The Study
Cumulative effect of impaired fasting glucose on the risk of dementia in middle-aged and elderly people: a nationwide cohort study
This study found that people who had slightly high blood sugar levels over several years were a little more likely to get dementia later on, but it didn’t prove that the high sugar caused the dementia. It’s like noticing that people who eat a lot of candy also tend to get more cavities — but maybe they also brush their teeth less, so we can’t be sure the candy is the only reason.
Analysis score
Maximum 72 for a cohort study.
Where the score came from
Even if you don’t have diabetes, having slightly high blood sugar for years might slowly increase your risk of memory problems like Alzheimer’s.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 559 / 100
Quality score
Groups of people are followed over time to see who develops an outcome. Strong for identifying risk factors and associations, but cannot prove causation as firmly as RCTs.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — this means even small, repeated spikes in blood sugar, especially in people who aren’t overweight, could be quietly damaging the brain over time.
- 2People with high blood sugar (100–125 mg/dL) for 4 years had 7–14% higher risk of Alzheimer’s.
- 3This was true even if they never became diabetic.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Scientific Reports
Year
2023
Authors
Jin Yu, Kyu-na Lee, Hun‐Sung Kim, Kyung-do Han, Seung-Hwan Lee
Related Content
Claims (6)
Between 1991 and 2021, the percentage of adults aged 65 and older with dementia worldwide rose by 160%, and this rise was linked to higher levels of obesity and elevated fasting blood glucose.
Adults aged 40 and older who have had blood glucose levels in the prediabetic range (100–125 mg/dL) for four years have a 7% to 14% higher risk of developing dementia or Alzheimer’s disease, even when accounting for obesity, high blood pressure, and other metabolic conditions.
People with consistently elevated fasting blood glucose levels have a higher risk of developing dementia, and this risk is greater in those who are not obese than in those who are obese.
People with impaired fasting glucose have a higher risk of developing dementia, even if they never develop full diabetes.
People with impaired fasting glucose for four consecutive years have a 14% higher risk of developing Alzheimer’s disease than those with no exposure, and longer exposure is linked to greater risk.
Long-term elevated blood sugar levels are not linked to vascular dementia but are more strongly tied to Alzheimer’s disease than to brain blood vessel damage.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.