Alternative Measures of Hyperglycemia and Risk of Alzheimer's Disease in the Community: The Hisayama Study

Association of the Ratio of Glycoalbumin to Hemoglobin A1c With Season Change and the COVID-19 Pandemic in Patients With Type 2 Diabetes Mellitus

AIM

The main purpose of the current study was to investigate the effect of season change and the influence of the COVID-19 pandemic on the ratio of glycoalbumin to hemoglobin A1c (GA/HbA1c) in patients with type 2 diabetes.

PATIENTS AND METHODS

A total of 267 patients in whom both HbA1c and GA were measured at baseline were included in this retrospective study. GA/HbA1c was investigated for three years, 2018, 2019, and 2020 (COVID-19 pandemic period).

RESULTS

The mean values for GA/HbA1c per year in 2018, 2019, and 2020 were 2.64±0.35, 2.61±0.35, 2.64±0.39, respectively. There were no significant differences in GA/HbA1c during these years. There was a tendency toward seasonal variation in GA/HbA1c (i.e., higher in summer or autumn and lower in spring or winter).

CONCLUSION

In patients with type 2 diabetes, GA/HbA1c tended to show seasonal variation, which was not influenced by the COVID-19 pandemic.

Cognitive decline in elderly patients with type 2 diabetes is associated with glycated albumin, ratio of Glycated Albumin to glycated hemoglobin, and concentrations of inflammatory and oxidative stress markers

Objective

To investigate the correlations of cognitive function with glycated albumin (GA), the ratio of GA to glycated hemoglobin (GA/HbA1c), and the concentrations of interleukin-6 (IL-6) and superoxide dismutase (SOD) in elderly patients with type 2 diabetes mellitus (T2DM).

Methods

A total of 44 elderly T2DM patients were evaluated for cognitive function using the mini-mental state examination (MMSE) and the Montreal cognitive assessment (MoCA). Patients were then divided into two groups based on the MMSE and MoCA scores: a cognitive dysfunction group and a normal cognitive function group. The correlations of the MMSE and MoCA scores with GA/HbA1c, GA, IL-6, and SOD were analyzed. Logistic regression analysis was used to identify independent influential factors for cognitive dysfunction. The predictive value of GA and GA/HbA1c for cognitive dysfunction in elderly T2DM patients was evaluated by receiver operating characteristic (ROC) curve analysis.

Results

Among these patients, 28 had cognitive impairment. They had significantly higher GA/HbA1c, increased GA and IL-6 levels, and lower SOD concentrations than the normal cognitive function group (all P < 0.05). GA/HbA1c was negatively correlated with the MMSE (r = -0.430, P = 0.007) and MoCA (r = -0.432, P = 0.007) scores. SOD was positively correlated with the MMSE (r = 0.585, P=0.014) and MoCA (r = 0.635, P=0.006) scores. IL-6 was negatively correlated with the MoCA score (r = -0.421, P=0.015). Age and GA/HbA1c were independent factors contributing to cognitive dysfunction. The areas under the ROC curves of GA and GA/HbA1c for the diagnosis of cognitive dysfunction were 0.712 and 0.720, respectively.

Conclusions

GA and GA/HbA1c are related to cognitive dysfunction in elderly patients with T2DM.

Analysis of factors related to cognitive impairment in a community-based, complete enumeration survey in Japan: the Nakayama study

BACKGROUND

The number of patients with cognitive disorders is rapidly increasing in the world, becoming not only a medical problem, but also a social problem. There have been many reports that various factors are associated with cognitive dysfunction, but the factors have not yet been fully identified. This was a community-based complete enumeration study which aimed to identify risk and protective factors for dementia.

METHODS

The first phase included all residents aged 65 years or older in a town in Japan. They completed many examinations, such as living conditions questionnaires, physical examination, Mini-Mental State Examination, and brain magnetic resonance imaging. The participants with suspected cognitive impairment underwent additional examinations for detailed evaluation in the second phase. Statistical analysis was performed to identify risk and protective factors for dementia after all participants were diagnosed.

RESULTS

There were 927 participants in the baseline evaluation; 611 (65.9%) were healthy, 165 (17.8%) had mild cognitive impairment (MCI), and 151 (16.3%) had dementia. The age-standardised prevalence of dementia was 9.5%. Statistical analyses for amnestic MCI and Alzheimer's disease showed that risk factors for cognitive decline were diabetes mellitus, low activities of daily living, and living alone, and that protective factors were history of exercise and drinking habit.

