High Rates of Cognitive Impairment in Type 2 Diabetes Linked to Age, HbA1c, and Vascular Risks: Meta-Analysis
China: A new systematic review and meta-analysis published in Frontiers in Endocrinology has shed light on the factors that increase the risk of mild cognitive impairment (MCI) in individuals with type 2 diabetes mellitus (T2DM). The study, led by Yi Zhao from the School of Postgraduate Education at Shandong Sport University in Jinan, China, and colleagues, offers insights into how clinical, lifestyle, and biochemical factors contribute to cognitive decline in this growing patient population.
MCI is an intermediate state between normal aging and dementia. Its identification is critical, as early interventions may help slow or even reverse cognitive deterioration. People living with T2DM face a particularly high risk of MCI due to metabolic dysfunction and vascular complications. While earlier meta-analyses tended to examine individual risk factors in isolation, this new study takes a more comprehensive approach, examining a wide range of variables that may interact to affect cognitive health.
The research team conducted a thorough review of five major databases, analyzing studies published between 2014 and 2024. Following the PRISMA guidelines, 30 eligible studies involving a total of 10,469 participants were included. Data were independently extracted and evaluated for quality, with statistical analysis performed using RevMan software.
The study revealed the following findings:
- The pooled prevalence of MCI in patients with T2DM was 44.1%.
- Advancing age (≥ 60 years) was strongly linked to an increased likelihood of MCI.
- Female sex was associated with a higher risk of MCI.
- Longer duration of diabetes (8–9 years) increases the likelihood of developing MCI.
- Elevated glycated hemoglobin (HbA1c > 9%) was associated with a higher risk of MCI.
- Lower education level (≤ 6 years) was linked to increased MCI risk.
- Smoking contributed significantly to the risk of developing MCI.
- Hypertension more than doubled the risk of MCI (OR = 2.25).
- Cardiovascular disease (CVD) was linked to an even higher risk of MCI (OR = 2.61).
- Elevated insulin resistance, as measured by HOMA-IR, increased the risk of MCI (OR = 1.95).
The study highlights the importance of integrated care approaches. The authors recommend that clinicians routinely conduct cognitive screening for high-risk patients, particularly older adults with long-standing diabetes, poor glycemic control, and vascular complications. They also suggest that maintaining HbA1c levels below 7% could help protect cognitive function, while patients with lower education levels may benefit from tailored educational support.
Despite its strengths, the study's findings are limited by the fact that most of the included research was conducted in Chinese populations, which may affect the generalizability of the results to other ethnic groups. Additionally, many of the studies were cross-sectional, limiting causal conclusions. The authors call for future large-scale, longitudinal studies across more diverse populations to validate these findings and deepen understanding of the links between T2DM and cognitive decline.
Reference:
Zhao, Y., Wang, H., Tang, G., Wang, L., Tian, X., & Li, R. (2025). Risk factors for mild cognitive impairment in type 2 diabetes: A systematic review and meta-analysis. Frontiers in Endocrinology, 16, 1617248. https://doi.org/10.3389/fendo.2025.1617248
