Association of hsCRP and vitamin D levels with mild cognitive impairment in elderly type 2 diabetic patients

Association of vitamin D and cognition in people with type 2 diabetes: a systematic review

CONTEXT

There is a high prevalence of vitamin D deficiency and impaired cognitive function in people with type 2 diabetes mellitus (T2DM).

OBJECTIVE

To critically and systematically review the literature on the association between vitamin D status and cognitive performance in people with type 2 diabetes.

DATA SOURCES

This review was conducted according to PRISMA recommendations. MEDLINE, SCOPUS, the Cochrane Library, and Web of Science databases were searched using the terms "Diabetes Mellitus, Type 2", "Cognitive Function", and "Vitamin D".

DATA EXTRACTION

Eight observational and 1 randomized study were included, containing data of 14 648 adult and elderly individuals (19-74 y). All extracted data were compiled, compared, and critically analyzed.

DATA ANALYSIS

There is no strong evidence that lower serum concentrations of vitamin D and vitamin D-binding protein are associated with worsening cognitive function in individuals with T2DM. Vitamin D supplementation (12 wk) improved the scores of some executive functioning tests, although there was no difference between low doses (5000 IU/wk) and high doses (50 000 IU/wk).

CONCLUSIONS

There is no high-quality evidence demonstrating an association between vitamin D status and cognitive function, or clinical benefits on cognition from vitamin D supplementation in individuals with T2DM. Future studies are needed. Systematic Review Registration: PROSPERO registration no. CRD42021261520.

Correlation between inflammatory biomarkers, cognitive function and glycemic and lipid profiles in patients with type 2 diabetes mellitus: A systematic review and meta-analysis

This study aimed to quantitatively estimate the correlation between systemic inflammation with cognitive function, as well as glycemic and lipid profiles in patients with type 2 diabetes mellitus (T2DM). The PubMed, Web of Science, EMBASE, SCOPUS, CNKI, Wanfang, VIP, and CBM databases were searched from its inception until June 2023 (PROSPERO registration: CRD42022356889). We analyzed data extracted from observational studies to quantify the correlations (r) as the pooled effect size and further performed subgroup analyses and sensitivity analyses. A total of 32 studies involving 7,483 patients with T2DM were included. The findings revealed a significant moderate negative correlation between interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and C-reactive protein (CRP) levels with Montreal Cognitive Assessment scores. TNF-α levels also had moderate negative correlation with Mini-Mental State Examination scores. For glycemic and lipid profiles, there was a significant moderate positive correlation between CRP and TNF-α levels and glycated hemoglobin (HbA1c), and TNF-α levels were also found to be lowly positively correlated with fasting blood glucose (FBG). CRP levels were found to have a low positive correlation with total cholesterol (TC), and IL-6 levels were found to be lowly positively correlated with triglycerides. The results indicate that elevated levels of IL-6, CRP, and TNF-α are significantly associated with cognitive impairment in patients with T2DM and may serve as inflammatory markers for T2DM with mild cognitive impairment. The CRP and TNF-α levels were more strongly correlated with HbA1c than with FBG and TC. Further research is needed to determine the clinical value of these inflammatory biomarkers and to investigate potential causal mechanisms underlying this association.

Inflammatory markers in type 2 diabetes with vs. without cognitive impairment; a systematic review and meta-analysis

People with type 2 diabetes mellitus (T2DM) are at increased risk of mild cognitive impairment and dementia. Systemic inflammation has been proposed as a common risk factor. This study aimed to summarize the clinical data pertaining to peripheral blood inflammatory markers. We identified original peer-reviewed articles reporting blood inflammatory marker concentrations in groups of people with a T2DM diagnosis who have cognitive impairment (CI; including mild cognitive impairment, Alzheimer's disease, vascular cognitive impairment) vs. normal cognition (NC). Between-group standardized mean differences (SMD) were summarized in random effects meta-analyses. From 2108 records, data were combined quantitatively from 40 studies. Concentrations of interleukin-6 (IL-6; N_CI/N_NC = 934/3154, SMD 0.74 95% confidence interval [0.07, 1.42], Z₅ = 2.15, p = 0.03; I² = 98.08%), C-reactive protein (CRP; N_CI/N_NC = 1610/4363, SMD 0.80 [0.50, 1.11], Z₁₄ = 5.25, p < 0.01; I² = 94.59%), soluble vascular cell adhesion molecule-1 (sVCAM-1; N_CI/N_NC = 104/1063, SMD 1.64 95% confidence interval [0.21, 3.07], Z₂ = 2.25, p = 0.02; I² = 95.19%), and advanced glycation end products (AGEs; N_CI/N_NC = 227/317, SMD 0.84 95% confidence interval [0.41, 1.27], Z₂ = 3.82, p < 0.01; I² = 81.07%) were higher among CI groups compared to NC. Brain derived neurotropic factor (BDNF) concentrations were significantly lower in CI compared to NC (N_CI/N_NC = 848/2063, SMD -0.67 95% confidence interval [-0.99, -0.35], Z₃ = -4.09, p < 0.01; I² = 89.20%). Cognitive impairment among people with T2DM was associated with systemic inflammation and lower BDNF concentrations. These inflammatory characteristics support an increased inflammatory-vascular interaction associated with cognitive impairment in T2DM. PROSPERO (CRD42020188625).

