.4% when undiagnosed diabetics were included in the self-reported diabetes category.

DISCUSSION

The association between self-reported diabetes and severe cognitive impairment is underestimated when undiagnosed diabetics are not differentiated from self-reported diabetics and nondiabetics.

Clinical features of incidental mild cognitive impairment and dementia in a population-based study

AIM

The number of people with dementia is rapidly increasing as populations around the world age. It is important to grasp the characteristic features of mild cognitive impairment (MCI) for early detection and prevention of dementia.

METHODS

We examined 408 individuals recruited from a health checkup for metabolic syndrome, which comprised three groups: normal (n = 325), MCI (n = 55) and apparent cognitive decline (ACD; n = 28). We compared cognitive/affective functions and exercise/hobby habits with assessments of vascular risk factors and results from computerized touch-panel tests.

RESULTS

Among the 408 individuals, 93.1% showed normal scores on the Mini-Mental State Examination, and 6.9% had ACD. Among the normal Mini-Mental State Examination participants, 14.5% had MCI (13.5% of all participants). The three groups of participants showed significant differences in age, education, systolic blood pressure, glycosylated hemoglobin and high-density lipoprotein cholesterol level. Even within the normal range, those in the MCI group showed significantly lower cognitive function than those in the normal group. Scores on the Geriatric Depression Scale were greater in the MCI group, and "day-night reversal" was worse in the ACD group. Scores on touch-panel screening tests were significantly worse in the MCI and ACD groups than in the normal group. Participants showed better cognitive and affective function if they exercised regularly or had hobbies.

CONCLUSIONS

Incidental MCI and ACD had prevalences of 13.5% and 6.9%, respectively, in the population-based study. Participants with these conditions showed cognitive/affective decline and impairment on computerized touch-panel tests in relation to vascular risk factors and exercise/hobbies. Geriatr Gerontol Int 2017; 17: 722-729.

HbA1c and Risks of All-Cause and Cause-Specific Death in Subjects without Known Diabetes: A Dose-Response Meta-Analysis of Prospective Cohort Studies

Whether HbA_1c levels are associated with mortality in subjects without known diabetes remains controversial. Moreover, the shape of the dose–response relationship on this topic is unclear. Therefore, a dose–response meta-analysis was conducted. PubMed and EMBASE were searched. Summary hazard ratios (HRs) were calculated using a random-effects model. Twelve studies were included. The summary HR per 1% increase in HbA_1c level was 1.03 [95% confidence interval (CI) = 1.01–1.04] for all-cause mortality, 1.05 [95% CI = 1.02–1.07) for cardiovascular disease (CVD) mortality, and 1.02 (95% CI = 0.99–1.07) for cancer mortality. After excluding subjects with undiagnosed diabetes, the aforementioned associations remained significant for CVD mortality only. After further excluding subjects with prediabetes, all aforementioned associations presented non-significance. Evidence of a non-linear association between HbA_1c and mortality from all causes, CVD and cancer was found (all P_{non-linearity} < 0.05). The dose–response curves were relatively flat for HbA_1c less than around 5.7%, and rose steeply thereafter. In conclusion, higher HbA_1c level is associated with increased mortality from all causes and CVD among subjects without known diabetes. However, this association is driven by those with undiagnosed diabetes or prediabetes. The results regarding cancer mortality should be treated with caution due to limited studies.

Evaluating the Association between Diabetes, Cognitive Decline and Dementia

The aim of this article is to review the association between diabetes mellitus, cognitive decline and dementia, including the effects of cognitive decline and dementia on self management of diabetes. This is a literature review of primary research articles. A number of contemporary research articles that met the inclusion criteria were selected for this review paper. These articles were selected using a number of search strategies and electronic databases, such as EBSCOhost Research and SwetsWise databases. The duration of diabetes, glycated haemoglobin levels and glycaemic fluctuations were associated with cognitive decline and dementia. Similarly, hypoglycaemia was significantly related to increased risk of developing cognitive decline and dementia. Furthermore, cognitive decline and dementia were associated with poorer diabetes management. There is evidence of the association between diabetes, cognitive decline and dementia including the shared pathogenesis between diabetes and Alzheimer’s disease. In addition, the self management of diabetes is affected by dementia and cognitive decline. It could be suggested that the association between diabetes and dementia is bidirectional with the potential to proceed to a vicious cycle. Further studies are needed in order to fully establish the relationship between diabetes, cognitive decline and dementia. Patients who have diabetes and dementia could benefit from structured education strategies, which should involve empowerment programmes and lifestyle changes. The detection of cognitive decline should highlight the need for education strategies.

