- Diabetes mellitus (DM), pre-DM, and glycaemic markers were associated with risk for cognitive impairment and dementia, but pioglitazone (Actos) appeared protective.
Why this matters
- Lack of effective prevention and treatment interventions for dementia.
- Diabetes conferred elevated risks for cognitive disorders (relative risk [RR]; 95% CI):
- Global cognitive decline (1.25; 1.12-1.39).
- Executive function decline (1.44; 1.23-1.69).
- Memory function impairment (1.27; 1.16-1.39).
- Mild cognitive impairment (1.49; 1.26-1.77).
- Progression from mild cognitive impairment to dementia (1.91; 1.54-2.36).
- All-cause dementia (1.43; 1.33-1.53).
- Alzheimer’s disease (1.43; 1.25-1.62).
- Vascular dementia (1.91; 1.61-2.25).
- Prediabetes conferred elevated risks for cognitive disorders (RR; 95% CI):
- Dementia (1.18; 1.02-1.36).
- Alzheimer’s disease (1.36; 1.09-1.70).
- Vascular dementia (1.47; 1.01-2.15).
- Associations also seen for fasting plasma glucose and insulin, 2-hour postload glucose, glycosylated haemoglobin.
- Among diabetic patients, risk for dementia (RR; 95% CI):
- Lower with pioglitazone (0.53; 0.39-0.73).
- Similar with metformin (Glucophage, others; 0.89; 0.75-1.06).
- Systematic review of 144 studies; meta-analysis of 122 studies having more than 4.5 million participants.
- Main outcomes: cognitive disorders.
- Funding: National Key R&D Program of China; Shanghai Municipal Science and Technology Major Project; others.
- Some studies possibly missed.
- Small numbers for certain analyses.
- Variation controlling for confounders.
- Low-quality evidence for some associations.