Rapidly Raise Blood Sugar Will Aggravate Brain Damage After Severe Hypoglycemia in Rats

Correlation Between Diabetic Cognitive Impairment and Diabetic Retinopathy in Patients With T2DM by 1H-MRS

Objective: To explore the correlation between diabetic cognitive impairment (DCI) and diabetic retinopathy (DR) through examining the cognitive function and the metabolism of the cerebrum in Type 2 diabetes mellitus (T2DM) by ¹H-MRS.

Methods: Fifty-three patients with T2DM were enrolled for this study. According to the fundus examination, the patients were divided into the DR group (n = 26) and the T2DM without DR group (T2DM group, n = 27). Thirty healthy adults were selected as a control group (HC group, n = 30). Cognitive function was measured by Montreal Cognitive Assessment (MoCA). The peak areas of N-acetylaspartate (NAA), Cho-line (Cho), Creatine (Cr), and Myo-inositol (mI) as well as their ratios were detected by proton magnetic resonance spectroscopy (¹H-MRS). The difference analysis between the three groups was performed by one-way ANOVA. When p < 0.05, LSD-t was applied. A partial correlation analysis (with age as a covariate) was used to analyze the correlation between metabolites in the DR group and MoCA scores. Among all T2DM patients, Chi-square test age, gender, education level, BMI, SBP, DBP, FPG, HbA1c, TC, TG, HDL-C, LDL-C, DR, and DCI correlation were measured. Differences were statistically significant while P < 0.05.

Results: 1. The scores of MoCA in the DR group or in the T2DM group were significantly less than those in the HC group (F = 3.54, P < 0.05), and the scores of MoCA in the DR group were significantly less than those in the other groups (F = 3.61, P < 0.05). 2. There were significant differences for NAA in the bilateral hippocampus in DR patients, T2DM patients, and healthy controls (P < 0.05). 3. The NAA/Cr was significantly positively correlated with the score of MoCA in DR patients' left hippocampus (r = 0.781, P < 0.01). 4. Chi-square analysis found that there was a correlation between DR and DCI (x² = 4.6, df = 1, p = 0.032, plt: 0.05). There was no correlation between other influencing factors and DCI (P > 0.05).

Conclusion: DCI is closely correlated with the DR in patients with T2DM. Hippocampal brain metabolism may have some changes in two sides of NAA in patients with DR, ¹H-MRS may provide effective imaging strategies and methods for the early diagnosis of brain damage and quantitative assessment cognitive function in T2DM.

The neuroprotective effect and action mechanism of polyphenols in diabetes mellitus-related cognitive dysfunction

BACKGROUND

Diabetes mellitus (DM) is a complex and prevalent metabolic disorder worldwide. Strong evidence has emerged that DM is a risk factor for the accelerated rate of cognitive decline and the development of dementia. Though traditional pharmaceutical agents are efficient for the management of DM and DM-related cognitive decrement, long-term use of these drugs are along with undesired side effects. Therefore, tremendous studies have focused on the therapeutic benefits of natural compounds at present. Ample evidence exists to prove that polyphenols are capable to modulate diabetic neuropathy with minimal toxicity and adverse effects.

PURPOSE

To describe the benefits and mechanisms of polyphenols on DM-induced cognitive dysfunction. In this review, we introduce an updated overview of associations between DM and cognitive dysfunction. The risk factors as well as pathological and molecular mechanisms of DM-induced cognitive dysfunction are summarized. More importantly, many active polyphenols that possess preventive and therapeutic effects on DM-induced cognitive dysfunction and the potential signaling pathways involved in the action are highlighted.

CONCLUSIONS

The therapeutic effects of polyphenols on DM-related cognitive dysfunction pave a novel way for the management of diabetic encephalopathy.

A Systematic Review of Neuroprotective Strategies in the Management of Hypoglycemia

Severe hypogylcemia has been found to induce cerebral damage. While a number of illnesses can lead to hypoglycemic episodes, antidiabetic medications prescribed for glycemic control are a common cause. Considering the rising prevalence of diabetes mellitus in the population, we investigated neuroprotective strategies during hypoglycemia in the form of a systematic review in adherence to the PRISMA statement. A review protocol was registered in the PROSPERO database. A systematic literature search of PubMed, Web of Science, and CENTRAL was performed in September 2018. Based on a predefined inclusion protocol, results were screened and evaluated by two researchers. Both animal experiments and human studies were included, and their risk of bias was assessed with SYRCLE’s and the Cochrane risk of bias tools, respectively. Of a total of 16,230 results, 145 were assessed in full-text form: 27 articles adhered to the inclusion criteria and were qualitatively analyzed. The retrieved neuroprotective strategies could be categorized into three subsets: (1) Energy substitution, (2) hypoglycemia unawareness, and (3) other neuroprotective strategies. While on a study level, the individual results appeared promising, more research is required to investigate not only specific neuroprotective strategies against hypoglycemic cerebral damage, but also its underlying pathophysiological mechanisms.