Association between hemoglobin A1c and all-cause mortality: results of the mortality follow-up of the German National Health Interview and Examination Survey 1998

OBJECTIVE

This study examined the association of HbA1c-defined glycemic status and continuous HbA1c with all-cause mortality.

RESEARCH DESIGN AND METHODS

The study population comprised 6,299 participants (aged 18-79 years) of the German National Health Interview and Examination Survey 1998, who were followed up for mortality for an average of 11.6 years. Glycemic status was defined as known diabetes (self-reported diagnosis or intake of antidiabetic medication) and based on HbA1c levels according to American Diabetes Association diagnostic criteria as undiagnosed diabetes (≥6.5% [≥48 mmol/mol]), prediabetes with very high (6.0-6.4% [42-46 mmol/mol]) or high diabetes risk (5.7-5.9% [39-41 mmol/mol]), and normoglycemia (<5.7% [<39 mmol/mol]). Associations between glycemic status and mortality were examined by Cox regression adjusting for age, sex, education, lifestyle factors, anthropometric measures, and history of chronic diseases (reference: normoglycemia). Spline models were fitted to investigate associations between continuous HbA1c and mortality among participants without known diabetes.

RESULTS

Excess mortality risk was observed for participants with known diabetes (hazard ratio 1.41 [95% CI 1.08-1.84]) and undiagnosed diabetes (1.63 [1.23-2.17]) but not for those with high (1.02 [0.80-1.30]) or very high diabetes risk (0.87 [0.67-1.13]). Spline models revealed a U-shaped association, with lowest risk at HbA1c levels 5.4-5.6% (36-38 mmol/mol) and a significantly increased risk at ≤5.0% (≤31 mmol/mol) and ≥6.4% (≥46 mmol/mol).

CONCLUSIONS

Unlike known and undiagnosed diabetes, HbA1c levels in the prediabetic range were not associated with an increased mortality risk. The observed U-shaped relationship adds to existing evidence that not only high but also low HbA1c levels might be associated with all-cause mortality.

Cognitive dysfunction in type 2 diabetes patients accompanied with obstructive sleep apnea syndrome

OBJECTIVE

To investigate cognitive dysfunction of type 2 diabetes patients accompanied with obstructive sleep apnea syndrome (OSAS), and to analyze its relevant characteristics.

METHODS

Total 115 type 2 diabetes patients were divided into OSAS group (O group, n=83) and non-OSAS group (N group, n=32); Physical examination patients (C1 group, n=64) and OSAS patients without diabetes (C2 group, n=47) served as the control group. Apnea-hypopnea index (AHI), nocturnal lowest saturation of pulse oxygen (LSPO2) and simple mental state examination scale (MMSE) were evaluated.

RESULTS

Among diabetes patients, patients with OSAS have lower glycated hemoglobin, platelet count, thrombocytocrit, MMSE score and lowest mean arterial oxygen than non-OSAS patients; cognitive dysfunction state and glycemic control of patients are related to their diabetic duration, and then along with increase of diabetic duration, glycemic control becomes poor, so that cognitive dysfunction becomes more and more obvious.

CONCLUSION

Along with increased diabetic duration in type 2 diabetes accompanied with OSAS, glycemic control becomes poor, so that cognitive dysfunction more easily occurs. Meanwhile, coagulation function of blood system in OSAS patients with diabetes is impacted to some extent.