CONCLUSION

The present findings suggest that several lifestyle-related diseases and factors are associated with cognitive decline. These results support similar findings from previous studies and will be helpful for preventing dementia in the future.

Protein glycation in diabetes mellitus

Diabetes mellitus is the ninth leading cause of mortality worldwide. It is a complex disease that manifests as chronic hyperglycemia. Glucose exposure causes biochemical changes at the proteome level as reflected in accumulation of glycated proteins. A prominent example is hemoglobin A1c (HbA1c), a glycated protein widely accepted as a diabetic indicator. Another emerging biomarker is glycated albumin which has demonstrated utility in situations where HbA1c cannot be used. Other proteins undergo glycation as well thus impacting cellular function, transport and immune response. Accordingly, these glycated counterparts may serve as predictors for diabetic complications and thus warrant further inquiry. Fortunately, modern proteomics has provided unique analytic capability to enable improved and more comprehensive exploration of glycating agents and glycated proteins. This review broadly covers topics from epidemiology of diabetes to modern analytical tools such as mass spectrometry to facilitate a better understanding of diabetes pathophysiology. This serves as an attempt to connect clinically relevant questions with findings of recent proteomic studies to suggest future avenues of diabetes research.

ZiBuPiYin recipe ameliorates diabetes-associated cognitive decline by improving neuronal mitochondrial function in chronic psychologically stressed zucker diabetic fatty rats

ETHNOPHARMACOLOGICAL RELEVANCE

Zibu Piyin Recipe (ZBPYR) is a traditional Chinese medicine compound composed of 12 kinds of Chinese herbal medicines including red ginseng and yam. Long-term basic and clinical applications have proved that ZBPYR can prevent and treat cognitive dysfunction. Previous studies showed that chronic psychological stress can increase the risk of type 2 diabetes mellitus (T2DM), and lead to cognitive decline. Mitochondrial dysfunction plays a key role in chronic psychological stress-induced diabetes mellitus. While the mechanism of mitochondrial dysfunction and insulin resistance in diabetes-associated cognitive decline (DACD) is unclear.

AIM OF THE STUDY

Our previous research found that a ZiBuPiYin recipe (ZBPYR) has significant pharmacological effects against DACD. The present study investigated changes in mitochondrial dysfunction in the brain and the mechanism of insulin resistance and mitochondrial damage to explore the relationship between neuronal mitochondrial dysfunction and insulin resistance in chronic psychologically stressed DACD rats.

MATERIALS AND METHODS

Zucker diabetic fatty (ZDF) rats with spontaneous T2DM and rats with diabetic cognitive impairment that was induced by chronic psychological stress were used in in vivo experiments. PC12 cells that were damaged by rotenone were used for the in vitro experiment.

RESULTS

The findings indicated that the number of mitochondria decreased, morphology and membrane potential were damaged, and reactive oxygen species increased in the cortex and hippocampus in psychologically stressed DACD rats. Protein kinase Cβ2 (PKCβ2) activation and insulin resistance were markedly induced by chronic psychological stress, together with decreases in peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α) and mitochondrial fusion protein 2 (Mfn2). Furthermore, ZBPYR exerted protective effects both in in vivo and in vitro.

CONCLUSION

Mitochondrial damage and insulin resistance were observed in the brain in chronic psychologically stressed DACD rats. The ZBPYR significantly improved brain mitochondrial damage and insulin resistance in chronic psychologically stressed DACD rats. These results provide novel insights for the development of ZBPYR as a traditional Chinese medicine for the treatment of chronic psychological stress and DACD.

Inverse correlation of free triiodothyronine with glycated albumin and the glycated albumin/glycated hemoglobin ratio in hemodialysis patients: a cross-sectional study

Background

That the prevalence of low triiodothyronine (T3) syndrome is high among hemodialysis (HD) patients has been previously established. Herein, we examined the association of glycated albumin (GA) and the GA to glycated hemoglobin (HbA1c) ratio (GA/HbA1c) with free triiodothyronine (FT3) in HD patients.

