Glucose intolerance and diabetes as risk factors for cognitive impairment in people at high cardiovascular risk: results from the ONTARGET/TRANSCEND research programme

Angiotensin-converting-enzyme inhibitors and angiotensin receptor blockers for preventing the progression of diabetic kidney disease

BACKGROUND

Guidelines suggest that adults with diabetes and kidney disease receive treatment with angiotensin-converting-enzyme inhibitors (ACEi) or angiotensin receptor blockers (ARB). This is an update of a Cochrane review published in 2006.

OBJECTIVES

We compared the efficacy and safety of ACEi and ARB therapy (either as monotherapy or in combination) on cardiovascular and kidney outcomes in adults with diabetes and kidney disease.

SEARCH METHODS

We searched the Cochrane Kidney and Transplants Register of Studies to 17 March 2024 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal, and ClinicalTrials.gov.

SELECTION CRITERIA

We included studies evaluating ACEi or ARB alone or in combination, compared to each other, placebo or no treatment in people with diabetes and kidney disease.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the risk of bias and extracted data. Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratios (RR) and their 95% confidence intervals (CI) for dichotomous outcomes and mean difference (MD) or standardised mean difference (SMD) and 95% CI for continuous outcomes. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

One hundred and nine studies (28,341 randomised participants) were eligible for inclusion. Overall, the risk of bias was high. Compared to placebo or no treatment, ACEi may make little or no difference to all-cause death (24 studies, 7413 participants: RR 0.91, 95% CI 0.73 to 1.15; I2 = 23%; low certainty) and with similar withdrawals from treatment (7 studies, 5306 participants: RR 1.03, 95% CI 0.90 to 1.19; I2 = 0%; low certainty). ACEi may prevent kidney failure (8 studies, 6643 participants: RR 0.61, 95% CI 0.39 to 0.94; I2 = 0%; low certainty). Compared to placebo or no treatment, ARB may make little or no difference to all-cause death (11 studies, 4260 participants: RR 0.99, 95% CI 0.85 to 1.16; I2 = 0%; low certainty). ARB have uncertain effects on withdrawal from treatment (3 studies, 721 participants: RR 0.85, 95% CI 0.58 to 1.26; I2 = 2%; low certainty) and cardiovascular death (6 studies, 878 participants: RR 3.36, 95% CI 0.93 to 12.07; low certainty). ARB may prevent kidney failure (3 studies, 3227 participants: RR 0.82, 95% CI 0.72 to 0.94; I2 = 0%; low certainty), doubling of serum creatinine (SCr) (4 studies, 3280 participants: RR 0.84, 95% CI 0.72 to 0.97; I2 = 32%; low certainty), and the progression from microalbuminuria to macroalbuminuria (5 studies, 815 participants: RR 0.44, 95% CI 0.23 to 0.85; I2 = 74%; low certainty). Compared to ACEi, ARB had uncertain effects on all-cause death (15 studies, 1739 participants: RR 1.13, 95% CI 0.68 to 1.88; I2 = 0%; low certainty), withdrawal from treatment (6 studies, 612 participants: RR 0.91, 95% CI 0.65 to 1.28; I2 = 0%; low certainty), cardiovascular death (13 studies, 1606 participants: RR 1.15, 95% CI 0.45 to 2.98; I2 = 0%; low certainty), kidney failure (3 studies, 837 participants: RR 0.56, 95% CI 0.29 to 1.07; I2 = 0%; low certainty), and doubling of SCr (2 studies, 767 participants: RR 0.88, 95% CI 0.52 to 1.48; I2 = 0%; low certainty). Compared to ACEi plus ARB, ACEi alone has uncertain effects on all-cause death (6 studies, 1166 participants: RR 1.08, 95% CI 0.49 to 2.40; I2 = 20%; low certainty), withdrawal from treatment (2 studies, 172 participants: RR 0.78, 95% CI 0.33 to 1.86; I2 = 0%; low certainty), cardiovascular death (4 studies, 994 participants: RR 3.02, 95% CI 0.61 to 14.85; low certainty), kidney failure (3 studies, 880 participants: RR 1.36, 95% CI 0.79 to 2.32; I2 = 0%; low certainty), and doubling of SCr (2 studies, 813 participants: RR 1.14, 95% CI 0.70 to 1.85; I2 = 0%; low certainty). Compared to ACEi plus ARB, ARB alone has uncertain effects on all-cause death (7 studies, 2607 participants: RR 1.02, 95% CI 0.76 to 1.37; I2 = 0%; low certainty), withdrawn from treatment (3 studies, 1615 participants: RR 0.81, 95% CI 0.53 to 1.24; I2 = 0%; low certainty), cardiovascular death (4 studies, 992 participants: RR 3.03, 95% CI 0.62 to 14.93; low certainty), kidney failure (4 studies, 2321 participants: RR 1.15, 95% CI 0.67 to 1.95; I2 = 29%; low certainty), and doubling of SCr (3 studies, 2252 participants: RR 1.18, 95% CI 0.85 to 1.64; I2 = 0%; low certainty). Comparative effects of different ACEi or ARB and low-dose versus high-dose ARB were rarely evaluated. No study compared different doses of ACEi. Adverse events of ACEi and ARB were rarely reported.