Understanding the type 2 diabetes mellitus and cardiovascular disease risk paradox

Patients with diabetes have approximately a 2-fold increase in the risk for coronary heart disease, stroke, and death from vascular causes compared with patients who do not have diabetes. Interventions targeted at modifiable risk factors, such as smoking cessation and management of hypertension and dyslipidemia, reduce the risk of cardiovascular disease (CVD) in patients with type 2 diabetes mellitus (T2DM). Paradoxically, large randomized studies have failed to conclusively show that intensively lowering glucose reduces CVD event rates in patients with T2DM, despite pathophysiologic and epidemiologic evidence suggesting that hyperglycemia contributes to CVD. Although initiation of intensive glycemic control early in the disease course may be associated with a reduction in the long-term risk of cardiovascular (CV) events, this approach in those with long-standing or complicated T2DM is not of clear benefit and may even be harmful in some. Failure to mitigate risk with antihyperglycemic therapy and the potential for some treatments to increase CVD risk underlies a treatment paradox. New glucose-lowering therapies are now subject to close scrutiny for CV safety before and after drug approval. Results from the first trials designed to meet the recent CV regulatory requirements have shown no increased risk of major adverse CV events but also no CV benefit from dipeptidyl peptidase-4 inhibitor therapy, as well as a potentially increased risk of hospitalization for heart failure. Conclusive evidence of CV risk reduction with glucose-lowering therapy is still lacking and scrutiny of additional agents is necessary. Type 2 diabetes mellitus is a heterogeneous disease, for which patient-centered, individualized care, and goal-setting is appropriate. Interventions that focus on the management of CV risk factors and glucose lowering with medications that are not cardiotoxic represent an optimal and attainable treatment approach.

Psychosis prevalence and physical, metabolic and cognitive co-morbidity: data from the second Australian national survey of psychosis

BACKGROUND

There are insufficient data from nationwide surveys on the prevalence of specific psychotic disorders and associated co-morbidities.

METHOD

The 2010 Australian national psychosis survey used a two-phase design to draw a representative sample of adults aged 18-64 years with psychotic disorders in contact with public treatment services from an estimated resident population of 1 464 923 adults. This paper is based on data from 1642 participants with an International Classification of Diseases (ICD)-10 psychotic disorder. Its aim is to present estimates of treated prevalence and lifetime morbid risk of psychosis, and to describe the cognitive, physical health and substance use profiles of participants.

RESULTS

The 1-month treated prevalence of psychotic disorders was 3.10 cases per 1000 population aged 18-64 years, not accounting for people solely accessing primary care services; lifetime morbid risk was 3.45 per 1000. Mean premorbid intelligence quotient was approximately 0.5 s.d.s below the population mean; current cognitive ability (measured with a digit symbol coding task) was 1.6 s.d.s below the population mean. For both cognitive tests, higher scores were significantly associated with better independent functioning. The prevalence of the metabolic syndrome was high, affecting 60.8% of participants, and pervasive across diagnostic groups. Of the participants, two-thirds (65.9%) were current smokers, 47.4% were obese and 32.4% were sedentary. Of the participants, half (49.8%) had a lifetime history of alcohol abuse/dependence and 50.8% lifetime cannabis abuse/dependence.

CONCLUSIONS

Our findings highlight the need for comprehensive, integrative models of recovery to maximize the potential for good health and quality of life for people with psychotic illness.

Dysglycemia, brain volume and vascular lesions on MRI in a memory clinic population

OBJECTIVE

It is unclear, if the association between abnormalities in glucose metabolism (dysglycemia) and impaired cognitive functioning is primarily driven by degenerative or vascular brain damage. We therefore examined the relation between dysglycemia and brain volume and vascular lesions on MRI in a memory clinic population.

METHODS

The relations between markers of glycemia (HbA1c and fasting glucose levels) and normalized brain volume, medial temporal lobe atrophy and vascular lesions (white matter hyperintensities, lacunes) were assessed in 274 consecutive patients attending a memory clinic, using linear regression analyses.

RESULTS

Clinical diagnoses were subjective complaints (n=117), mild cognitive impairment (n=62), Alzheimer's disease (n=61) and other type of dementia (n=34). Twenty patients had a history of diabetes. Across the whole study population there was no relation between HbA1c or fasting glucose and the brain MRI measurements, after adjustments for age, sex and diagnostic group. Secondary analyses after stratification by diabetes status, diagnosis and median age (67 years) did not change the results.

CONCLUSION

In this memory clinic population, dysglycemia was not associated with either brain volume or vascular lesions. Apparently, dysglycemia is not associated with a specific class of brain pathology in patients with cognitive complaints.