Methods

We conducted a cross-sectional study on 134 patients (68 patients with diabetes mellitus [DM group] and 66 patients without diabetes mellitus [non-DM group]) who received maintenance HD at our dialysis clinic between 2014 and 2018. Univariate linear regression analyses of GA, GA/HbA1c, or HbA1c with several clinical variables were primarily conducted. Multiple regression analyses with GA (or GA/HbA1c) as the objective variable were conducted with explanatory variable FT3 adjusted for age, sex, Hb, Alb, and average plasma glucose (Av-PG) (or HbA1c).

Results

In the DM and non-DM groups, GA tended to be inversely correlated with FT3, although significantly so only in the non-DM group. GA/HbA1c also showed a strong significant inverse correlation with FT3 in the DM group and the non-DM group. FT3 and GA/HbA1c were also significantly correlated with the Geriatric Nutritional Risk Index in the DM group and non-DM group. In the multivariate analysis, which was adjusted for age, sex, Hb, Alb, and HbA1c, FT3 was a significant and independent factor associated with GA in the DM group (β = − 0.334, p < 0.001) and in the non-DM group (β = − 0.412, p < 0.001). The regression equations obtained by stepwise multiple regression analyses using all of these variables as independent variables were GA = 3.3HbA1c − 4.4FT3 + 1.9sex + 8.8 for the DM group and GA =  − 2.4FT3 + 0.04Age − 0.5Hb + 25.2 for the non-DM group. These contribution rates (i.e., coefficient of determination) were R2 = 0.708 in the DM group and R2 = 0.347 in the non-DM group, In the DM group, the estimation formulas, based on the regression equation [GA (men) = 3.3HbA1c − 4.4FT3 + 10.7 and GA (women) = 3.3HbA1c − 4.4FT3 + 8.8], showed very high contribution rates (i.e., coefficient of determination R2 = 0.674 for men and 0.761 for women) for the GA measured values.

Conclusions

GA and GA/HbA1c have a close relationship with FT3 in HD patients. The estimation formulas of GA could be obtained. In particular, the estimation formulas in the DM group are believed to be useful in considering HbA1c and FT3 simultaneously when evaluating GA.

Behavioral and Proteomic Studies Reveal Methylglyoxal Activate Pathways Associated with Alzheimer's Disease

Diabetes is one of the major risk factors for Alzheimer's disease (AD) development. The role of elevated levels of glucose, methylglyoxal (MGO), and advanced glycation end products (AGEs) in the pathogenesis of AD is not well understood. In this pursuit, we studied the role of methylglyoxal in the pathogenesis of AD in rat models. The elevated plus-maze (EPM) behavioral study indicated that MGO induces anxiety. Treatment of telmisartan (RAGE expression inhibitor) and aminoguanidine (MGO quencher) attenuated MGO induced anxiety. Further, hippocampal proteomics demonstrated that MGO treated rats differentially regulate proteins involved in calcium homeostasis, mitochondrial functioning, and apoptosis, which may affect neurotransmission and neuronal plasticity. The hippocampal tau phosphorylation level was increased in MGO treated rats, which was reduced in the presence of aminoguanidine and telmisartan. The plasma fructosamine level was increased upon MGO treatment. Hippocampal histochemistry showed vascular degeneration and neuronal loss upon MGO treatment. This study provides mechanistic insight into the role of MGO in the diabetes-associated development of AD.

GA/HbA1c ratio is a simple and practical indicator to evaluate the risk of metabolic dysfunction-associated fatty liver disease in type 2 diabetes: an observational study

BACKGROUND

It is still debatable whether glycated albumin/glycated hemoglobin A1C (GA/HbA1C) ratio is associated with metabolic dysfunction-associated fatty liver disease (MAFLD), and few studies have been conducted in type 2 diabetes mellitus (T2DM). Therefore, we aimed to investigate the association between GA/HbA1C ratio and MAFLD and to evaluate whether GA/HbA1C ratio can be used an indicator of MAFLD in Chinese patients with T2DM.

METHODS

This cross-sectional study consisted of 7117 T2DM patients including 3296 men and 3821 women from real-world settings. Abdominal ultrasonography was performed to diagnose MAFLD. In addition to comparing the clinical characteristics among the GA/HbA1C ratio quartile groups, we also investigated the associations of GA/HbA1C ratio and quartiles with MAFLD in T2DM subjects.

