Determinants of successful glycemic control among participants in the BARI 2D trial: a post-hoc analysis

Abstract

Objective: The BARI 2D trial compared insulin provision (IP) versus insulin sensitization (IS) for the primary outcome of total mortality in participants with T2DM and cardiovascular disease (CVD). In this analysis we examine baseline characteristics that are associated with successful long-term glycemic control.

Research design and methods: In a 2×2 factorial design, 2368 participants were randomized to either IP or IS therapy, and to either prompt revascularization with medical therapy or medical therapy alone. Successful long-term glycemic control (success) was defined by simultaneously meeting 1) a mean HbA1c level of <7.0% after each participant's third year of follow-up period, and 2) adherence with medications only from the assigned glycemic treatment arm during >80% of the BARI 2D follow-up. The association between baseline variables and success was determined using unadjusted and adjusted logistic regression models.

Results: 1917 participants (962 IP and 955 IS participants) had sufficiently long follow-up and data for this analysis. Among these IP and IS participants, 235 and 335 participants met both criteria of success, respectively (p<0.001). Those not on insulin at entry had higher odds of success (OR 2.25; CI 1.79-2.82) when treated with IS versus IP medications, irrespective of baseline HbA1c levels. Younger age, shorter duration of T2DM, and lower HbA1c at baseline were also each independently associated with higher success when treated with IS versus IP medications.

Conclusion: Patients similar to those in the BARI 2D trial may have a higher chance of achieving success with IS versus IP medications if they are younger, have shorter duration of T2DM, have lower HbA1c levels, have moderate or strenuous physically activity, and are not on insulin. In contrast, increasing age, longer duration of T2DM, higher HbA1c, and insulin therapy are associated with increased chance of success if treated with IP medications.

Keywords: Cardiovascular disease; Plasma insulin levels; Predictors of glycemic control.

Figure 1

Flow-chart of participants included in the analysis.

Figure 2a. Comparison (IS vs. IP) of successful long–term glycemic control

Odds ratio (IS/IP) estimates for participants not on insulin at baseline *testing whether difference in odds ratio estimates is statistically significant **multiply by 6.945 to obtain pmol/L

Figure 2b. Comparison (IS vs. IP) of successful long–term glycemic control

Odds ratio (IS/IP) estimates for participants not on insulin at baseline *testing whether difference in odds ratio estimates is statistically significant **multiply by 6.945 to obtain pmol/L

Figure 3. Baseline Characteristics Associated with Higher Rates of Success for Glycemic Control

A more detailed description of some of the characteristics is given in the text. At entry, the average age was 62 years, duration of diabetes was 10 years, 27% were being treated with insulin, and HbA1c averaged 7.7%; status of physical activity was classified as moderate or strenuous versus sedentary or mild.