To compare the glycemic control of patients with type 1 diabetes treated in the U.S. and Canada.
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).
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).
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.