RESULTS

There was a significantly decreased trend in the MAFLD prevalence across the GA/HbA1C ratio quartiles (56.3%, 47.4%, 37.8%, and 35.6% for the first, second, third, and fourth quartile, respectively, P < 0.001 for trend) after adjusting for gender, age, and diabetes duration. Fully adjusted Binary logistic regression indicated that both GA/HbA1C ratio (OR: 0.575, 95% CI: 0.471 to 0.702, P < 0.001) and quartiles (P < 0.001 for trend) were inversely associated with the presence of MAFLD among T2DM patients. Additionally, HOMA2-IR values were clearly increased in the T2DM subjects with MAFLD compared with those without MAFLD (P < 0.001), and markedly increased from the highest to the lowest GA/HbA1C ratio quartile (P < 0.001 for trend).

CONCLUSIONS

GA/HbA1C ratio is closely and negatively associated with MAFLD in T2DM subjects, which may attribute to that GA/HbA1C ratio reflects the degree of insulin resistance. GA/HbA1C ratio may act as a simple and practical indicator to evaluate the risk of MAFLD in T2DM.

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.

Individual and Combined Associations of Glucose Metabolic Components With Cognitive Function Modified by Obesity

Aim

We aimed to detect the individual and combined effect of glucose metabolic components on cognitive function in particular domains among older adults.

Methods

Data of 2,925 adults aged over 60 years from the 2011 to 2014 National Health and Nutrition Examination Survey were analyzed. Individuals' cognitive function was evaluated using the Digit Symbol Substitution Test (DSST), the Animal Fluency Test (AF), the Consortium to Establish a Registry for Alzheimer's Disease Immediate Recall (CERAD-IR), and CERAD Delayed Recall (CERAD-DR). Participants' glucose metabolic health status was determined based on fasting plasma glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR), glycated hemoglobin (HbA1c), and 2-h postload glucose. Linear regression models were used to delineate the associations of cognitive function with individual glucose metabolic component and with metformin use. Logistic regression models were performed to evaluate the associations of cognition with the number of glucose metabolic risk components.

Results

CERAD-IR was significantly associated with HOMA-IR and insulin. HbA1c was related to all the cognitive tests except AF. Among participants without obesity, HOMA-IR and insulin were both negatively associated with CERAD-IR and CERAD-DR. Odds of scoring low in DSST increased with the number of glucose metabolic risk components (odds ratio 1.94, 95% confidence interval [CI] 1.26 to 2.98). Metformin use was associated with better performance in DSST among diabetes patients (β = 4.184, 95% CI 1.655 to 6.713).

Conclusions

Our findings support the associations of insulin resistance and glycemic level with cognitive function in key domains, especially among adults without obesity. There is a positive association between metformin use and cognition.

Diabetes Mellitus, Elevated Hemoglobin A1c, and Glycated Albumin Are Associated with the Presence of All-Cause Dementia and Alzheimer's Disease: The JPSC-AD Study

BACKGROUND

Glucose dysmetabolism is an important risk factor for dementia.

OBJECTIVE

We investigated the associations of diabetes mellitus, the levels of glycemic measures, and insulin resistance and secretion measures with dementia and its subtypes in a cross-sectional study.

METHODS

In this study, 10,214 community-dwelling participants were enrolled. Hemoglobin A1c (HbA1c), the homeostasis model assessment (HOMA) for insulin resistance (HOMA-IR), the HOMA of percent β-cell function (HOMA-β), and the glycated albumin (GA) was evaluated. The associations of each measure with Alzheimer's disease (AD) and vascular dementia (VaD) were investigated.

RESULTS

The multivariable-adjusted odds ratios (ORs) of AD were significantly higher in participants with diabetes mellitus than in those without diabetes (1.46 [95% CI: 1.08-1.97]). Higher HbA1c levels were significantly associated with AD at diabetes (≥6.5%) and even at prediabetes (5.7 %-6.4 %) levels; multivariable-adjusted ORs for AD in participants at the diabetes level were 1.72 (95% CI: 1.19-2.49), and those in participants at the prediabetes level were 1.30 (95% CI: 1.00-1.68), compared with those in normal participants. Moreover, higher GA levels were associated with AD. No associations were observed between the diabetic status or the levels of glycemic measures and VaD. In addition, no significant relationships were observed between insulin resistance and secretion measurements and AD and VaD.