AUTHORS' CONCLUSIONS

ACEi or ARB may make little or no difference to all-cause and cardiovascular death compared to placebo or no treatment in people with diabetes and kidney disease but may prevent kidney failure. ARB may prevent the doubling of SCr and the progression from microalbuminuria to macroalbuminuria compared with a placebo or no treatment. Despite the international guidelines suggesting not combining ACEi and ARB treatment, the effects of ACEi or ARB monotherapy compared to dual therapy have not been adequately assessed. The limited data availability and the low quality of the included studies prevented the assessment of the benefits and harms of ACEi or ARB in people with diabetes and kidney disease. Low and very low certainty evidence indicates that it is possible that further studies might provide different results.

Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers for adults with early (stage 1 to 3) non-diabetic chronic kidney disease

BACKGROUND

Chronic kidney disease (CKD) is a long-term condition that occurs as a result of damage to the kidneys. Early recognition of CKD is becoming increasingly common due to widespread laboratory estimated glomerular filtration rate (eGFR) reporting, raised clinical awareness, and international adoption of the Kidney Disease Improving Global Outcomes (KDIGO) classifications. Early recognition and management of CKD affords the opportunity to prepare for progressive kidney impairment and impending kidney replacement therapy and for intervention to reduce the risk of progression and cardiovascular disease. Angiotensin-converting enzyme inhibitors (ACEi) and angiotensin receptor blockers (ARB) are two classes of antihypertensive drugs that act on the renin-angiotensin-aldosterone system. Beneficial effects of ACEi and ARB on kidney outcomes and survival in people with a wide range of severity of kidney impairment have been reported; however, their effectiveness in the subgroup of people with early CKD (stage 1 to 3) is less certain. This is an update of a review that was last published in 2011.

OBJECTIVES

To evaluate the benefits and harms of ACEi and ARB or both in the management of people with early (stage 1 to 3) CKD who do not have diabetes mellitus (DM).

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 6 July 2023 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and Embase, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal, and ClinicalTrials.gov.

SELECTION CRITERIA

Randomised controlled trials (RCTs) reporting the effect of ACEi or ARB in people with early (stage 1 to 3) CKD who did not have DM were selected for inclusion. Only studies of at least four weeks duration were selected. Authors independently assessed the retrieved titles and abstracts and, where necessary, the full text to determine which satisfied the inclusion criteria.

DATA COLLECTION AND ANALYSIS

Data extraction was carried out by two authors independently, using a standard data extraction form. The methodological quality of included studies was assessed using the Cochrane risk of bias tool. Data entry was carried out by one author and cross-checked by another. When more than one study reported similar outcomes, data were pooled using the random-effects model. Heterogeneity was analysed using a Chi² test and the I² test. Results were expressed as risk ratios (RR) and their 95% confidence intervals (CI) for dichotomous outcomes and mean difference (MD) and 95% CI for continuous outcomes. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach MAIN RESULTS: Six studies randomising 9379 participants with CKD stages 1 to 3 (without DM) met our inclusion criteria. Participants were adults with hypertension; 79% were male from China, Europe, Japan, and the USA. Treatment periods ranged from 12 weeks to three years. Overall, studies were judged to be at unclear or high risk of bias across all domains, and the quality of the evidence was poor, with GRADE rated as low or very low certainty. In low certainty evidence, ACEi (benazepril 10 mg or trandolapril 2 mg) compared to placebo may make little or no difference to death (any cause) (2 studies, 8873 participants): RR 2.00, 95% CI 0.26 to 15.37; I² = 76%), total cardiovascular events (2 studies, 8873 participants): RR 0.97, 95% CI 0.90 to 1.05; I² = 0%), cardiovascular-related death (2 studies, 8873 participants): RR 1.73, 95% CI 0.26 to 11.66; I² = 54%), stroke (2 studies, 8873 participants): RR 0.76, 95% CI 0.56 to 1.03; I² = 0%), myocardial infarction (2 studies, 8873 participants): RR 1.00, 95% CI 0.84 to 1.20; I² = 0%), and adverse events (2 studies, 8873 participants): RR 1.33, 95% CI 1.26 to 1.41; I² = 0%). It is uncertain whether ACEi (benazepril 10 mg or trandolapril 2 mg) compared to placebo reduces congestive heart failure (1 study, 8290 participants): RR 0.75, 95% CI 0.59 to 0.95) or transient ischaemic attack (1 study, 583 participants): RR 0.94, 95% CI 0.06 to 15.01; I² = 0%) because the certainty of the evidence is very low. It is uncertain whether ARB (losartan 50 mg) compared to placebo (1 study, 226 participants) reduces: death (any-cause) (no events), adverse events (RR 19.34, 95% CI 1.14 to 328.30), eGFR rate of decline (MD 5.00 mL/min/1.73 m2, 95% CI 3.03 to 6.97), presence of proteinuria (MD -0.65 g/24 hours, 95% CI -0.78 to -0.52), systolic blood pressure (MD -0.80 mm Hg, 95% CI -3.89 to 2.29), or diastolic blood pressure (MD -1.10 mm Hg, 95% CI -3.29 to 1.09) because the certainty of the evidence is very low. It is uncertain whether ACEi (enalapril 20 mg, perindopril 2 mg or trandolapril 1 mg) compared to ARB (olmesartan 20 mg, losartan 25 mg or candesartan 4 mg) (1 study, 26 participants) reduces: proteinuria (MD -0.40, 95% CI -0.60 to -0.20), systolic blood pressure (MD -3.00 mm Hg, 95% CI -6.08 to 0.08) or diastolic blood pressure (MD -1.00 mm Hg, 95% CI -3.31 to 1.31) because the certainty of the evidence is very low.

