Vascular endothelial growth factor during hypoglycemia in patients with type 1 diabetes mellitus: relation to cognitive function and renin-angiotensin system activity

Association of cognition with leptin and vascular endothelial growth factor in individuals with type 2 diabetes mellitus

OBJECTIVE

The 10-year intensive lifestyle intervention (ILI) of the Look AHEAD study left a legacy of relative deficits in cognitive function among participants who entered the clinical trial with obesity or a history of cardiovascular disease. We hypothesized that altered levels of two weight-sensitive proangiogenic cytokines, leptin and vascular endothelial growth factor (VEGF), accounted for this concerning finding.

METHODS

Serum leptin and VEGF concentrations were determined in 1,279 Look AHEAD participants at baseline, proximal to cessation of the interventions (Epoch 1), and an average of 4 years later (Epoch 2). Up to four standardized assessments of attention, executive function, and memory were collected during follow-up. Mixed effects models were used to assess relative differences in leptin and VEGF concentrations between intervention groups and whether these accounted for changes in cognitive composite scores.

RESULTS

ILI and diabetes support and education differences in VEGF, but not leptin, concentrations varied depending on baseline history of cardiovascular disease and obesity, but neither leptin nor VEGF concentrations accounted for the relative decrements in cognitive function in participants assigned to ILI.

CONCLUSIONS

Alterations in two weight-sensitive proangiogenic cytokines did not account for the long-term adverse effects of ILI on cognitive function among adults with diabetes and either obesity or cardiovascular disease.

Glycemic Control is Related to Cognitive Dysfunction in Elderly People with Type 2 Diabetes Mellitus in a Rural Chinese Population

BACKGROUND

There is an increasing interest on Cognitive Impairment (CI) in patients with type 2 diabetes mellitus (T2DM), but evidence is conflicting regarding the association between CI and glycemic control.

OBJECTIVE

The present study aimed to estimate the prevalence of CI in patients with T2DM from northern rural China in order to determine whether cognitive dysfunction is related to glycemic control.

METHODS

First, we conducted a study with a cross-sectional design. We performed cluster random sampling of 1848 residents who were aged 60 years or older and lived in the countryside in China. All eligible participants with and without T2DM were interviewed and screened for cognitive function status. Diagnoses for dementia and Cognitive Impairment No Dementia (CIND) were based on the standard criteria. Second, on the basis of the results of the cross-sectional survey, we conducted a case-control study. In the T2DM group, we identified cases of T2DM with Cognitive Impairment (T2DM-CI), as well as cases of T2DM with normal cognition (T2DM-NC) to be used as controls. The effects of specific diabetes-related variables were examined. After matching for sex, age, and education level in the T2DM-CI and T2DM-NC groups, multivariate logistic regression analyses were performed to evaluate risk factors for T2DM-CI.

RESULTS

In the cross-sectional study, the prevalence of T2DM with CIND and dementia were 28.3% (95% CI: 23.5-33.2) and 9.5% (95% CI: 6.3-12.6), respectively. Compared with subjects without DM, the prevalence of CI in T2DM patients was more frequent than the prevalence of CI in the general population in almost every age group. In the case-control study, the multivariate logistic regression analyses showed that variables, including duration from diabetes onset, glycosylated hemoglobin A1c level (HbA1c), and severe hypoglycemia history, were significantly associated with an increased risk of CI in patients with T2DM (odds ratios [ORs] [95%CIs]: 1.67 [1.03-2.70], 1.40 [1.15-1.72], and 2.72 [1.02- 7.21], respectively [P <0.05]).

CONCLUSION

The present study demonstrates a high prevalence of CI in patients with T2DM among the elderly population of rural China. Glycemic control, including HbA1c and exposure to severe hypoglycemia, affected cognitive function in patients with T2DM.

The characteristic of cognitive function in Type 2 diabetes mellitus

AIM

To identify characteristics of neuropsychological function among elderly individuals with Type 2 diabetes mellitus with mild cognitive impairment (T2DM-MCI) and evaluate domain-specific effects of T2DM on cognition.

METHODS

This was a cross-sectional study conducted in Tianjin, China. MCI subjects (n=246) and controls were identified in elderly individuals with diabetes, and groups were matched in a 1:1 ratio for sex, age and educational level. Cognitive function was assessed using WAIS-III (block design, digit span), Trail Making Test A, Trail Making Test B, WMS-III (word list learning, logical memory), verbal fluency and MMSE. We used multivariable logistic regression to find diabetic factors associated with MCI.