CONCLUSION

Our findings indicate that diabetes mellitus and hyperglycemia are significantly associated with AD, even in individuals at the prediabetes level.

Glycated albumin as biomarker: Evidence and its outcomes

Glycemic control markers are important for the diagnosis and treatment of diabetes. Hemoglobin A1c (A1C) is an important marker that is mandatory in routine medical examinations; however, it is well known that it has some limitations. In this review, we focus on the limitation of A1C and introduce a relatively new marker, glycated albumin (GA), which can be used to complement A1C. First, for a better understanding of the characteristics of each marker, we sort the similarities and differences of glycemic control markers as well as the characteristics of each marker. Second, we point out the limitation of A1C, introduce GA as an alternative indicator, and discuss the limitations of GA. Finally, we summarize important evidence regarding the utility of GA. We hope that this review provides useful information that permits more effective usage of GA as well as other glycemic control markers.

Glycemic Control, Diabetic Complications, and Risk of Dementia in Patients With Diabetes: Results From a Large U.K. Cohort Study

OBJECTIVE

Type 2 diabetes is an established risk factor for dementia. However, the roles of glycemic control and diabetic complications in the development of dementia have been less well substantiated. This large-scale cohort study aims to examine associations of longitudinal HbA_1c levels and diabetic complications with the risk of dementia incidence among patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

Data of eligible patients with diabetes, aged ≥50 years in the U.K. Clinical Practice Research Datalink from 1987 to 2018, were analyzed. Time-varying Cox regressions were used to estimate adjusted hazard ratios (HRs) and 95% CIs for dementia risk.

RESULTS

Among 457,902 patients with diabetes, 28,627 (6.3%) incident dementia cases were observed during a median of 6 years' follow-up. Patients with recorded hypoglycemic events or microvascular complications were at higher risk of dementia incidence compared with those without such complications (HR 1.30 [95% CI 1.22-1.39] and 1.10 [1.06-1.14], respectively). The HbA_1c level, modeled as a time-varying exposure, was associated with increased dementia risk (HR 1.08 [95% CI 1.07-1.09] per 1% HbA_1c increment) among 372,287 patients with diabetes with postdiagnosis HbA_1c records. Similarly, a higher coefficient of variation of HbA_1c during the initial 3 years of follow-up was associated with higher subsequent dementia risk (HR 1.03 [95% CI 1.01-1.04] per 1-SD increment).

CONCLUSIONS

Higher or unstable HbA_1c levels and the presence of diabetic complications in patients with type 2 diabetes are associated with increased dementia risk. Effective management of glycemia might have a significant role in maintaining cognitive health among older adults with diabetes.

Diabetic Theory in Anti-Alzheimer's Drug Research and Development. Part 2: Therapeutic Potential of cAMP-Specific Phosphodiesterase Inhibitors

Alzheimer's disease (AD) is one of the most prevalent age-related neurodegenerative disease that affects the cognition, behavior, and daily activities of individuals. Studies indicate that this disease is characterized by several pathological mechanisms, including the accumulation of amyloid-beta peptide, hyperphosphorylation of tau protein, impairment of cholinergic neurotransmission, and increase in inflammatory responses within the central nervous system. Chronic neuroinflammation associated with AD is closely related to disturbances in metabolic processes, including insulin release and glucose metabolism. As AD is also called type III diabetes, diverse compounds having antidiabetic effects have been investigated as potential drugs for its symptomatic and disease-modifying treatment. In addition to insulin and oral antidiabetic drugs, scientific attention has been paid to cyclic-3',5'-adenosine monophosphate (cAMP)-specific phosphodiesterase (PDE) inhibitors that can modulate the concentration of glucose and related hormones and exert beneficial effects on memory, mood, and emotional processing. In this review, we present the most recent reports focusing on the involvement of cAMP-specific PDE4, PDE7, and PDE8 in glycemic and inflammatory response controls as well as the potential utility of the PDE inhibitors in the treatment of AD. Besides the results of in vitro and in vivo studies, the review also presents recent reports from clinical trials.

Are diabetes-related factors associated with the social roles of elderly patients with diabetes?

AIMS

To identify factors associated with social roles, including glycemic parameters, diabetic complications, and diabetes treatment, in elderly patients with diabetes.