AUTHORS' CONCLUSIONS

There is currently insufficient evidence to determine the effectiveness of ACEi or ARB in patients with stage 1 to 3 CKD who do not have DM. The available evidence is overall of very low certainty and high risk of bias. We have identified an area of large uncertainty for a group of patients who account for most of those diagnosed as having CKD.

Based on voxel-based morphological analysis to investigate the effect of acupuncture-rehabilitation therapy on hippocampal volume and its neuroprotective mechanism in patients with vascular cognitive impairment with type 2 diabetes mellitus: A study protocol

BACKGROUND

Vascular cognitive impairment (VCI) has a decline in the ability of learning, memory, understanding and execution, which seriously interferes with the daily life of patients. Type 2 diabetes mellitus (T2DM) is an important risk factor for VCI. In recent years, the pathogenesis and treatment of VCI with T2DM have become a research hotspot. Acupuncture-rehabilitation therapy plays an important role in the treatment of various functional disorders of cerebrovascular diseases. In the previous study of the research group, it has been proved from the perspective of imaging that acupuncture-rehabilitation therapy can improve the cognitive function of patients with ischemic stroke. Based on the previous research results, we speculate that acupuncture-rehabilitation therapy not only improves the function of cognitive-related brain regions, but also affects its structure, as well as serum biomarkers highly related to T2DM and cognitive function.

METHODS/DESIGN

A partial randomized controlled trial will be conducted at the Second Affiliated Hospital of Heilongjiang University of Chinese Medicine, between July 1, 2021 and December 31, 2023. A total of 80 subjects will participate in the trial, including 25 healthy volunteers, 25 T2DM patients with normal cognitive function and 30 VCI patients with T2DM. They will all have at least 1 functional magnetic resonance imaging scan. Through the calculation and analysis of voxel-based morphological analysis indexes, the changes of hippocampal volume and function in the 3 groups are compared, so as to confirm the correlation between hippocampal structural and functional changes, between T2DM patients and healthy volunteers, as well as T2DM patients with normal cognitive and VCI patients with T2DM. Then the VCI patients with T2DM were randomly divided into 2 groups. The control group was given routine drug treatment to control blood sugar and improve cognitive function, and the experimental group was treated with acupuncture-rehabilitation therapy on the basis of the control group. Patients in both groups will receive serum biomarkers (superoxide organic dismutase, maleic dialdehyde, brain-derived neurotrophic factor) detection and neuropsychological scale (Montreal Cognitive Assessment, Webster Memory Scale IV Chinese version (adult version), functional independent measurement) evaluation before treatment, 4 weeks, 8 weeks, and 12 weeks after treatment. The functional magnetic resonance imaging scan will be performed again after 12 weeks of treatment. To observe the effect of acupuncture-rehabilitation therapy on cognitive function of VCI patients with T2DM.

DISCUSSION

This trial can clarify the effect of acupuncture-rehabilitation therapy on hippocampal volume and its intervention mechanism on oxidative stress injury in VCI patients with T2DM, and clarify the scientific connotation of its neuroprotective mechanism in the VCI patients with T2DM, in order to provide a theoretical basis for the clinical application of acupuncture-rehabilitation therapy in the treatment of VCI.

TRIAL REGISTRATION

Chinese Clinical Trial Registry (ChiCTR), ChiCTR2100047803. Registered 26 June, https://www.chictr.org.cn/showproj.aspx?proj=128707.

Pre-diabetes and diabetes are independently associated with adverse cognitive test results: a cross-sectional, population-based study

BACKGROUND

Diabetes is a risk factor for cognitive impairment, but whether there is also a link between pre-diabetes and cognitive dysfunction is not yet fully established. The aim of this observational study was to investigate associations between pre-diabetes/diabetes and cognitive test results, and also between glucose levels measured during the Oral Glucose Tolerance Test (OGTT) and cognitive outcomes.

METHODS

During 2007-2012, in all 2994 people (mean age 72 years), residing in Malmö, Sweden, underwent a clinical examination including the OGTT, cardiovascular measurements including carotid-femoral pulse wave velocity (c-f PWV) and two cognitive tests, the Mini Mental State Examination (MMSE), measuring global cognitive function, and A Quick Test of Cognitive Speed (AQT), measuring processing speed and executive functioning. Regression analyses were performed to investigate associations between: (a) categories of normal or impaired glucose metabolism, and (b) OGTT measurements, respectively, as exposure variables and cognitive test results as outcomes. Adjustments were made for demographics, lifestyle factors and cardiovascular risk factors.