Spatial memory impairments in a prediabetic rat model

Diabetes is associated with an increased risk for brain disorders, namely cognitive impairments associated with hippocampal dysfunction underlying diabetic encephalopathy. However, the impact of a prediabetic state on cognitive function is unknown. Therefore, we now investigated whether spatial learning and memory deficits and the underlying hippocampal dysfunction were already present in a prediabetic animal model. Adult Wistar rats drinking high-sucrose (HSu) diet (35% sucrose solution during 9 weeks) were compared to controls' drinking water. HSu rats exhibited fasting normoglycemia accompanied by hyperinsulinemia and hypertriglyceridemia in the fed state, and insulin resistance with impaired glucose tolerance confirming them as a prediabetic rodent model. HSu rats displayed a poorer performance in hippocampal-dependent short- and long-term spatial memory performance, assessed with the modified Y-maze and Morris water maze tasks, respectively; this was accompanied by a reduction of insulin receptor-β density with normal levels of insulin receptor substrate-1 pSer636/639, and decreased hippocampal glucocorticoid receptor levels without changes of the plasma corticosterone levels. Importantly, HSu animals exhibited increased hippocampal levels of AMPA and NMDA receptor subunits GluA1 and GLUN1, respectively, whereas the levels of protein markers related to nerve terminals (synaptophysin) and oxidative stress/inflammation (HNE, RAGE, TNF-α) remained unaltered. These findings indicate that 9 weeks of sucrose consumption resulted in a metabolic condition suggestive of a prediabetic state, which translated into short- and long-term spatial memory deficits accompanied by alterations in hippocampal glutamatergic neurotransmission and abnormal glucocorticoid signaling.

Multiple complications and frequent severe hypoglycaemia in 'elderly' and 'old' patients with Type 1 diabetes

AIM

Elderly and old patients with Type 1 diabetes represent a growing population that requires thorough diabetes care. The increasing relevance of this subgroup, however, plays only a minor role in the literature. Here, we describe elderly patients with Type 1 diabetes on the basis of a large multi-centre database in order to point out special features of this population.

METHOD

Data of 64609 patients with Type 1 diabetes treated by 350 qualified diabetes treatment centres were assessed and analysed by age group.

RESULTS

Compared with the age group ≤ 60 years, patients aged >60 years (n=3610 61-80 years and n=377 >80 years old) were characterized by a longer diabetes duration (27.7 vs. 7.7 years), an almost double risk for severe hypoglycaemia (40.1 vs. 24.3/100 patient-years), a lower level of HbA(1c) [60 vs. 67 mmol/mol (7.6 vs. 8.3%)] and higher percentages of microalbuminuria (34.5 vs. 15.6%), diabetic retinopathy (45.2 vs. 8.3%), myocardial infarction (9.0 vs. 0.4%) or stroke (6.8 vs. 0.3%). Elderly patients used insulin pumps less frequently (12.2 vs. 23.8%), but more often used conventional premixed insulin treatment (10.8 vs. 3.8%). Differences between elderly and younger patient groups were significant, respectively.

CONCLUSION

Diabetes care of elderly patients with Type 1 diabetes involves individualized treatment concepts. Increased hypoglycaemia risk and functional impairment attributable to diabetes-associated and/or age-related disorders must be taken into account.

The association of diabetes and dementia and possible implications for nondiabetic populations

Diabetes and prediabetic states have consistently been shown to be risk factors for cognitive decline, mild cognitive impairment and dementia. The importance of these findings is that diabetes and diabetes-related factors are modifiable, potentially permitting interventions aimed at postponing or preventing dementia. However, diabetes control cannot yet be implemented universally in diabetic subjects as a strategy for dementia prevention since the mechanisms by which diabetes impairs brain function and cognition are not fully understood. It is not clear which of the diabetes-related factors is crucial to this relationship. In addition, strict diabetic control has been demonstrated to carry risk for certain diabetic populations. The aim of the current article is to discuss current understanding of the relationships of diabetes and some of its characteristics with dementia, and suggest future questions to be answered.