METHODS

We included diabetic patients aged ≥65 years undergoing outpatient treatment at Ise Red Cross Hospital. Functional capacity was assessed using the social role subscale, included in the Tokyo Metropolitan Institute of Gerontology Index of Competence (TMIG-IC). Multiple regression analyses were performed using social roles as dependent variables and age, body mass index, HbA1c, glycoalbumin/HbA1c, hypertension, dyslipidemia, diabetic microangiopathy, cardiovascular disease, depression, sleep disturbance, living alone, frailty, diabetic drug as explanatory variables.

RESULTS

In total, 367 patients (208 males and 159 females) were included. In men, diabetic nephropathy (coefficient, -0.496; 95% confidence interval (CI), -0.900 to -0.091; P = 0.017), depression (coefficient, -0.497; 95% CI, -0.942 to -0.051; P = 0.029), and frailty (coefficient, -0.595; 95% CI, -1.048 to -0.142; P = 0.010) were associated with a decline in social roles. In women, frailty (coefficient, -0.826; 95% CI, -1.306 to -0.346; P = 0.001) was associated with a decline in social roles.

CONCLUSIONS

Social roles may decline in elderly male diabetic patients with nephropathy, depression, and frailty and in elderly female diabetic patients with frailty.

Factors associated with social isolation and being homebound among older patients with diabetes: a cross-sectional study

OBJECTIVE

We aimed at investigating factors associated with social isolation and being homebound in older patients with diabetes.

DESIGN

Cross-sectional study.

SETTINGS

Those undergoing outpatient treatments at Ise Red Cross Hospital, Mie Prefecture.

PARTICIPANTS

Patients with diabetes aged ≥65 years.

PRIMARY AND SECONDARY OUTCOME MEASURES

Social isolation was defined as indulging in less than one interaction per week with individuals other than cohabiting family members. We defined homebound as going outside home less than once a day. To identify factors associated with social isolation and being homebound, we performed logistic regression analysis. The dependent variable was social isolation or homebound and independent variables were basic attributes, glycaemic parameters, complications and treatment details.

RESULTS

We analysed 558 cases (320 men and 238 women). Among these, 174 (31.2%) were socially isolated; meanwhile, 87 (15.6%) were homebound. The glycoalbumin/haemoglobin A1c ratio (OR 4.52; 95% CI 1.07 to 19.1; p=0.040) and the Tokyo Metropolitan Institute of Gerontology Index of Competence (TMIG-IC) scores (OR 0.72; 95% CI 0.57 to 0.90; p=0.006) had significant associations with social isolation. TMIG-IC scores (OR 0.78; 95% CI 0.66 to 0.92; p=0.003) and insulin use (OR 4.29; 95% CI 1.14 to 16.1; p=0.031) were associated with being homebound.

CONCLUSION

In older patients with diabetes, glycaemic fluctuations and insulin use are associated with social isolation and being homebound, respectively. In addition, a decline in higher level functional capacity is a common factor associated with social isolation and being homebound. Thus, it is important to pay attention to social isolation and being homebound when a decline in higher level functional capacity, increased glycaemic fluctuations and insulin use in older patients with diabetes are observed.

Review of methods for detecting glycemic disorders

Prediabetes (intermediate hyperglycemia) consists of two abnormalities, impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) detected by a standardized 75-gram oral glucose tolerance test (OGTT). Individuals with isolated IGT or combined IFG and IGT have increased risk for developing type 2 diabetes (T2D) and cardiovascular disease (CVD). Diagnosing prediabetes early and accurately is critical in order to refer high-risk individuals for intensive lifestyle modification. However, there is currently no international consensus for diagnosing prediabetes with HbA1c or glucose measurements based upon American Diabetes Association (ADA) and the World Health Organization (WHO) criteria that identify different populations at risk for progressing to diabetes. Various caveats affecting the accuracy of interpreting the HbA1c including genetics complicate this further. This review describes established methods for detecting glucose disorders based upon glucose and HbA1c parameters as well as novel approaches including the 1-hour plasma glucose (1-h PG), glucose challenge test (GCT), shape of the glucose curve, genetics, continuous glucose monitoring (CGM), measures of insulin secretion and sensitivity, metabolomics, and ancillary tools such as fructosamine, glycated albumin (GA), 1,5- anhydroglucitol (1,5-AG). Of the approaches considered, the 1-h PG has considerable potential as a biomarker for detecting glucose disorders if confirmed by additional data including health economic analysis. Whether the 1-h OGTT is superior to genetics and omics in providing greater precision for individualized treatment requires further investigation. These methods will need to demonstrate substantially superiority to simpler tools for detecting glucose disorders to justify their cost and complexity.

