Background: Blood glucose monitoring is an important component of diabetes self-management for individuals with insulin-treated diabetes. Although patient-maintained logbooks are routinely used, glucose values may be inaccurately recorded or not recorded at all. Electronic logbooks may help overcome such problems. We conducted a randomized, controlled trial (RCT) to compare glycemic control in insulin-treated participants using integrated glucose meters and electronic logbooks (Electronic Group) with participants using conventional meters and paper logbooks (Paper Group), and to determine persistence of glycemic improvements during long-term observational follow-up. Methods: After a 4-week run-in, adult and pediatric participants (n = 205) with stable hemoglobin A1C (A1C) ≥8.0% were randomized, and their logbook data and A1C were monitored every 4 weeks for 16 weeks. After the RCT, patients selected their monitoring systems and resumed usual care. The four resulting subgroups, defined by whether patients continued or changed monitoring systems, were reassessed after 26-65 weeks. Results: During the RCT, mean A1C decreased -0.27% in the Paper Group and -0.35% in the Electronic Group. Repeated-measures analysis revealed that the mean decrease was significantly greater in the Electronic than the Paper Group (P = 0.022). From randomization through observational follow-up, participants consistently using integrated meters/logbooks had an A1C decrease of -0.36% (P = 0.008), whereas participants using conventional meters/logbooks throughout or switching meters returned to pre-enrollment A1C levels. Conclusions: Compared to conventional monitoring systems, use of an integrated meter and electronic logbook resulted in modest, but significant and sustained, improvement in A1C in insulin-treated patients with suboptimal glycemic control during an RCT and observational follow-up.