BACKGROUND: Communication of blood glucose (BG) results between patients and health care providers (HCPs) is of established benefit and remains a critical part of the diabetes management process. Currently, HCPs typically receive BG data from patients at the time of clinic visits or by telephone. The Accu-Chek Acculink modem (Roche Diagnostics Corp., Indianapolis, IN) provides an additional and attractive option that can potentially facilitate this communication. METHODS: To assess the impact of modem transfer of BG, we studied 47 participants with diabetes enrolled in a diabetes education program. Subjects were randomized to weekly communication of BG data to their HCP by either telephone (n = 23) or modem (n = 24) for 4 weeks. Mean age (+/- SD) was 44 +/- 15 years, 62% were female, 74% used insulin, 53% had type 1 diabetes, and mean baseline glycosylated hemoglobin (A1C) was 8.8% (range 5.2-13.2%). RESULTS: There were no differences between groups in the amount of time the HCP spent analyzing BG data and communicating with patients (12.6 +/- 6.1 min/week in the telephone group and 11.5 +/- 5.1 min/week in the modem group) or in the number of patient and HCP attempts needed to make contact. There were similar improvements in A1C between groups (change of -0.4 +/- 0.7% in the telephone group and -0.9 +/- 1.4% in the modem group, P = 0.18). BG data provided by telephone had a 6% error rate, in contrast to modem-sent data, which were transmitted without error. CONCLUSIONS: Modem transfer of BG data can provide an accurate and clinically useful option for communication between patients and their HCP and has comparable effects on A1C.