Elevated serum glycated albumin and glycated albumin : hemoglobin A1c ratio were associated with hippocampal atrophy in a general elderly population of Japanese: The Hisayama Study

AIMS/INTRODUCTION

To investigate the association of alternative glycemic measures - namely, serum glycated albumin (GA), hemoglobin A1c (HbA1c ) and the GA : HbA1c ratio - with global brain and hippocampal atrophy in a general elderly Japanese population.

MATERIALS AND METHODS

A total of 1,278 Japanese individuals aged ≥65 years in a community participated in brain magnetic resonance imaging scanning and screening examination of health status in 2012. We measured total brain volume (TBV), hippocampal volume (HV) and intracranial volume (ICV) using the data from the magnetic resonance imaging examination. The association of each glycemic measure with the ratios of TBV : ICV (an indicator of global brain atrophy) and HV : ICV (an indicator of hippocampal atrophy) was examined by analysis of covariance.

RESULTS

The mean values of the TBV : ICV and HV : ICV ratios decreased significantly with elevating serum GA levels and GA : HbA1c ratio levels (all P for trend < 0.05), but not with higher HbA1c levels, after adjusting for age, sex, low education, systolic blood pressure, antihypertensive medication, diabetes mellitus, serum total cholesterol, electrocardiogram abnormalities, body mass index, smoking habits, alcohol drinking habits and regular exercise. These significant associations were still observed in the sensitivity analysis after excluding individuals with mild cognitive impairment and dementia. In addition, increased serum GA levels and the GA : HbA1c ratio levels, but not HbA1c , were closely associated with lower mean values of the TBV : ICV and HV : ICV ratios, irrespective of the presence or absence of diabetes mellitus.

CONCLUSIONS

The present study suggests that higher serum GA and higher GA : HbA1c ratio are significantly associated with global brain and hippocampal atrophy.

Antidiabetic Drugs for the Risk of Alzheimer Disease in Patients With Type 2 DM Using FAERS

Alzheimer disease (AD) may develop after the onset of type 2 diabetes mellitus (T2DM), and the risk of AD may depend on the antidiabetic drug administered. We compared the risk of AD among 66 085 patients (≥ 65 years) with T2DM (1250 having concomitant AD) who had been administered antidiabetic drug monotherapy for T2DM who had voluntarily reported themselves in the Food and Drug Administration Adverse Event Reporting System. The risk of AD from the use of different antidiabetic drug monotherapies compared to that of metformin monotherapy was assessed by logistic regression. Rosiglitazone (adjusted reporting odds ratio [aROR] = 0.11; 95% confidence interval [CI]: 0.07-0.17; P < .001), exenatide (aROR = 0.22; 95% CI: 0.11-0.37; P < .001), liraglutide (aROR = 0.36; 95% CI: 0.19-0.62; P < .001), dulaglutide (aROR = 0.39; 95% CI: 0.17-0.77; P = .014), and sitagliptin (aROR = 0.75; 95% CI: 0.60-0.93; P = .011) were found to have a significantly lower associated risk of AD than that of metformin. Therefore, the administration of glucagon-like peptide 1 receptor agonists and rosiglitazone may reduce the risk of AD in patients with T2DM.

The Association of Late-Life Diabetes Status and Hyperglycemia With Incident Mild Cognitive Impairment and Dementia: The ARIC Study

OBJECTIVE

We sought to examine associations in older adults among diabetes, glycemic control, diabetes duration, and biomarkers of hyperglycemia with incident mild cognitive impairment (MCI) and incident dementia.

RESEARCH DESIGN AND METHODS

We conducted a prospective analysis of 5,099 participants from the Atherosclerosis Risk in Communities (ARIC) Study who attended the fifth (2011-2013) exam. Cognitive status was assessed during follow-up via telephone calls, death certificate codes, surveillance, and a follow-up examination (2016-2017). We defined incident cognitive impairment as incident MCI or incident dementia in persons dementia-free at the index examination; we also examined each outcome separately. Diabetes was defined using self-report, medications, or HbA1c ≥6.5%; poor glycemic control in persons with diabetes was defined as HbA1c ≥7%. We examined the following biomarkers of hyperglycemia: HbA1c, fructosamine, glycated albumin, and 1,5-anhydroglucitol.