RESULTS

The mean MMSE score was 22.73 ± 2.32 in subjects with T2DM-MCI, versus 26.71 ± 2.43 in subjects cognitive normal (P<0.001). Executive and visuospatial functions were more impaired in individuals with T2DM-MCI than in those without, as assessed using block design (P<0.001), digit span test (P<0.001), and Trails B (P<0.001). For memory, subjects with T2DM-MCI did worse than those cognitive normal on the word learning list delayed recall (P=0.015). Diabetic-related factors such as longer duration of T2DM, higher HbA1c, insulin treatment was associated with a lower level of cognitive functioning using MMSE, block design, delayed recall and Trails B test.

CONCLUSIONS

T2DM should be considered a risk factor for MCI. This risk may be associated with duration of diabetes, use of glucose-lowering medications, degree of glucose control. To decrease risk of MCI, it is important to monitor glucose control and adjust medications appropriately in elderly patients.

Effects of glycated low-density lipoprotein on cell viability, proliferation, and growth factors of mouse embryo fibroblasts

The predominant cause of death in diabetic patients is atherosclerotic coronary artery disease (CAD). Major gross cellular changes in the vascular wall of persons with CAD include endothelial injury and foam cell formation, as well as smooth muscle cell and fibroblast proliferation. This study examined the effects of glycated low density lipoprotein (glyLDL), a biochemical marker of diabetes, on cell viability, proliferation, and the expression of multiple growth factors in mouse embryo fibroblasts (MEF). The results demonstrated that exposure to ≥150 μg/mL of glyLDL for 24 h or 100 μg/mL of glyLDL for ≥48 h either significantly reduced cell viability or increased DNA fragmentation in MEF. GlyLDL treatment (25-100 μg/mL for up to 12 h) significantly increased the abundance of proliferating cell nuclear antigen (PCNA) and achieved a peak after 4 h exposure to glyLDL. Abundances of fibroblast growth factor-basic (FGF), transforming growth factor-β (TGF), and platelet-derived growth factor-A (PDGF) in MEF reached maximal levels after 2 h exposure to 50 μg/mL of glyLDL. The maximal increase of vascular endothelial growth factor (VEGF) was detected in MEF after 4 h of exposure to 50 μg/mL of glyLDL. Inhibitors for FGF (AZD4547), VEGF, or PDGF receptors (Axitinib), but not that for TGF receptor (LY364947), significantly decreased the abundance of (PCNA) in endothelial cells. The findings suggest that early exposure to a low dosage of glyLDL transiently increases the proliferation of MEF through the upregulation of FGF, VEGF, and (or) PDGF, and prolonged exposure to high concentrations of glyLDL reduced cell viability, which possibly accelerates atherogenesis under diabetic condition.

Severe hypoglycaemia and late-life cognitive ability in older people with Type 2 diabetes: the Edinburgh Type 2 Diabetes Study

OBJECTIVE

To determine the association between lifetime severe hypoglycaemia and late-life cognitive ability in older people with Type 2 diabetes.

METHODS

Cross-sectional, population-based study of 1066 men and women aged 60-75 years, with Type 2 diabetes. Frequency of severe hypoglycaemia over a person's lifetime and in the year prior to cognitive testing was assessed using a previously validated self-completion questionnaire. Results of age-sensitive neuropsychological tests were combined to derive a late-life general cognitive ability factor, 'g'. Vocabulary test scores, which are stable during ageing, were used to estimate early life (prior) cognitive ability.

RESULTS

After age- and sex- adjustment, 'g' was lower in subjects reporting at least one prior severe hypoglycaemia episode (n = 113), compared with those who did not report severe hypoglycaemia (mean 'g'-0.34 vs. 0.05, P < 0.001). Mean vocabulary test scores did not differ significantly between the two groups (30.2 vs. 31.0, P = 0.13). After adjustment for vocabulary, difference in 'g' between the groups persisted (means -0.25 vs. 0.04, P < 0.001), with the group with severe hypoglycaemia demonstrating poorer performance on tests of Verbal Fluency (34.5 vs. 37.3, P = 0.02), Digit Symbol Testing (45.9 vs. 49.9, P = 0.002), Letter-Number Sequencing (9.1 vs. 9.8, P = 0.005) and Trail Making (P < 0.001). These associations persisted after adjustment for duration of diabetes, vascular disease and other potential confounders.

CONCLUSIONS

Self-reported history of severe hypoglycaemia was associated with poorer late-life cognitive ability in people with Type 2 diabetes. Persistence of this association after adjustment for estimated prior cognitive ability suggests that the association may be attributable, at least in part, to an effect of hypoglycaemia on age-related cognitive decline.