Disability in older people with diabetes: issues for the clinician

Diabetes may become a disabling disease due to diverse mechanisms. Many patients have evidence of physical or cognitive impairments that can markedly influence their ability to diabetes self manage and adversely affect possible outcomes of diabetes care. A screening process for impairment is therefore needed and in frail patients a comprehensive gerontological assessment should be used to improve the efficiency of care. A diabetes educational programme adapted to this population, which has involved the main care-giver has shown its efficacy to improve risk factor control and quality of life in a safer way. The experience of case-managers according to a model of heart failure may be promising for the future.

Association between HbA1c and cardiovascular disease mortality in older Hong Kong Chinese with diabetes

OBJECTIVE

To examine the association between baseline HbA(1c) level and mortality attributable to all-cause, cardiovascular disease, coronary heart disease and stroke.

METHODS

A total of 2137 Chinese aged 65 years or above attending the Elderly Health Service, Department of Health, Hong Kong, with diagnosed diabetes had HbA(1c) measured during 1998 to 2000 and were followed up to 2009. Information on socio-economic position, lifestyle factors and disease history was collected. Hazard ratios and 95% confidence intervals with adjustment for potential confounders were calculated using Cox's proportional hazards models.

RESULTS

After an average of 7.9 years of follow-up, 540 participants had died. After adjusting for potential confounders, higher HbA(1c) (≥ 69 mmol/mol, 8.5%) increased the risk of cardiovascular disease (hazard ratio 2.11;95% CI 1.37-3.25) and stroke mortality (hazard ratio 2.43; 95% CI 1.06-5.55) compared with HbA(1c) of 58-68 mmol/mol (7.5-8.4%), and increased the risk of all-cause (hazard ratio 1.41; 95% CI 1.06-1.86) and coronary heart disease mortality (hazard ratio 2.44; 95% CI 1.11-5.37) compared with HbA(1c) of 48 mmol/mol (6.5%) or less. Analysis of HbA(1c) as a continuous variable showed that every XX mmol/mol (1%) increase in HbA(1c) decreased stroke mortality risk by 51% in those with HbA(1c) level less than 48 mmol/mol (6.5%) and increased stroke mortality risk by 30% in those with an HbA(1c) level of 48 mmol/mol (6.5%) or higher, suggesting a U-shaped association between HbA(1c) and stroke mortality.

CONCLUSION

High HbA(1c) predicted excess risk of all-cause, cardiovascular disease, coronary heart disease and stroke mortality. The question of whether low HbA(1c) increases mortality in older patients with diabetes needs further investigation.

Glycated hemoglobin and associated risk factors in older adults

BACKGROUND

The aim of this study is to investigate the relationships between HbA1c and other risk factors like obesity, functional fitness, lipid profile, and inflammatory status in older adults. Epidemiological evidence suggests that HbA1c is associated with cardiovascular and ischemic heart disease risk. Excess of body weight and obesity are considered to play a central role in the development of these conditions. Age is associated with several risk factors as increased body fat and abdominal fat, deterioration of the lipid profile, diabetes, raising in inflammatory activity, or decreased functional fitness.

METHODS

Data were available from 118 participants aged 65-95 years, including 72 women and 46 men. Anthropometric variables were taken, as was functional fitness, blood pressure and heart rate. Blood samples were collected after 12 h fasting, and HbA1c, hs-CRP, TG, TC, HDL-C, LDL-C, and glycaemia were calculated. Bivariate and partial correlations were performed to explore associations amongst the variables of interest. Differences between groups were explored by performing factorial analysis of variance.

RESULTS

HbA1c levels ranged from 4.6%-9.4% with 93% of the cases below 6.5%. Women had higher HbA1c, glycaemia, TC, BMI, and lower and upper flexibility than men. Men had higher BW, WC, 6-min walking distance, and VO2peak than women. Age, SBP, DBP, HRrest, HRpeak, HDL-C, LDL-C, TG, TG/HDL-C ratio, Log10 hs-CRP, upper and lower strength, and agility and dynamic balance were similar in men and women. HbA1c had positive associations with glycaemia, HDL-C, TG/HDL-C, BW, WC, BMI, but not with functional fitness, TC, LDL-C, Log10 hs-CRP, PAD, or PAS. Obese participants had higher HbA1c than non-obese only when IDF and not USDHHS criteria were applied.