RESULTS

Participants with pre-diabetes and diabetes scored slightly worse cognitive test results compared to the control group. Results of participants with a long disease duration of diabetes since the baseline examination 13 years earlier were poorer (mean AQT test time 17.8 s slower than controls, p < 0.001). Linear associations were found between fasting and 2-h glucose and cognitive outcomes in the whole population, but also in a sub-analysis including only individuals without diabetes (for 2-h glucose and MMSE results: B = - 2.961, p = 0.005). Associations were stronger for older or less physically active individuals. When adjusting for cardiovascular risk factors, most correlations were non-significant.

CONCLUSIONS

Pre-diabetes and diabetes are associated with minor deficits in global cognitive function, processing speed and executive functioning. Long-standing diabetes is associated with bigger deficits. There appears to be a continuous inverse correlation between glucose levels and cognitive test results, also for people without diabetes. Associations are stronger in older and less physically active individuals. Cardiovascular factors are important mediating factors in the pathway between diabetes and cognitive dysfunction.

Altered functional connectivity of the default mode network by glucose loading in young, healthy participants

Background

The functional connectivity of the default mode network (DMN) decreases in patients with Alzheimer’s disease (AD) as well as in patients with type 2 diabetes mellitus (T2DM). Altered functional connectivity of the DMN is associated with cognitive impairment. T2DM is a known cause of cognitive dysfunction and dementia in the elderly, and studies have established that T2DM is a risk factor for AD. In addition, recent studies with positron emission tomography demonstrated that increased plasma glucose levels decrease neuronal activity, especially in the precuneus/posterior cingulate cortex (PC/PCC), which is the functional core of the DMN. These findings prompt the question of how increased plasma glucose levels decrease neuronal activity in the PC/PCC. Given the association among DMN, AD, and T2DM, we hypothesized that increased plasma glucose levels decrease the DMN functional connectivity, thus possibly reducing PC/PCC neuronal activity. We conducted this study to test this hypothesis.

Results

Twelve young, healthy participants without T2DM and insulin resistance were enrolled in this study. Each participant underwent resting-state functional magnetic resonance imaging in both fasting and glucose loading conditions to evaluate the DMN functional connectivity. The results showed that the DMN functional connectivity in the PC/PCC was significantly lower in the glucose loading condition than in the fasting condition (P = 0.014).

Conclusions

Together with previous findings, the present results suggest that decreased functional connectivity of the DMN is possibly responsible for reduced PC/PCC neuronal activity in healthy individuals with increased plasma glucose levels.

Effects of glucose, insulin, and insulin resistance on cerebral 18F-FDG distribution in cognitively normal older subjects

Background

Increasing plasma glucose levels and insulin resistance can alter the distribution pattern of fluorine-18-labeled fluorodeoxyglucose (¹⁸F-FDG) in the brain and relatively reduce ¹⁸F-FDG uptake in Alzheimer's disease (AD)-related hypometabolic regions, leading to the appearance of an AD-like pattern. However, its relationship with plasma insulin levels is unclear. We aimed to compare the effects of plasma glucose levels, plasma insulin levels and insulin resistance on the appearance of the AD-like pattern in ¹⁸F-FDG images.

Methods

Fifty-nine cognitively normal older subjects (age = 75.7 ± 6.4 years) underwent ¹⁸F-FDG positron emission tomography along with measurement of plasma glucose and insulin levels. As an index of insulin resistance, the Homeostasis model assessment of Insulin Resistance (HOMA-IR) was calculated.

Results

Plasma glucose levels, plasma insulin levels, and HOMA-IR were 102.2 ± 8.1 mg/dL, 4.1 ± 1.9 μU/mL, and 1.0 ± 0.5, respectively. Whole-brain voxelwise analysis showed a negative correlation of ¹⁸F-FDG uptake with plasma glucose levels in the precuneus and lateral parietotemporal regions (cluster-corrected p < 0.05), and no correlation with plasma insulin levels or HOMA-IR. In the significant cluster, ¹⁸F-FDG uptake decreased by approximately 4–5% when plasma glucose levels increased by 20 mg/dL. In the precuneus region, volume-of-interest analysis confirmed a negative correlation of ¹⁸F-FDG uptake with plasma glucose levels (r = -0.376, p = 0.002), and no correlation with plasma insulin levels (r = 0.156, p = 0.12) or HOMA-IR (r = 0.096, p = 0.24).

Conclusion

This study suggests that, of the three parameters, plasma glucose levels have the greatest effect on the appearance of the AD-like pattern in ¹⁸F-FDG images.

Metabolic parameters and cognitive function in a cohort of older diabetic patients

BACKGROUND

Dementia is one of the most disabling conditions associated with old age. With increasing life expectancy, prevalence of both dementia and diabetes is rising. The complex pathological relationship between diabetes mellitus (DM) and dementia has been studied, but is not yet fully understood.

AIMS

The main objective of this study was to investigate the relationship between metabolic parameters and the cognitive function in older diabetics.

