OBJECTIVES: In a randomized controlled trial, adults with Type 1 diabetes and suboptimal glycemic control who received motivational enhancement therapy (MET) plus cognitive behavioral therapy (CBT) had a greater reduction in their 12-month hemoglobin A(1c) (Hb(A1c)) than those who received usual care (UC). We tested whether improvements in glycemic control persisted up to 4 years after randomization. METHODS: In the original trial, participants were randomized to UC (n = 121), 4 sessions of MET (n = 117), or 4 sessions of MET plus 8 sessions of CBT (n = 106). Of the 344 patients who participated in the original trial, 260 (75.6%) consented to take part in this posttrial study. A linear mixed model was fitted to available measurements to assess whether intervention effects on Hb(A1c) at 12 months were sustained at 2, 3, and 4 years. RESULTS: Estimated mean Hb(A1c) level was lower for participants in the two intervention arms when compared with UC at 2, 3, and 4 years, but none of the differences were statistically significant. At 4 years, estimated mean Hb(A1c) level for MET plus CBT was 0.28% (95% confidence interval = -0.22% to 0.77%) lower than that for UC, and estimated mean Hb(A1c) level for MET was 0.17% (95% confidence interval = -0.33% to 0.66%) lower than that for UC. CONCLUSIONS: There was no evidence of benefit for patients randomized to MET plus CBT at 2, 3, or 4 years. Larger studies are needed to estimate long-term treatment effects with greater precision. Current models of psychological treatments in diabetes may need to be intensified or include maintenance sessions to maintain improvements in glycemic control.