CONCLUSIONS

Older women had higher HbA1c than men, even after controlling for BMI. HbA1c associates equally with BW, BMI or WC. Population-based criteria are recommended to classify obesity and to identify higher levels of HbA1c in obese older adults. HbA1c associates with atherogenic dyslipidemia particularly with TG and TG/HDL-C ratio, but not with TC, HDL-C, or LDL-C. HbA1c is not associated with hs-CRP, and with functional fitness and aerobic endurance.

Relationship between hemoglobin A1c and cardiovascular disease in mild-to-moderate hypercholesterolemic Japanese individuals: subanalysis of a large-scale randomized controlled trial

Background

Although the ADA/EASD/IDF International Expert Committee recommends using hemoglobin A1c (HbA1c) to define diabetes, the relation between HbA1c and cardiovascular disease (CVD) has not been thoroughly investigated. We analyzed this relation using clinical data on Japanese individuals with hypercholesterolemia.

Methods

In the large-scale MEGA Study 7832 patients aged 40 to 70 years old with mild-to-moderate hypercholesterolemia without CVD were randomized to diet alone or diet plus pravastatin and followed for >5 years. In the present subanalysis of that study a total of 4002 patients with baseline and follow-up HbA1c data were stratified according to having an average HbA1c during the first year of follow-up <6.0%, 6.0%-<6.5%, or ≥6.5% and their subsequent 5-year incidence rates of CVD compared according to sex, low-density lipoprotein cholesterol (LDL-C), and treatment arm.

Results

Overall, risk of CVD was significantly 2.4 times higher in individuals with HbA1c ≥6.5% versus <6.0%. A similar relation was noted in men and women (hazard ratio [HR], 2.1; p <0.01 and HR, 3.0; p <0.01, respectively) and was regardless of treatment arm (diet alone group: HR, 2.2; p <0.001; diet plus pravastatin group: HR, 1.8; p = 0.02). Spline curves showed a continuous risk increase according to HbA1c level in all subpopulations studied.

Conclusions

In hypercholesterolemic individuals the risk of CVD increases linearly with HbA1c level. This significant contribution by elevated HbA1c to increased CVD is independent of pravastatin therapy, and thus requires appropriate HbA1c management in addition to lipids reduction.

Haemoglobin A1c levels and subsequent cardiovascular disease in persons without diabetes: a meta-analysis of prospective cohorts

AIMS/HYPOTHESIS

The aim of this meta-analysis was to determine the relationship between HbA(1c) levels and subsequent cardiovascular outcomes in individuals without diabetes.

METHODS

We searched Medline, Embase and Scopus from initiation of the study until the end of 2009. One reviewer searched and another verified findings. Data were extracted by one reviewer and verified by another. We accepted prospective studies in any language reporting three or more quartiles for HbA(1c) levels. Within quartiles, authors must have presented both numbers of patient-years at risk and cardiovascular outcomes. Outcomes per person-time at risk were regressed on average HbA(1c) values using Poisson regression. We pooled β coefficients using Cochran's semi-weighted (inverse variance) random-effects model. Study quality was assessed using the Downs-Black scale.

RESULTS

We investigated 16 datasets (nine for total cardiovascular events and seven for death) from five papers with 44,158 patients (44% men) over 404,899 patient-years of follow-up. There were 1,366 cardiovascular deaths (3.1%; 3.37/1,000 person-years) and 2,142 cardiovascular events (4.9%; 5.29/1,000 person-years). The overall meta-analytic β coefficients were 0.720 (95% CI 0.307-1.133) and 0.757 (95% CI 0.382-1.132) for cardiac death and events, respectively. Compared with the baseline value of 0.0427, an HbA(1c) level of 0.05 was associated with a relative risk for cardiovascular death of 1.13 (95% CI 1.05-1.21), a 0.06 value with 1.34 (95% CI 1.13-1.58), and a 0.07 HbA(1c) with relative risk 1.58 (95% CI 1.22-2.06). Results for total cardiovascular events were similar. The average study quality was 0.7 (70%).

CONCLUSIONS/INTERPRETATION

We conclude that HbA(1c) was significantly associated with cardiovascular events and deaths in persons without diabetes.

