Forty-one studies (sample size 16 to 1,622 participants) were included in the review: 26 randomised controlled trials (22 were crossover studies); 12 prospective studies (11 were single-group before/after studies); two cross-sectional studies; and one retrospective study. Follow-up ranged from two weeks to five years.
Preference (29 studies): In 28 studies most patients (>66%) preferred insulin pen devices to vial or syringe or chose and/or were willing to continue treatment with insulin pen devices instead of vial and syringe. In one study there was a similar preference for insulin pen and for vial and syringe use.
Acceptability (12 studies): In 10 studies, most patients (>75%) reported greater acceptance of insulin pen devices compared to vial and syringe. Two studies did not reported greater acceptability with pen devices compared to vial and syringe.
Pain (nine studies): Eight studies reported that most patients (>50%) experienced less pain with a pen device than a vial and syringe.
Quality of life (eight studies): Three studies found a greater improvement in quality of life in patients who used an insulin pen device compared with those who used a vial and syringe. Three studies found no statistically significant difference in quality of life after using an insulin pen devices compared with using a vial and syringe. Two studies had mixed results in difference aspects of quality of life.
Satisfaction (seven studies): Five studies found that most patients (>76%) experienced higher treatment satisfaction from using an insulin pen device compared with a vial and syringe. Two studies found no significant difference in satisfaction between insulin pen device use and vial and syringe.
Convenience, handling, dosing and ease of use (10 studies): Eight studies found that most patients (56% to 100%) found insulin pen devices more convenient to use than vial and syringe. Two studies evaluated handling and dosing. The authors reported that in one study, 92% of patients considered the pen device easier to use. All nine studies that evaluated ease of use found that most patients (≥61%) found the insulin pen device easier to use than vial and syringe.