Microglia Involvement into Acute and Chronic Brain Damage in Diabetic Rats: Impact of GLP-1RA and SGLT-2i

Association of Metformin use with risk of dementia in patients with type 2 diabetes: A systematic review and meta-analysis

AIM

There is ongoing debate concerning the association of metformin with the risk of dementia in type 2 diabetes mellitus (T2DM). This study was conducted to evaluate the impact of metformin therapy on dementia in patients with T2DM.

MATERIALS AND METHODS

PubMed, Embase, Cochrane Library, Web of Science and the ClinicalTrials.gov website were searched until 9 April 2024. Cohort studies investigating the effects of metformin therapy compared with other antidiabetic drugs or no therapy in T2DM were included. The hazard ratio (HR) and the 95% confidence interval (CI) were computed using the random effects model.

RESULTS

Twenty cohort studies (24 individual comparisons) involving 3 463 100 participants were identified. A meta-analysis revealed that people with T2DM who take metformin are linked to a lower incidence of all-cause dementia compared to non-user (n = 17, HR = 0.76, 95% CI = 0.65-0.91, p = 0.002, I2 = 98.9%) and sulfonylureas (n = 5, HR = 0.88, 95% CI = 0.85-0.90, p < 0.001, I2 = 9.7%), but not to thiazolidinedione (n = 2, HR = 0.53, 95% CI = 0.08-3.41, p = 0.503, I2 = 92.7%). Additionally, metformin showed favourable effects in non-specified T2DM (n = 19, HR = 0.75, 95% CI = 0.64-0.89), but not in newly diagnosed T2DM (n = 5, HR = 1.01, 95% CI = 0.81-1.27).

CONCLUSION

Metformin might correlate with a lower dementia incidence in people with T2DM. However, it is crucial to interpret these results with caution considering the high heterogeneity.

SGLT-2 Inhibitors' and GLP-1 Receptor Agonists' Influence on Neuronal and Glial Damage in Experimental Stroke

Background: SGLT-2 inhibitors (SGLT-2i) and GLP-1 receptor agonists (GLP-1RA) have demonstrated nephro- and cardioprotective effects, but their neuroprotective properties, especially concerning stroke severity, and mechanisms are not unambiguous. We aimed to study the influence of SGLT-2i with different selectivity and GLP-1RA on brain damage volume and neurological status in non-diabetic and diabetic rats and to investigate the underlying mechanisms. Methods: Non-diabetic Wistar rats were divided into five groups (n = 10 each) and received empagliflozin, canagliflozin, or dulaglutide as study drugs and metformin as comparison drug. Control animals were administered 0.9% NaCl for 7 days before stroke. At 48 h after stroke, we assessed neurological deficit, neuronal and astroglial damage markers, and brain damage volume. We also modeled type 2 DM in Wistar rats using the high-fat diet+nicotinamide/streptozotocin method and established similar treatment groups. After 8 weeks, rats were subjected to stroke with further neurological deficit, neuroglial damage markers, and brain necrosis volume measurement. Results: In non-diabetic rats, all the drugs showed an infarct-limiting effect; SGLT-2i and dulaglutide were more effective than metformin. DULA improved neurological status compared with MET and SGLT-2i treatment. All the drugs decreased neurofilament light chains (NLCs) level and neuronal damage markers, but none of them decreased the glial damage marker S100BB. In DM, similarly, all the drugs had infarct-limiting effects. Neurological deficit was most pronounced in the untreated diabetic rats and was reduced by all study drugs. All the drugs reduced NLC level; dulaglutide and empagliflozin, but not canagliflozin, also decreased S100BB. None of the drugs affected neuron-specific enolase. Conclusions: SGLT-2i and GLP-1RA are neuroprotective in experimental stroke. GLP-1RA might be more effective than SGLT-2i as in non-diabetic conditions it influences both brain damage volume and neurological status. All study drugs decrease neuronal damage, while GLP-1RA and highly selective SGLT-2i EMPA, but not low-selective CANA, also have an impact on neuroglia in diabetic conditions.