Hyperglycaemia, microangiopathy, diabetes and dementia risk

Brain microangiopathy increases in frequency and severity with older age, with the presence of hypertension and to a lesser extent with diabetes. Magnetic resonance imaging is used to provide anatomical descriptions, but at this time only clinical examination and neuropsychological testing can assess white matter functioning. Clinical correlates of microangiopathy appear as subcortical cognitive alterations, but data are controversial about dementia risk. Brain microangiopathy seems to be however a complication of chronic hyperglycaemia, probably due to similar mechanisms occurring in retinopathy and other microvascular complications. To date, many questions have been raised: How can brain microangiopathy progression be monitored? Is there a reversible stage of brain microangiopathy? Which preventive actions should be implemented in aging patients with diabetes? Finally, what type of care should be provided for people with diabetes and mild cognitive impairment or overt dementia to slow down cognitive worsening?

Differential impact of diabetes and hypertension in the brain: adverse effects in white matter

Humans subjected to diabetes mellitus (DM) and/or hypertension (HTN) develop cognitive decline, cerebral atrophy and white matter abnormalities, but the relative effects of DM and HTN upon myelin and axonal integrity is unknown. We studied models of Type 1 (streptozotocin-induced) and Type 2 DM (ZDF) ± HTN (ZSF-1, SHR) in adult rats using magnetic resonance imaging (MRI) and structural and molecular techniques. Type 1 or 2 DM independently led to loss of myelin associated with changes with MRI T2 and magnetization tensor ratios throughout white matter regions. HTN's effect on myelin loss was minimal. Loss of oligodendroglia and myelin proteins was only identified in either Type 1 or Type 2 DM. Activation of the signal transduction pathways initiated by the receptor for advanced glycation end products (AGEs), RAGE, including upregulation of the signal transducer nuclear factor (NF) κB only occurred with DM. Diabetes is a greater contributor to white matter loss than hypertension in the rat brain, while hypertension only plays a mild additive effect upon neurodegeneration in the presence of diabetes.

Vascular health, diabetes, APOE and dementia: the Aging, Demographics, and Memory Study

INTRODUCTION

Evidence from clinical samples and geographically limited population studies suggests that vascular health, diabetes and apolipoprotein epsilon4 (APOE) are associated with dementia.

METHODS

A population-based sample of 856 individuals aged 71 years or older from all contiguous regions of the United States received an extensive in-home clinical and neuropsychological assessment in 2001-2003. The relation of hypertension, diabetes, heart disease, stroke, medication usage, and APOE epsilon4 to dementia was modelled using adjusted multivariable logistic regression.

RESULTS

Treated stroke (odds ratio [OR] 3.8, 95% confidence interval [CI] 2.0, 7.2), untreated stroke (OR 3.5, 95% CI 1.7, 7.3), and APOE epsilon4 (OR 2.8, 95% CI 1.7, 4.5) all increased the odds of dementia. Treated hypertension was associated with lower odds of dementia (OR 0.5, 95% CI 0.3, 1.0). Diabetes and heart disease were not significantly associated with dementia. A significant interaction was observed between APOE epsilon4 and stroke (P = 0.001).

CONCLUSIONS

Data from the first dementia study that is representative of the United States population suggest that stroke, the APOE epsilon4 allele and their interaction are strongly associated with dementia.

Diabetes mellitus and geriatric syndromes

Diabetes mellitus is associated with an increased prevalence and incidence of geriatric syndrome: functional disabilities, depression, fall, urinary incontinence, malnutrition and cognitive impairment. Geriatric syndrome not only leads to frailty, loss of independence and low quality of life, but also becomes a major obstacle in the treatment and care of diabetic people. The risk factors or contributing factors of geriatric symptoms are micro- and macrovascular complications, age-rated comorbid disease and aging per se. Comprehensive geriatric assessment of geriatric syndrome, including basic activities of daily living, instrumental activities of daily living, gait and balance, visual acuity, the Mini-Mental State Examination, depression scores, history and risk of fall, urination and nutrition, should be performed as part of the care of elderly diabetic patients, in particular old-old patients. Because geriatric syndromes are multifactorial and share risk factors, diabetic people with any geriatric symptoms should be treated with a common concentric strategy, such as supervised exercise therapy including muscle-strengthening training, psychological support, social support for adherence, and good glycemic control with avoidance of hypoglycemia.

