Diabetes is associated with increased risk of certain cardiovascular diseases, yet the causality remains to be determined. Meanwhile, given that first-degree relatives share 50% of genes, the effect of familial diabetes is also worthy of attention. Therefore, we sought to investigate the causal relations of individual or familial diabetes with eight cardiovascular diseases, including myocardial infarction, hypertension, atrial fibrillation, heart failure, cardiac death, pulmonary embolism, transient ischemic attack, and ischemic stroke.Applying two-sample Mendelian randomization, we selected instruments for genetic predisposition to individual or familial diabetes based on published genome-wide association studies. The primary analyses were conducted using the random-effects inverse-variance weighted method. We found that genetically predicted individual diabetes was causally associated with higher risks of myocardial infarction (odd ratio [OR] = 1.09; 95% confidence interval [CI]: 1.05-1.13; P < 0.0001), hypertension (OR = 1.08; 95% CI: 1.03-1.13; P = 0.0006), and ischemic stroke (OR = 1.10; 95% CI: 1.05-1.15; P < 0.0001). Genetically predicted paternal diabetes could increase the risk of ischemic stroke (OR = 1.16; 95% CI: 1.04-1.30; P = 0.0061). Genetically predicted maternal diabetes could increase the risk of myocardial infarction (OR = 1.18; 95% CI: 1.09-1.29; P = 0.0001). Genetically predicted siblings' diabetes was causally associated with higher risks of myocardial infarction (OR = 1.17; 95% CI: 1.08-1.27; P = 0.0001) and hypertension (OR = 1.19; 95% CI: 1.06-1.34; P = 0.0036). No significant differences were observed in other outcomes.This study supports causal effects of not only individual but also familial diabetes on the development of cardiovascular diseases, which will help realize the potential effect of family history in the prevention of cardiovascular diseases.Copyright © 2023. Published by Elsevier B.V.