Review Links Risk Factors in Type 1 Diabetes to Cognitive Impairment

A review published in Heliyon identified risk factors for cognitive impairment in patients with type 1 diabetes (T1D), including age, education, gender, and glycemic states.

This review used studies indexed in PubMed from between 2005 and 2021. All studies that were not related to dementia and risk factors in patients with T1D were excluded from this review. The researchers used 127 articles for this narrative review, which included both qualitative and quantitative studies of populations and animals; representative narrative reviews and systematic reviews were also included.

The researchers found multiple risk factors for cognitive impairment in those with T1D. Duration of diagnosis had an impact on cognitive impairment, as longer disease duration and younger age onset could be associated with aggravation of cognitive impairment or dementia. Children who did not receive diagnosis and treatment of T1D in a timely manner could have serious complications over time, especially in relation to cooperation and adherence to treatment. Studies also found that adults who had T1D had worse memory/language, executive function, attention, and abstraction ability than their counterparts without diabetes.

Higher level of education was also associated with less instances of cognitive impairment, as higher level of education often correlated with higher adherence to treatment and better control of blood sugar. Female patients with T1D were more likely to develop cognitive disfunction.

Exposure to glycemic extremes, including hyperglycemia and hypoglycemia, could also be a contributor to impaired cognition in patients with T1D. Inflammatory factors, oxidative stress, endothelial cell damage, mitochondrial dysfunction, and increased blood-brain barrier permeability were some reasons that hyperglycemia was associated with cognitive impairment in the selected studies.

Hypoglycemia was a more common condition in patients with T1D, as insulin therapy was found to increase the likelihood of hypoglycemia. Studies also found that children with hypoglycemic episodes had reduced reaction time and psychomotor speed. Recurrent hypoglycemia affected the integrity and function of neurons in 1 study. However, there were some studies that did not associate hypoglycemia with cognitive impairment.

Severe hypoglycemia (SH) was found in 30% to 40% of patients with T1D, making it the most serious adverse effect of insulin therapy. A study found that a history of SH or low fasting glucose could be associated with attention deficits in adolescents. Patients who had been previously exposed to moderate hypoglycemia and had new episodes of SH had severe cognitive impairment with the death of neurons in the hippocampus and frontal parietal lobes, according to 1 study. However, there are also studies that have found no relation between SH and cognitive impairment.

Hemoglobin A_1c (HbA_1c) was found to have a complicated association with cognitive impairment. A study found that controlling blood glucose could alleviate cognitive disfunction to some extent and a separate study found that 61.3% of patients without glycemic control had reported cognitive impairment. The researchers concluded that controlling blood sugar could be crucial to preventing cognitive impairment in glycemic states.

Overall, the researchers found that there were multiple risk factors for cognitive impairment in patients with T1D. They concluded that control of HbA_1c was important to reducing the occurrence of cognitive impairment, and adults with childhood onset of T1D would benefit most from these changes.

Reference

Jin CY, Yu SW, Yin JT, Yuan XY, Wang XG. Corresponding risk factors between cognitive impairment and type 1 diabetes mellitus: a narrative review. Heliyon. Published online August 3, 2022. doi:10.1016/j.heliyon.2022.e10073