OBJECTIVES: In patients with type-2 diabetes (PwT2D) sufficient blood glucose control, also at an early stage, often cannot be reached by using oral antidiabetic drugs (OAD) alone so that the administration of insulin is necessary. Frequently, insulin therapy is initiated too late, which is mostly due to the patients' aversion to insulin. The aim of this survey was to investigate the influence of knowledge about insulin and the willingness to start using insulin treatment (WUI) in PwT2D on HbA1c not adequately controlled on OAD alone. METHODS: Study materials were sent out nation-wide to general practitioners by mail. The patient questionnaire covered the following topics: WUI; patients' reported well-being; perceived seriousness of T2D; perceived susceptibility to diabetic complications; expectations regarding beneficial and adverse effects of insulin; perceived incompatibility with daily routine. A 10-point rating scale (1= totally disagree / 10=totally agree) was used to document patient assessments. The assessments were analyzed descriptively. RESULTS: Out of 729 patients, 448 were treated with OAD only. In total, 222 had low WUI (1-5 points=group1/G1); 217 had high WUI (6-10 points=group2/G2); not answered n=9. A high percentage of patients indicated that they were aware of the seriousness of their T2D (G1=83%; G2=93% agreement). Yet, the majority of the patients did not agree that they had a severe stage of T2D (G1=79%; G2=73%). Patients with lower WUI showed less knowledge regarding insulin. HbA1c was comparable in both groups (7.3%±1,3). In G2, the number of patients reaching HbA1c <7% was higher by 11.6%. CONCLUSION: PwT2D have a “DEFICIT” in knowledge regarding insulin in general. On an individual basis, PwT2D often underestimate the severity of their diabetes. Higher level of knowledge is correlated with higher WUI and leads to better glycemic control.