Background: The influence of diabetes mellitus (DM) on recurrent in-stent restenosis (ISR) of femoropopliteal arteries remains understudied. We investigated whether DM has an impact on recurrent restenosis after femoropopliteal stenting in patients included in the dRug-coatEd balloon angioPlasty for femoropopliteAl In-stent Restenosis (REPAIR) cooperation. Patients and methods: The REPAIR cooperation pooled the patient-level data from 3 randomized trials in which patients with ISR of femoropopliteal arteries received either drug-coated balloon (DCB) or plain balloon angioplasty. For this analysis, patients were divided in two groups based on whether they had or had not a DM diagnosis at the time of enrollment. The primary outcome was target lesion revascularization (TLR). The main secondary outcome was recurrent ISR. Other outcomes of interest were death, Rutherford class improvement and ankle-brachial index at follow-up. Results: 256 patients (DM, n=99 vs. non-DM, n=157) with 12-month follow-up were included in the analysis. Compared to non-DM patients, DM patients displayed no difference in terms of TLR [adjusted hazard ratio (95% Confidence intervals): 0.96 (0.55, 1.69), p=0.89] and recurrent ISR [1.04 (0.61, 1.77), p=0.88], whilst mortality was higher [9.38 (1.06, 83.11), p=0.044]. There were no differences between groups with respect to other secondary outcomes. The percutaneous treatment with DCB as compared to plain balloon angioplasty significantly reduced the risk of TLR and recurrent ISR without an excess risk of death irrespective of DM (p for interaction ≥0.70). Conclusions: In patients with femoropopliteal ISR, diabetes has a neutral effect on the risk of recurrence, but increases mortality at 12-month follow-up. DCB as compared to plain balloon angioplasty is associated with superior efficacy without trade-off in safety, regardless of diabetes.