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Introduction: Observational studies have reported a higher risk of dementia in individuals with type 2 diabetes and high glucose concentrations have been associated with dementia independent of type 2 diabetes. However, is not known whether glucose per se has a causal effect on risk of dementia. Hypothesis: High plasma glucose due to genetic variation is causally associated with risk of Alzheimer's dementia, vascular dementia, and unspecified dementia in the general population. Methods: We examined observational associations of plasma glucose concentration with risk of disease; genetic variants with plasma glucose concentrations; and genetic variants with risk of disease as an indication of a causal effect of high plasma glucose on disease, using a Mendelian randomization design largely free of confounding and reverse causation in 125,875 individuals from the Copenhagen General Population Study and the Copenhagen City Heart Study. Results: In observational multifactorially adjusted analyses hazard ratio for Alzheimer's dementia was 1.18 (95% confidence interval: 0.89-1.56; p=0.25), for vascular dementia 1.74 (1.02-2.96; p=0.043), and 1.50 (1.15-1.95; p=0.003) for unspecified dementia in individuals with a glucose above 9 mmol/L versus between 5-6 mmol/L. Corresponding hazard ratios were 1.13 (0.96-1.32; p=0.14), 1.66 (1.25-2.21; p<0.001) and 1.39 (1.21-1.60; p<0.001) in individuals with type 2 diabetes versus without. A weighted allele score of glucose increasing alleles was associated with a 4.1% higher plasma glucose. In genetic, causal analyses a 1 mmol/L higher plasma glucose had risk ratios of 0.85 (0.70-1.04; p=0.11) for Alzheimer's dementia, of 1.03 (0.74-1.89; p=0.87) for vascular dementia, and of 1.17 (0.64-2.13; p=0.61) for unspecified dementia. Summary level data from the International Genomics of Alzheimer's Project using Egger Mendelian randomisation analysis gave a risk ratio for Alzheimer's dementia of 1.09 (0.60-1.96; p=0.79). Conclusions: Genetically high plasma glucose had no causal effect on risk of Alzheimer's dementia, vascular dementia, or unspecified dementia, suggesting that the increased observational risk of vascular and unspecified dementia is likely due to confounding and/or reverse causation. [ABSTRACT FROM AUTHOR]

Background: End-stage renal disease is associated with a high risk of cardiovascular events. It is unknown, however, whether mild-to-moderate kidney dysfunction is causally related to coronary heart disease (CHD) and stroke., Methods: Observational analyses were conducted using individual-level data from 4 population data sources (Emerging Risk Factors Collaboration, EPIC-CVD [European Prospective Investigation into Cancer and Nutrition-Cardiovascular Disease Study], Million Veteran Program, and UK Biobank), comprising 648 135 participants with no history of cardiovascular disease or diabetes at baseline, yielding 42 858 and 15 693 incident CHD and stroke events, respectively, during 6.8 million person-years of follow-up. Using a genetic risk score of 218 variants for estimated glomerular filtration rate (eGFR), we conducted Mendelian randomization analyses involving 413 718 participants (25 917 CHD and 8622 strokes) in EPIC-CVD, Million Veteran Program, and UK Biobank., Results: There were U-shaped observational associations of creatinine-based eGFR with CHD and stroke, with higher risk in participants with eGFR values <60 or >105 mL·min -1 ·1.73 m -2 , compared with those with eGFR between 60 and 105 mL·min -1 ·1.73 m -2 . Mendelian randomization analyses for CHD showed an association among participants with eGFR <60 mL·min -1 ·1.73 m -2 , with a 14% (95% CI, 3%-27%) higher CHD risk per 5 mL·min -1 ·1.73 m -2 lower genetically predicted eGFR, but not for those with eGFR >105 mL·min -1 ·1.73 m -2 . Results were not materially different after adjustment for factors associated with the eGFR genetic risk score, such as lipoprotein(a), triglycerides, hemoglobin A1c, and blood pressure. Mendelian randomization results for stroke were nonsignificant but broadly similar to those for CHD., Conclusions: In people without manifest cardiovascular disease or diabetes, mild-to-moderate kidney dysfunction is causally related to risk of CHD, highlighting the potential value of preventive approaches that preserve and modulate kidney function.