Objective: To compare the glycemic control of patients with type 1 diabetes treated in the U.S. and Canada.
Research design and methods: A large multicenter randomized clinical trial conducted in the U.S. and Canada was analyzed. Patients with type 1 diabetes, screened from 1983 to 1989 for enrollment in the Diabetes Control and Complications Trial (DCCT), were categorized as treated in the U.S. (n = 2,604) or Canada (n = 245). HbA(1c) levels were compared between U.S. and Canadian patients, both before and after adjustment for predictors of HbA(1c).
Results: In general, volunteers screened for the DCCT were highly educated and following healthy lifestyles. Canadians were somewhat younger (25 vs. 27 years of age, P = 0.002), less likely to be college educated (62 vs. 71%, P = 0.002), more likely to receive care through a family doctor (41 vs. 28%, P = 0.001), and had a higher frequency of out-patient visits (4 vs. 3 per year, P = 0.004). Despite these differences in health care delivery, the mean HbA(1c) at baseline was identical in the two countries (8.9 vs. 9.0, P = 0.40). Adjustment for demographic, lifestyle, and clinical predictors of HbA(1c) yielded similar findings (9.0 vs. 9.2, P = 0.15). Equal percentages of American and Canadian patients who were screened ultimately entered the trial (21 vs. 19%, P = 0.20), and those randomized to conventional care achieved similar mean HbA(1c) levels (9.1 vs. 9.2, P = 0.50).
Conclusions: Differences in care delivery patterns do not yield large differences in glycemic control for patients with type 1 diabetes who were recruited in the U.S. and Canada for a large randomized trial.