Plasma Nesfatin-1: Potential Predictor and Diagnostic Biomarker for Cognitive Dysfunction in T2DM Patient

PURPOSE

Nesfatin-1 plays a crucial role in glucose metabolism and cognitive function. This study aimed to investigate the correlation between plasma nesfatin-1 levels and clinical indicators and cognitive function in patients with type 2 diabetes mellitus (T2DM).

METHODS

Demographic and medical history data, physical examination, and biochemical test results of 132 T2DM patients were collected. The plasma concentrations of nesfatin-1, C-reactive protein (CRP), interleukin-6 (IL-6), soluble triggering receptors expressed on myeloid cells 1 (sTREM1), and sTREM2 in T2DM patients were measured. Cognitive function was evaluated using the Behavior Rating Inventory of Executive Function-Adult (BRIEF-A). The patients were divided into two groups: a low-nesfatin-1 group (n = 75) and a high-nesfatin-1 group (n = 57) based on a plasma nesfatin-1 concentration less than or above the 50th percentile value of all the samples.

RESULTS

The results showed that plasma HbA1c levels were positively correlated with CRP, IL-6, sTREM1, and sTREM2 levels in patients with T2DM (P < 0.05). Plasma nesfatin-1 concentrations were positively associated with diabetes-related biochemical indicators including glycated haemoglobin (HbA1c), insulin, and homeostatic model assessment of insulin resistance (HOMA-IR), and inflammation-related indicators including CRP, IL-6, sTREM1, and sTREM2 among patients with T2DM (P < 0.05). Moreover, T2DM patients with high nesfatin-1 levels showed higher HbA1c and fasting plasma glucose (FPG) levels (P < 0.05). Furthermore, T2DM patients with high nesfatin-1 levels also showed higher BRIEF-A scores (P = 0.01). Additionally, T2DM patients with high total scores of BRIEF-A (scores > 50th percentile) could be identified with a sensitivity of 59.1% and a specificity of 72.7% by nesfatin-1.

CONCLUSION

These findings indicate that plasma nesfatin-1 might be involved in the T2DM-associated comorbidities and the development of cognitive dysfunction, and the mechanism underlying this involvement is related to the imbalance in the expression of CRP, IL-6, sTREM1, and sTREM2 levels.

Association of Serum Melatonin Level with Mild Cognitive Impairment in Type 2 Diabetic Patients: A Cross-Sectional Study

OBJECTIVES

Melatonin is an essential neuroendocrine hormone that participates in the regulation of sleep rhythm and cognitive function. This study aimed to determine serum melatonin levels with mild cognitive impairment (MCI) in patients with type 2 diabetes (T2DM).

METHODS

A total of 247 T2DM patients were recruited in this retrospective study and divided into 75 subjects with MCI and 172 with normal cognition. Cognitive function was evaluated by the Montreal Cognitive Assessment (MoCA). Their blood sample was examined for the level of melatonin and other biochemical parameters.

RESULTS

Melatonin concentration was decreased in MCI patients to non-MCI patients (P < 0.001). Melatonin level was negatively correlated with age (r = -0.202; P = 0.001), diabetes duration (r = -0.282; P < 0.001), serum HbA1c (r = -0.195; P = 0.002), hs-CRP (r = -0.324; P < 0.001), and TSH (r = -0.184; P = 0.004) levels and positively correlated with MoCA score, serum HDL-C (r = 0.145; P < 0.001), FT3 (r = 0.241; P < 0.001), and FT4 (r = 0.169; P = 0.008) levels. The multivariable analysis indicated that fewer years of formal education, longer diabetes duration, higher serum HbA1c, higher serum hs-CRP, and lower serum melatonin are the predisposing factors for MCI.

CONCLUSION

Lower melatonin level was associated with cognitive impairment in patients with T2DM. Melatonin might serve as a potential protective molecule against cognitive dysfunction in T2DM.

Early Biomarkers of Neurodegenerative and Neurovascular Disorders in Diabetes

Diabetes mellitus (DM) is a common disease worldwide. There is a strong association between DM and neurovascular and neurodegenerative disorders. The first group mainly consists of diabetic retinopathy, diabetic neuropathy and stroke, whereas, the second group includes Alzheimer's disease, Parkinson's disease, mild cognitive impairment and dementia. The aforementioned diseases have a common pathophysiological background including insulin resistance, oxidative stress, atherosclerosis and vascular injury. The increasing prevalence of neurovascular and neurodegenerative disorders among diabetic patients has resulted in an urgent need to develop biomarkers for their prediction and/or early detection. The aim of this review is to present the potential application of the most promising biomarkers of diabetes-related neurodegenerative and neurovascular disorders, including amylin, β-amyloid, C-reactive protein (CRP), dopamine, gamma-glutamyl transferase (GGT), glycogen synthase kinase 3β, homocysteine, microRNAs (mi-RNAs), paraoxonase 1, phosphoinositide 3-kinases, tau protein and various growth factors. The most clinically promising biomarkers of neurovascular and neurodegenerative complications in DM are hsCRP, GGT, homocysteine and miRNAs. However, all biomarkers discussed in this review could become a part of the potential multi-biomarker screening panel for diabetic patients at risk of neurovascular and neurodegenerative complications.