Associations of glycaemia-related risk factors with dementia and cognitive decline in individuals with type 2 diabetes: A systematic review and meta-analysis.
Level 3 - non-randomized controlled study
Systematic review of prospective observational cohort studies
PubMed 40828960 · doi:10.1111/dme.70123
What was done
Systematic review and random-effects meta-analysis of prospective longitudinal studies (searching Embase and MEDLINE from January 2000 to October 2024) evaluating associations of glycaemia-related factors (hypoglycaemia, HbA1c, HbA1c variability, or diabetes duration) with cognitive decline, all-cause dementia, Alzheimer's disease (AD), or vascular dementia (VaD) in individuals with type 2 diabetes.
What was found
Forty studies with 7,076,724 individuals were included. Hypoglycaemia was significantly associated with a 49% higher risk of all-cause dementia and a 31% higher risk of AD, with no significant variation by age, sex, diabetes duration, smoking, follow-up length, or comorbid conditions (hypertension, kidney disease, dyslipidaemia, stroke; all p > 0.05). Hypoglycaemia frequency was positively linked to all-cause dementia (maximum HRs 2.36–2.60 in highest exposure groups). HbA1c showed positive risk gradients across individual studies (maximum significant HRs 1.40–3.88), with a pooled HR of 1.18 (95% CI 0.97, 1.45) across three meta-analysed studies. Both HbA1c variability and diabetes duration were significantly associated with increased dementia risk, while evidence linking glycaemia-related factors to cognitive decline was limited.
Why it matters
Demonstrates that severe glycaemic fluctuations, hypoglycaemic episodes, and disease duration are consistently linked to heightened long-term dementia risk in type 2 diabetes.
Limits
Based on observational longitudinal studies subject to potential residual confounding and reverse causation. Quantitative synthesis of HbA1c was limited to three studies yielding an estimate spanning null, and sparse data were available for non-dementia cognitive decline and specific dementia subtypes.
Cited by
- supports Type 2 diabetes is associated with an increased risk of developing Alzheimer's disease.