METHODS

A total number of 360 diabetic subjects, age 65 years and over, and 300 older people controls were included. Clinical and biological parameters, together with the cognitive function, were assessed every 6 months over a 18-month period, for each study participant.

RESULTS

By employing a multivariate linear regression analysis, several significant relationships have been identified: between Clock Drawing Test (CDT) scores and HbA1c (R ² = 0.68); between CDT scores (R ² = 0.51) and overall MMSE scores (R ² = 0.43) on one hand, and DM duration in years, on the other hand; also between CDT scores and BMI (R ² = 0.59). There was no significant association between fasting serum glucose (FSG), total serum cholesterol, LDL cholesterol or triglycerides levels and cognitive function scores (p > 0.05).

CONCLUSIONS

The close detailed monitoring of the cognitive function and a rigorous metabolic control are important, especially in the very early stages of DM. Addressing factors such as weight control in older diabetic patients could contribute to better cognitive outcomes.

Diabetes and brain health: implications for practice

BACKGROUND

It is widely accepted that people with mental illness have increased risk of cardiometabolic complications such as obesity and type 2 diabetes mellitus. What is less well known is that individuals with diabetes have an increased risk of brain health complications including depression, cognitive impairment and dementia. These conditions can adversely influence disease self-management and further increase risk of other diabetes complications. Aim The aim of this paper is to highlight the increased risk of brain health complications in populations with diabetes in order to promote awareness of such complications among healthcare professionals and encourage timely intervention.

METHODS

An overview of the prevalence and potential mechanisms linking depression and cognitive impairment with diabetes as well as implications for detection, management and brain health protection, based on a narrative review of the literature.

CONCLUSIONS

Early detection and effective management of depression and cognitive impairment among individuals with diabetes has the potential to minimise adverse health outcomes. In order to promote screening healthcare professionals caring for individuals with diabetes in all settings must be aware of the increased risk of brain health complications in this vulnerable population.

Central and peripheral pathogenetic forms of type 2 diabetes: a proof-of-concept study

HYPOTHESIS

Previous studies provide evidence that glycated haemoglobin (HbA1c) and fasting plasma glucose (FPG) should not be considered as interchangeable alternatives in the diagnosis of the same type 2 diabetes, but as indicators of its different pathogenetic subtypes. This study was conducted to determine whether a particularly high amount of glucose in either HbA1c form or in fasting plasma would be found in diabetic patients genetically predisposed for either intensive cognitive or intensive muscle metabolic activity, respectively.

METHODS

HbA1c and FPG levels, polymorphisms of genes indicating the predisposition to different cognitive activity (the dopamine D2 receptor (DRD2/ANKK1)), muscle activity (peroxisome proliferator-activated receptor gamma, coactivator 1 alpha (PGC1A(PPARGC1A))), and vascular regulation of general metabolic activity (the angiotensin 1 converting enzyme (ACE)) were assessed in diabetic patients and nondiabetic controls.

RESULTS

DRD2/ANKK1 polymorphism that affects baseline central arousal determined HbA1c variations uncorrelated with FPG in total and clinical groups. The mutation of PGC1A mainly affecting peripheral glucose metabolism had an effect on FPG correlated or uncorrelated with HbA1c depending on the effect assessment in the total sample or in the nondiabetic group, respectively. ACE insertion/deletion (I/D) gene polymorphism was associated with both HbA1c and FPG fluctuations, but only in diabetic patients.

CONCLUSION

The findings provide evidence that the HbA1c and FPG may predict the risks for different subtypes of type 2 diabetes associated with either brain or muscle metabolic activity in genetically vulnerable people.

Prediabetes and associated disorders

Prediabetes represents an elevation of plasma glucose above the normal range but below that of clinical diabetes. Prediabetes includes individuals with IFG, IGT, IFG with IGT and elevated HbA1c levels. Insulin resistance and β-cell dysfunction are characteristic of this disorder. The diagnosis of prediabetesis is vital as both IFG and IGT are indeed well-known risk factors for type 2 diabetes with a greater risk in the presence of combined IFG and IGT. Furthermore, as will be illustrated in this review, prediabetes is associated with associated disorders typically only considered in with established diabetes. These include cardiovascular disease, periodontal disease, cognitive dysfunction, microvascular disease, blood pressure abnormalities, obstructive sleep apnea, low testosterone, metabolic syndrome, various biomarkers, fatty liver disease, and cancer. As the vast majority of individuals with prediabetes are unaware of their diagnosis, it is therefore vital that the associated conditions are identified, particularly in the presence of mild hyperglycemia, so they may benefit from early intervention.

Diabetes, dysglycemia and cognitive dysfunction

Evidence from the last decade supports the hypothesis that diabetes may be viewed as a disease of accelerated cognitive ageing. It is a risk factor for the development of dementia, for an accelerated rate of cognitive decline and for cognitive dysfunction. Thus, 'diabetes-related cognitive dysfunction' may be viewed as another long-term complication of diabetes. This article will review the evidence supporting this hypothesis and will elaborate on the implications for patient care, as well as discuss potential treatment options and their limitation. The final section reviews possible mechanistic explanations.