Uncontrolled diabetes increases the risk of Alzheimer's disease: a population-based cohort study

AIMS/HYPOTHESIS

Diabetes has been related to Alzheimer's disease with inconsistent findings. We aimed to clarify the association of diabetes with different dementing disorders taking into account glycaemic control, and to explore the link between glucose dysregulation and neurodegeneration.

METHODS

A dementia-free cohort (n = 1,248) aged >or=75 years was longitudinally examined to detect dementia, Alzheimer's disease and vascular dementia (VaD) cases (Diagnostic and Statistical Manual of Mental Disorders, revised third edition [DSM-III-R] criteria). The Alzheimer's disease diagnoses were subdivided into Alzheimer's disease with stroke and Alzheimer's disease without hypertension, heart disease and stroke. Diabetes was ascertained based on medical history, or hypoglycaemic medication use, or a random blood glucose level >or=11.0 mmol/l, which included undiagnosed diabetes when neither a history of diabetes nor hypoglycaemic drugs use was present. Uncontrolled diabetes was classified as a random blood glucose level >or=11.0 mmol/l in diabetic patients. Borderline diabetes was defined as a random blood glucose level of 7.8-11.0 mmol/l in diabetes-free individuals. Cox models were used to estimate HRs.

RESULTS

During the 9 year follow-up, 420 individuals developed dementia, including 47 with VaD and 320 with Alzheimer's disease (of the 320 Alzheimer's disease cases, 78 had previous, temporally unrelated stroke, and 137 had no major vascular comorbidities). Overall diabetes was only related to VaD (HR 3.21, 95% CI 1.20-8.63). Undiagnosed diabetes led to an HR of 3.29 (95% CI 1.20-9.01) for Alzheimer's disease. Diabetic patients with random blood glucose levels <7.8 mmol/l showed no increased dementia risk. Uncontrolled and borderline diabetes were further associated with Alzheimer's disease without vascular comorbidities.

CONCLUSIONS/INTERPRETATION

Uncontrolled diabetes increases the risk of Alzheimer's disease and VaD. Our findings suggest a direct link between glucose dysregulation and neurodegeneration.

Continuous relationships between non-diabetic hyperglycaemia and both cardiovascular disease and all-cause mortality: the Australian Diabetes, Obesity, and Lifestyle (AusDiab) study

AIMS/HYPOTHESIS

Hyperglycaemia is a risk factor for cardiovascular disease (CVD) and all-cause mortality in individuals without diabetes. We investigated: (1) whether the risk of all-cause and CVD mortality extended continuously throughout the range of fasting plasma glucose (FPG), 2 h plasma glucose (2hPG) and HbA(1c) values; and (2) the ability of these measures to improve risk prediction for mortality.

METHODS

Data on 10,026 people aged >or=25 years without diagnosed diabetes were obtained from the population-based Australian Diabetes, Obesity and Lifestyle study. Between 1999 and 2000, FPG, 2hPG and HbA(1c) were assessed and all-cause (332 deaths) and CVD (88 deaths) mortality were obtained after 7 years.

RESULTS

Both 2hPG and HbA(1c) exhibited linear relationships with all-cause and CVD mortality, whereas FPG showed J-shaped relationships. The adjusted HR (95% CI) for all-cause mortality per SD increase was 1.2 (1.1-1.3) for 2hPG and 1.1 (1.0-1.2) for HbA(1c). The HR for FPG <5.1 mmol/l (per SD decrease) was 2.0 (1.3-3.0); for FPG >or=5.1 mmol/l (per SD increase) the HR was 1.1 (1.0-1.2). Corresponding HRs for CVD mortality were 1.2 (1.0-1.4), 1.2 (1.0-1.3), 4.0 (2.1-7.6) and 1.3 (1.1-1.4). The discriminative ability of each measure was similar; no measure substantially improved individual risk identification over traditional risk factors.

CONCLUSIONS/INTERPRETATION

In individuals without diagnosed diabetes, 2hPG and FPG, but not HbA(1c) were significant predictors of all-cause mortality, whereas all measures were significant predictors of CVD mortality. However, these glucose measures did not substantially improve individual risk identification.