Aims: Insulin pump self-management is important for glycaemic outcomes. We aimed to investigate associations between self-management factors and HbA1c. Methods: Adult insulin pump users with type 1 diabetes (n = 770) completed an online questionnaire. The latest HbA1c and demographics were extracted from national registries. Associations between HbA1c and self-management (use of advanced features, timing of infusion set change, timing of meal bolus, data-upload and pump settings adjustments) were investigated using backward selected linear regression models. Results: Of the 699 responders eligible for this study, 60% were women; the median age and diabetes duration were 49 and 25 years, respectively. Significant associations with HbA1c were found for changing infusion set every 0–4 days relative to 5–10 days (−5 mmol/mol (−0.4%), p = 0.003), and for never/rarely missing a bolus (−6 mmol/mol (−0.5%), p < 0.001) relative to often missing a bolus. Timing insulin 10–15 min before meal relative to after meal start was also associated with lower HbA1c (−3 mmol/mol (−0.3%), p = 0.023). Self-adjusting pump settings showed the strongest association with lower HbA1c (−6 mmol/mol (−0.6%), p < 0.001) relative to health care professionals doing all adjustments. Conclusion: Self-adjusting insulin pump settings, optimal timing and few omissions of meal boluses, and timely change of infusion set are associated with lower HbA1c.