Depression, anxiety, cognitive impairment and their association with clinical and demographic variables in people with type 2 diabetes: a 4-year prospective study

OBJECTIVE

To investigate depression, anxiety and cognitive impairment and their associations with clinical and socio-demographic variables in type 2 diabetes.

METHODS

The Zung Self-Rating Depression-Anxiety Scale and Mini-Mental State Examination (MMSE) were administered at baseline and after 4 years to 498 consecutive patients, 249 non-insulin treated (NIT) and 249 insulin treated (IT), aged 40-80 years.

RESULTS

At baseline, IT patients were older, had longer disease duration, higher HbA1c and did more glucose monitoring (p < 0.001, all) but their depression scores were lower than among NIT (p = 0.006), with no differences for anxiety or MMSE. After 4 years, 72 patients were lost to the follow-up, of whom 18 had died. 41 NIT had switched to insulin and increased BMI (p = 0.004), blood pressure (p < 0.001), retinopathy severity (p = 0.03) and microalbuminuria (p = 0.0045), but did not change their scores for depression, anxiety or MMSE. The remaining 171 NIT improved fasting glucose (p = 0.006), total cholesterol (p < 0.0001), triglyceride (p = 0.0026) and HbA1c (p = 0.0006). Despite increased prevalence of microalbuminuria and retinopathy (p < 0.0001, both), depression (p = 0.04) and MMSE (p = 0.0007) improved. Foot ulcers (p = 0.03), retinopathy (p < 0001), microalbuminuria (p = 0.0047) and hypertension (p < 0.0001) increased in the remaining 214 IT patients, in whom depression (p = 0.0005) and anxiety (p < 0.0001) worsened while MMSE improved slightly (p = 0.0002). On multivariate analysis, depression was associated with being a woman and anxiety with diabetes duration and lower schooling, which also affected MMSE scores.

CONCLUSIONS

Depression was associated with female gender and worsening complications but not modified by diabetes duration or switching to insulin therapy. Diabetes duration and lower schooling may affect anxiety and cognitive impairment.

Dysglycaemia, vasculopenia, and the chronic consequences of diabetes

High glucose concentrations are independent risk factors for many serious disorders. Glucose lowering can reduce or prevent many of these disorders. The mechanisms that cause glucose-linked tissue damage are unclear; however, the sequence of tissue changes that lead to one of these consequences (ie, retinopathy) have been understood for decades because the retina can be easily inspected and changes in its vascular supply can easily be assessed. The possibility that the long-term harms of raised glucose concentrations are mediated through reduced capillary perfusion (ie, vasculopenia) is suggested by strong epidemiological links between capillary abnormalities in the retina and most of the complications of diabetes, a delay between the therapeutic effect of glucose lowering in the retina and in other tissues, laboratory evidence that atherosclerosis is promoted by abnormalities in the capillary-rich vasa vasorum of conductance vessels, and similarities in capillary abnormalities in the retina and the kidney of people with diabetes. These findings also suggest that the retina might be a window through which the effect of raised glucose concentrations on a wide range of tissues can be seen. If continuing research lends support to this theory, treatments that counteract the effect of glucose on capillaries such as those in the retina might ultimately also reduce other serious consequences of dysglycaemia.

Antihypertensive agents for preventing diabetic kidney disease

BACKGROUND

Various blood pressure-lowering agents, and particularly inhibitors of the renin-angiotensin system (RAS), are widely used for people with diabetes to prevent the onset of diabetic kidney disease (DKD) and adverse cardiovascular outcomes. This is an update of a Cochrane review first published in 2003 and updated in 2005.

OBJECTIVES

This systematic review aimed to assess the benefits and harms of blood pressure lowering agents in people with diabetes mellitus and a normal amount of albumin in the urine (normoalbuminuria).

SEARCH METHODS

In January 2011 we searched the Cochrane Renal Group's Specialised Register through contact with the Trials Search Co-ordinator.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing any antihypertensive agent with placebo or another agent in hypertensive or normotensive patients with diabetes and no kidney disease (albumin excretion rate < 30 mg/d) were included.

DATA COLLECTION AND ANALYSIS

Two investigators independently extracted data on kidney and other patient-relevant outcomes (all-cause mortality and serious cardiovascular events), and assessed study quality. Analysis was by a random effects model was applied to analyse results which were expressed as risk ratio (RR) and 95% confidence intervals (CI).

