OBJECTIVES: Diabetes guidelines recommend administration of bolus insulin within 30 minutes prior to mealtimes. However, lifestyle or eating habits may result in dosing outside of this period and poorer glycemic control, but few studies have explored this topic. Hence we investigated the association of timing of bolus insulin injection with glycemic control and adherence among type 2 diabetes mellitus (T2DM). METHODS:  Adults with T2DM were recruited to a self-reported online patient preference survey in 12 countries across North America, South America and Europe. Adherence was measured using an adapted Morisky Medication Adherence Scale (MMAS-8) questionnaire. RESULTS: In total 1,509 respondents reported using bolus insulin. Whilst the majority (864, 57%) always dosed bolus insulin before meals (pre-meal cohort), 354 (23%) always dosed during or after meals (post-meal cohort), and 265 (18%) dosed before, during or after meals (mixed cohort); 26 (2%) reported dosing at “other” times, and were excluded. The post-meal cohort was significantly younger and more likely to be degree-educated (both p<0.0001) and had a higher proportion (40%) with HbA ≥9%, compared to pre-meal (29%) and mixed cohorts (28%) (both p<0.0005). From the adapted MMAS-8, ‘forgetting to administer’ or ‘having difficulty remembering to take all insulin’ was more likely in the post-meal and mixed cohorts versus the pre-meal cohort (all p<0.05). 78% of respondents reported preferring bolus insulin that can be administered whenever convenient: before, during or after meals. CONCLUSIONS: When dosing bolus insulin, approximately 40% of patients fail to comply with guidelines for timing either all or part of the time, with higher risk of forgetting to take insulin. Patients dosing insulin post-meal are more likely to be younger and more educated, and have poor glycemic control (HbA1c ≥9%). Patient preference for bolus insulin with flexibility of dosing times should be considered in order to improve adherence and outcomes.