Aim: The aim of the study was to evaluate the relationship between smoking status and the incidence of microvascular complications in patients with type 1 diabetes (DM1), treated with intensive functional insulin therapy (IFIT) from the onset of the disease. Methods: 81 participants (51 men, 30 women) of Poznan Prospective Study (PoProStu) with mean age of 34.0 +/- 6.4 years were included in this analysis. Patients were observed for 10.0 +/- 1.5 years. Evaluation of microvascular complications of diabetes, such as retinopathy, diabetic kidney disease and neuropathy was performed. Patients were divided into two groups depending on the smoking status: smokers and non-smokers. Results: In the group of smokers (n = 36) in comparison with patients who had never smoked (n = 45) any microangiopathy (58.3% vs 33.3%, p = 0.02), retinopathy (44.4% vs 20%, p = 0.02), diabetic kidney disease (47.2% vs 24.4%, p = 0.03) and neuropathy (25% vs 4.4%, p = 0.02) were found more often. A significant relationship, adjusted for age, sex, duration of diabetes, presence of hypertension and HbA1c between smoking and neuropathy and retinopathy was revealed [OR 10.16 (95%CI 1.59-64.95); p = 0.01 and OR 3.50 (95%Cl 1.01-12.12); p = 0.04, respectively]. Conclusion: The results show that in patients with DM1, there is a strong relationship between smoking and the diabetic microvascular complications, especially with neuropathy, despite treatment from the initial diagnosis with intensive insulin therapy. (c) 2014 Elsevier Inc. All rights reserved.