MAIN RESULTS

We identified 26 studies that enrolling 61,264 participants. Angiotensin-converting enzyme inhibitors (ACEi) reduced the risk of new onset of microalbuminuria, macroalbuminuria or both when compared to placebo (8 studies, 11,906 patients: RR 0.71, 95% CI 0.56 to 0.89), with similar benefits in people with and without hypertension (P = 0.74), and when compared to calcium channel blockers (5 studies, 1253 participants: RR 0.60, 95% CI 0.42 to 0.85). ACEi reduced the risk of death when compared to placebo (6 studies, 11,350 participants: RR 0.84, 95% CI 0.73 to 0.97). No effect was observed for angiotensin receptor blockers (ARB) when compared to placebo for new microalbuminuria, macroalbuminuria or both (5 studies, 7653 participants: RR 0.90, 95% CI 0.68 to 1.19) or death (5 studies, 7653 participants: RR 1.12, 95% CI 0.88 to 1.41); however, meta-regression suggested possible benefits from ARB for preventing kidney disease in high risk patients. There was a trend towards benefit from use of combined ACEi and ARB for prevention of DKD compared with ACEi alone (2 studies, 4171 participants: RR 0.88, 95% CI 0.78 to 1.00).The risk of cough was significantly increased with ACEi when compared to placebo (6 studies, 11,791 patients: RR 1.84, 95% CI 1.24 to 2.72), however there was no significant difference in the risk of headache or hyperkalaemia. There was no significant difference in the risk of cough, headache or hyperkalaemia when ARB was to placebo. On average risk of bias was judged to be either low (27% to 69%) or unclear (i.e. no information available) (8% to 73%). Blinding of participants, incomplete outcome data and selective reporting were judged to be high in 23%, 31% and 31% of studies, respectively.

AUTHORS' CONCLUSIONS

ACEi were found to prevent new onset DKD and death in normoalbuminuric people with diabetes, and could therefore be used in this population. More data are needed to clarify the role of ARB and other drug classes in preventing DKD.

A cross-sectional survey of depression, anxiety, and cognitive function in patients with type 2 diabetes

To evaluate the prevalence of depression in outpatients with type 2 diabetes and its possible correlation with anxiety, cognitive function, and clinical variables. The Zung Self-Rating Depression and Anxiety Scales and the Mini-Mental-State Examination were administered to 249 non-insulin-treated (NIT) and 249 insulin-treated (IT) outpatients with type 2 diabetes, aged 40-80, in a cross-sectional survey. Compared with a reported prevalence of 6-13% in the general population, 104 (20.9%) patients had either a score indicative of depression or were on anti-depressant medication. Assuming that medication might modify the responses to questionnaires, the latter patients were excluded from further analysis. IT patients had higher age, known duration of diabetes, HbA1c, more foot ulcers, retinopathy, microalbuminuria and practised more self-monitoring of blood glucose (P < 0.01 all) but a slightly lower mean depression score (P = 0.004) and similar anxiety or cognitive function. At multivariate analysis, depression was associated with anxiety (P < 0.001), age (P < 0.001), gender (men having lower scores than women, P = 0.042), and insulin treatment, IT patients being less depressed than NIT (P < 0.001), but none of the clinical variables. Anxiety correlated with age (P < 0.001). The association between depression and anxiety became progressively weaker with increasing age. These data confirm increased prevalence of depression in a population of patients with type 2 diabetes who did not show impaired cognitive function. The lack of correlation with disease duration, metabolic control, and complications suggests that depression may not appear/worsen with diabetes and/or its complications but rather supports suggestions that it might predate both.

Blood pressure responses to hypertension treatment and trends in cognitive function in patients with initially difficult-to-treat hypertension: a retrospective subgroup analysis of the Observational Study on Cognitive Function and SBP Reduction (OSCAR) study

The Observational Study on Cognitive Function and SBP Reduction (OSCAR) provided opportunities to examine the influence of eprosartan on trends in cognitive performance in a large population of patients with difficult-to-treat hypertension (DTTH). A total of 4649 patients diagnosed retrospectively with DTTH, defined as systolic/diastolic blood pressure (SBP/DBP) ≥140/90 mm Hg despite use of at least 3 antihypertensive drugs during the month preceding the baseline visit comprised the intention-to-treat (ITT) cohort. The patients were given eprosartan-based antihypertension therapy (EBT; 600 mg/d). Blood pressure and cognitive function parameters included significant (P<.001) differences for DTTH vs non-DTTH patients such as older age, body mass index, SBP and pulse pressure (PP), and lower Mini-Mental State Examination (MMSE) score. After EBT for 6 months, SBP/DBP in DTTH was 138.8±12.2/81.9±7.4 (ΔSBP-26±15.7; ΔDBP-11.4±9.8); PP was 57.0±10.8 (ΔPP-14.5±13.8) (all P<.001 vs baseline and non-DTTH group). A total of 2576 patients (87.4%) responded to EBT (ie, SBP <140 mm Hg and/or ΔSBP ≥15 mm Hg, or DBP <90 mm Hg and/or ΔDBP ≥10 mm Hg); 1426 DTTH patients (48.4%) achieved normalized SBP/DBP (ie, SBP <140 mm Hg and DBP <90 mm Hg). ΔPP in DTTH-isolated systolic hypertension (ISH) was -18.0±13.3 mm Hg (P=.003 vs DTTH-systolic-diastolic hypertension). End-of-EBT mean MMSE was 27.5±3.0 (P<.001 vs baseline). Blood pressure responses after EBT coincided with stabilization/improvement of MMSE in this retrospective investigation in DTTH patients. The average improvement in MMSE in DTTH patients was similar to that in non-DTTH patients. EBT effects on PP may be relevant to the evolution of MMSE in DTTH-ISH patients.