RESULTS

Mean age at baseline was 76 years, 59% were female, and 21% were black. Diabetes (hazard ratio [HR] 1.14 [95% CI 1.00, 1.31]), poor glycemic control in persons with diabetes (HR 1.31 [95% CI 1.05, 1.63]), and longer diabetes duration (≥5 vs. <5 years; HR 1.59 [95% CI 1.23, 2.07]) were significantly associated with incident cognitive impairment. We found a J-shaped association between HbA1c and incident dementia. Glycated albumin and fructosamine were also associated with incident dementia, independently of HbA1c. HbA1c and fructosamine were also associated with incident MCI.

CONCLUSIONS

Diabetes status, poor glycemic control, and longer diabetes duration were associated with worse cognitive outcomes over a median follow-up of 5 years.

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.

Reduction in glucose fluctuations in elderly patients with type 2 diabetes using repaglinide: A randomized controlled trial of repaglinide vs sulfonylurea

AIMS/INTRODUCTION

Glinides are antidiabetic drugs that enhance the early phase of insulin secretion, but have been considered to be less effective at lowering blood glucose than sulfonylureas. However, glinides show a lower risk of hypoglycemia and a greater effect on postprandial hyperglycemia, and are particularly recommended for use in elderly patients with type 2 diabetes. We investigated the efficacy and safety of repaglinide compared with sulfonylurea for the treatment of elderly patients.

MATERIALS AND METHODS

In the present multicenter, prospective, randomized, open-label, controlled trial, 57 elderly lean patients with type 2 diabetes who were being treated with sulfonylureas were studied. They were either switched to repaglinide (Repa group) or continued a sulfonylurea (SU group) for 12 weeks. The primary outcome comprised the change in glycemic control, and among the secondary outcomes was the presence of hypoglycemia and drug compliance.

RESULTS

Although glycated hemoglobin (HbA1c) was not significantly different between the two groups (SU +0.02% vs Repa -0.07%), greater improvements in the glycated albumin (GA) and GA to HbA1c ratio (GA/HbA1c) were observed in the Repa group (ΔGA, SU +0.12% vs Repa -1.15%; ΔGA/HbA1c, SU +0.01 vs Repa -0.13; each P < 0.01) without increasing hypoglycemia. When the Repa group was subdivided according to whether GA improved, the SU dose before switching to repaglinide was significantly smaller and the homeostatic model assessment of β-cell function was significantly higher in the GA improvement subgroup.

CONCLUSIONS

Switching from SU to Repa improved GA and GA/HbA1c, and had favorable effects on glucose fluctuation in elderly patients with type 2 diabetes.

Identification of Protein Kinase C Isoforms Involved in Type 1 Diabetic Encephalopathy in Mice

Diabetic encephalopathy is a complication of diabetes mellitus characterized by impaired cognitive functions. Protein kinase C (PKC) isoforms are rarely reported on diabetic encephalopathy, although they have been believed to play crucial roles in other diabetic complications. In this study, streptozotocin- (STZ-) induced diabetic mice were found to exhibit learning and memory deficits in the Morris water maze test. Meanwhile, the expression of cPKCβII, nPKCε, and cPKCγ did not change in the hippocampus, cortex, and striatum at 2 and 8 weeks after STZ injection. The nPKCε translocation to the membrane, where it is activated, was not altered in the above brain regions at 2 and 8 weeks after STZ injection. Nevertheless, cPKCβII translocation to the membrane was significantly decreased in the cortex and hippocampus at 8 weeks after STZ injection. The translocation of cPKCγ from the cytosol to the membrane was remarkably decreased in the hippocampus at 2 and 8 weeks and in the cortex and striatum at 8 weeks after STZ injection. In addition, deletion of cPKCγ aggravated the impairment of spatial learning and memory. In conclusion, our results suggest that the decrease in the activity of cPKCβII and cPKCγ, especially cPKCγ, may play key roles in the pathogenesis of diabetic encephalopathy.