Prevention of Severe Hypoglycemia-Induced Brain Damage and Cognitive Impairment With Verapamil

People with insulin-treated diabetes are uniquely at risk for severe hypoglycemia-induced brain damage. Because calcium influx may mediate brain damage, we tested the hypothesis that the calcium-channel blocker, verapamil, would significantly reduce brain damage and cognitive impairment caused by severe hypoglycemia. Sprague-Dawley rats (10 weeks old) were randomly assigned to one of three treatments: 1) control hyperinsulinemic (200 mU ⋅ kg^-1 ⋅ min^-1)-euglycemic (80-100 mg/dL) clamps (n = 14), 2) hyperinsulinemic-hypoglycemic (10-15 mg/dL) clamps (n = 16), or 3) hyperinsulinemic-hypoglycemic clamps, followed by a single treatment with verapamil (20 mg/kg) (n = 11). Compared with euglycemic controls, hypoglycemia markedly increased dead/dying neurons in the hippocampus by 16-fold and cortex by 14-fold. Verapamil treatment strikingly decreased hypoglycemia-induced hippocampal and cortical damage, by 87% and 94%, respectively. Morris Water Maze probe trial results demonstrated that hypoglycemia induced a retention, but not encoding, memory deficit (noted by both abolished target quadrant preference and reduced target quadrant time). Verapamil treatment significantly rescued spatial memory as noted by restoration of target quadrant preference and target quadrant time. In summary, a one-time treatment with verapamil after severe hypoglycemia prevented neural damage and memory impairment caused by severe hypoglycemia. For people with insulin-treated diabetes, verapamil may be a useful drug to prevent hypoglycemia-induced brain damage.

Mismatch between GLUTs and glucose levels causes neuronal damage during glucose fluctuations

Abnormal glucose levels damage the central nervous system, especially in case of rapid fluctuations. Even a single episode of glucose reperfusion can result in overt impairment of neurons. Oxidative stress plays an important role in this process, sharing properties with the pathophysiologic changes of glucose neurotoxicity. Glucose transporters (GLUTs) located in the brain are involved in direct glucose uptake by neurons. Instead of being insulin-sensitive, these transporters are regulated by glucose levels in the extracellular fluid, increasing their expression while glucose levels fall, to absorb more glucose. Therefore, we hypothesized that mismatch between altered GLUTs and sudden glucose level changes is responsible for neuronal damage during glucose fluctuations. Modulating hypoglycemia by increasing blood glucose slowly may improve the neurological outcomes of hypoglycemia.

Association of Hypoglycemia With Subsequent Dementia in Older Patients With Type 2 Diabetes Mellitus

Background

Studies have found conflicting evidence regarding the association of hypoglycemia with dementia. We evaluated an association of hypoglycemia with subsequent dementia in patients with type 2 diabetes.

Methods

This retrospective longitudinal cohort study used the Clinical Practice Research Datalink, an electronic medical records data from the United Kingdom, from 2003 to 2012. We included patients aged >65 years diagnosed with type 2 diabetes, with no prior diagnosis of dementia. Dementia was defined using diagnosis codes from medical records. All patients were followed from the date of initial diabetes diagnosis. To account for competing risk of death, we used Fine and Gray's competing risk model to determine the association of hypoglycemia with dementia while adjusting for potential confounders. Hypoglycemia was modeled as a time-dependent covariate.

Results

Of 53,055 patients, 5.7% (n = 3,018) had at least one hypoglycemia episodes. The overall incidence rate of dementia was 12.7 per 1,000 person-years. In the fully adjusted model that controlled for all confounders, the occurrence of at least one hypoglycemia episode was associated with 27% higher odds of subsequent dementia (hazard ratio = 1.27; 95% confidence interval = 1.06-1.51). The risk increased with the number of hypoglycemia episodes: one episode (hazard ratio = 1.26; 95% confidence interval = 1.03-1.54); two or more episodes (hazard ratio = 1.50; 95% confidence interval = 1.09-2.08).

Conclusions

Hypoglycemia is associated with a higher risk of dementia and may be responsible in part for the higher risk of dementia in patients with diabetes. Alternatively, hypoglycemia may be a marker for undiagnosed cognitive impairment, and we cannot rule out the possibility of reverse causation between hypoglycemia and dementia.