Clinical backgrounds and morbidity of cognitive impairment in elderly diabetic patients

Despite numerous reports that have linked diabetes with cognitive impairment (CI), there are few studies that have attempted to clarify the morbidity of CI among elderly diabetic patients. The Mini-Mental State Examination (MMSE) was performed on 240 diabetic patients aged 65 years or older who had no diagnosis of dementia. The MMSE scores were 28-30 (normal range) in 151 patients (63%), 24-27 (suspected CI) in 77 (32%), and ≤ 23 (definite CI) in 12 (5%). Eight of the 12 patients with MMSE scores ≤ 23 underwent further detailed examination: the final diagnosis was Alzheimer's disease (AD) (N = 5), vascular dementia (N = 2), and mixed dementia (N = 1). Among 24 of the 77 patients with MMSE scores of 24-27 who were referred for further detailed examination, the final diagnosis was early AD (N = 5), cerebrovascular disease (CVD) (N = 10), and mild CI (N = 7). Only 2 of the patients were judged as being normal. The percentage of patients with a history of CVD, the rate of diuretic use, and the serum levels of non-high-density lipoprotein cholesterol were higher, and the percentage of patients with a history of habitual alcohol consumption was lower in the low MMSE score group than in the normal MMSE score group. Among elderly diabetic patients aged 65 years or older, 5% had evident CI and 32% had suspected CI. Medical staff involved in the care of diabetic patients should be highly aware of possible CI in this patient population.

Cognitive function and risks of cardiovascular disease and hypoglycaemia in patients with type 2 diabetes: the Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation (ADVANCE) trial

AIMS/HYPOTHESIS

The relationship between cognitive function, cardiovascular disease and premature death is not well established in patients with type 2 diabetes. We assessed the effects of cognitive function in 11,140 patients with type 2 diabetes who participated in the Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation (ADVANCE) trial. Furthermore, we tested whether level of cognitive function altered the beneficial effects of the BP-lowering and glycaemic-control regimens in the trial.

METHODS

Cognitive function was assessed using the Mini Mental State Examination at baseline, and defined by scores 28-30 ('normal', n = 8,689), 24-27 ('mild dysfunction', n = 2,231) and <24 ('severe dysfunction', n = 212). Risks of major cardiovascular events, death and hypoglycaemia and interactions with treatment were assessed using Cox proportional hazards analysis.

RESULTS

Relative to normal function, both mild and severe cognitive dysfunction significantly increased the multiple-adjusted risks of major cardiovascular events (HR 1.27, 95% CI 1.11-1.46 and 1.42, 95% CI 1.01-1.99; both p < 0.05), cardiovascular death (1.41, 95% CI 1.16-1.71 and 1.56, 95% CI 0.99-2.46; both p <or= 0.05) and all-cause death (1.33, 95% CI 1.16-1.54 and 1.50, 95% CI 1.06-2.12; both p < 0.03). Severe, but not mild, cognitive dysfunction increased the risk of severe hypoglycaemia (HR 2.10, 95% CI 1.14-3.87; p = 0.018). There was no evidence of heterogeneity of treatment effects on cardiovascular outcomes in subgroups defined by cognitive function at baseline.

CONCLUSIONS/INTERPRETATION

Cognitive dysfunction is an independent predictor of clinical outcomes in patients with type 2 diabetes, but does not modify the effects of BP lowering or glucose control on the risks of major cardiovascular events.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00145925.

Regulation of intracerebral arteriolar tone by K(v) channels: effects of glucose and PKC

Voltage-gated potassium (K(v)) channels in vascular smooth muscle cells (VSMC) are critical regulators of membrane potential and vascular tone. These channels exert a hyperpolarizing influence to counteract the depolarizing effects of intraluminal pressure and vasoconstrictors. However, the contribution of K(v) channel activity to the functional regulation of cerebral (parenchymal) arterioles within the brain is not known. Thus K(v) channel properties in parenchymal arteriolar SMCs were characterized. Isolated, pressurized parenchymal arterioles and arterioles in cortical brain slices exhibited robust constriction in the presence of the K(v) channel inhibitor 4-aminopyridine (4-AP). 4-AP also decreased the amplitude of K(v) currents recorded from SMCs. The steady-state activation and inactivation properties of K(v) currents suggested that these channels are composed of K(v)1.2 and 1.5 subunits, which was confirmed by RT-PCR. K(v) channels can be regulated by extracellular glucose, which may be involved in the functional hyperemic response in the brain. Thus the effects of glucose on K(v) channel activity and arteriolar function were investigated. Elevation of glucose from 4 to 14 mM significantly decreased the peak K(v) current amplitude and constricted arterioles. Arteriolar constriction was prevented by inhibition of protein kinase C (PKC), consistent with previous studies showing enhanced PKC activity in the presence of elevated glucose. In cortical brain slices, the dilation generated by neuronal activity induced by electrical field stimulation was decreased by 54% in 14 mM glucose when compared with the dilation in 4 mM glucose. In anesthetized mice the whisker stimulation-induced increase in local cerebral blood flow was also significantly decreased in 14 mM glucose, and this effect was similarly prevented by PKC inhibition. These findings point to a critical role for K(v) channels in the regulation of intracerebral arteriolar function and suggest that changes in perivascular glucose levels could directly alter vascular diameter resulting in a modulation of local cerebral blood flow.