Decreased vascular endothelial growth factor response to acute hypoglycemia in type 2 diabetic patients with hypoglycemic coma

INTRODUCTION

Plasma vascular endothelial growth factor (VEGF) was shown to increase during acute hypoglycemia and could mediate rapid adaptation of the brain. In this study we examined the neuroendocrine response in patients with type 2 diabetes mellitus (T2DM) in hypoglycemic coma or with acute neuroglycopenic symptoms.

METHODS

We prospectively studied 135 consecutive T2DM patients admitted for severe hypoglycemia during a 2-year period. We collected clinical variables and measured plasma concentrations of VEGF, epinephrine, norepinephrine, cortisol and growth hormone at admission and 30min afterwards.

RESULTS

Thirty two patients developed hypoglycemic coma and 103 did not lose consciousness. Median plasma VEGF level of coma patients was 3.1-fold lower at baseline than that of non-coma patients, and even 5.3-fold lower 30min afterwards. Plasma epinephrine concentration was significantly lower just at baseline in coma patients. On the contrary, there were no differences in concentrations of the other hormones. Multivariate logistic regression analysis showed that VEGF concentration (OR 0.68; CI 0.51-0.95) was a protective factor against the development of coma.

CONCLUSIONS

VEGF and epinephrine responses to acute hypoglycemia are reduced in T2DM patients who develop hypoglycemic coma. An increased plasma VEGF concentration appeared to be a protective factor against the development of hypoglycemic coma.

Angiogenesis and biomarkers of cardiovascular risk in adults with metabolic syndrome

OBJECTIVES

Metabolic syndrome (MetSyn) is associated with an increased risk of atherosclerosis and fatal cardiovascular events. Angiogenesis is thought to contribute to this risk as it might be involved in the progression of atherosclerotic plaques. We investigated the levels of circulating biomarkers of angiogenesis and cardiovascular risk in adults with MetSyn and assessed their association with established metabolic risk factors.

DESIGN

The Genetic Park project is a highly inclusive cross-sectional survey (about 80% of residents) conducted in three isolated populations in Southern Italy. A total of 1000 men and women (age range: 18-98 years) were included in the analysis. Anthropometric and blood pressure measurements were recorded. Metabolic and cardiovascular biomarkers included glucose, triglycerides, total cholesterol, HDL, vascular endothelial growth factor, placental growth factor (PlGF), soluble fms-like tyrosine kinase-1, high-sensitivity C-reactive protein, high-sensitivity troponin T (hs-TnT) and N-terminal pro-brain natriuretic peptide (NT-proBNP).

RESULT

Subjects with MetSyn had higher levels of PlGF and NT-proBNP after adjustment for age, smoking and body mass index. Circulating levels of PlGF, hs-TnT and NT-proBNP were directly related to the number of criteria of MetSyn, and this association interacted with gender. There was a strong correlation between ageing and cardiovascular risk.

CONCLUSIONS

The increase in circulating levels of biomarkers of angiogenesis and cardiac function in subjects with MetSyn mirrors the pathophysiological changes occurring in the cardiovascular system. Over time, these changes might accelerate the formation and progression of atherosclerotic plaques and contribute significantly to cardiovascular morbidity and mortality risk.

Erythropoietin and vascular endothelial growth factor as risk markers for severe hypoglycaemia in type 1 diabetes

OBJECTIVE

Circulating erythropoietin (EPO) and vascular endothelial growth factor (VEGF) increase during hypoglycaemia and may represent protective hormonal counter-regulatory responses. We tested the hypothesis that low levels of EPO and VEGF are associated with a higher frequency of severe hypoglycaemia in a cohort of patients with type 1 diabetes.

DESIGN

Prospective observational follow-up study.

METHODS

Totally 219 patients with type 1 diabetes (41% females, age 46+/-13 years (mean+/-s.d.), duration of diabetes 21+/-12 years, and HbAlc 8.5+/-1.1%) were followed in a 1-year observational study. Plasma EPO and serum VEGF levels were measured at baseline with ELISA. Events of severe hypoglycaemia defined by third party assistance were recorded and validated in telephone interviews within 24 h.

RESULTS

Totally 235 episodes of severe hypoglycaemia (1.1 episodes per patient-year) were reported by 82 patients (37%). At baseline, plasma EPO was 8.6 (3.1-34.3) U/l (median (range)), and serum VEGF was 52.2 (6.6-337) pg/ml. The levels of EPO and VEGF were not associated with frequency of severe and mild hypoglycaemia. The levels of EPO were not associated with age, sex, duration of diabetes, body mass index, HbAlc, C-peptide level or hypoglycaemia awareness status. The levels of VEGF were positively associated with age and female sex.

CONCLUSIONS

Although several studies suggest that VEGF and EPO may affect brain function during hypoglycaemia, this study does not support random VEGF or EPO levels to determine future risk of severe hypoglycaemia in people with type 1 diabetes.