Baseline Glycated Hemoglobin Values Predict the Magnitude of Glycemic Improvement in Patients with Type 1 and Type 2 Diabetes: Subgroup Analyses from the DIAMOND Study Program

Abstract

The DIAMOND study demonstrated that the addition of real-time continuous glucose monitoring (rtCGM) effectively lowers glycated hemoglobin (HbA_1c) in patients with type 1 (T1D) and type 2 diabetes (T2D), treated with multiple daily injections (MDI). This post hoc analysis investigated whether DIAMOND study participants at progressively higher baseline HbA_1c levels benefit from using rtCGM. We examined outcomes data from a large, randomized, controlled trial of MDI-treated participants with T1D (N = 158) and T2D (N = 158), comparing monitoring by rtCGM versus self-monitoring of blood glucose (SMBG). The primary outcome was the magnitude of HbA_1c reductions among study participants within elevated baseline HbA_1c levels (≥8.0%-10.0%, ≥8.5%-10.0%, and ≥9.0%-10.0%). Analyses were performed on three subgroups: T1D, T2D, and combined T1D/T2D. The full T1D analysis population had a mean baseline HbA_1c value of 8.6 ± 0.6% (range 7.5%-9.9%), randomized to rtCGM (n = 105) or control (n = 53). The full T2D analysis population had a mean baseline HbA_1c value of 8.5 ± 0.6% (range 7.5%-9.9%), randomized to rtCGM (n = 79) or control (n = 79). Participants had improvements in glycemic status regardless of monitoring method. In the three subgroups, the change in HbA_1c was significantly greater in rtCGM participants compared to SMBG at all predefined baseline HbA_1c levels at 12 and 24 weeks. Among the rtCGM participants, the change in HbA_1c was numerically greatest at the highest baseline HbA_1c subgroup (≥9.0%). Participants with elevated baseline HbA_1c had improvements in glycemic status regardless of monitoring method. However, the magnitudes of improvements appeared greater among participants using rtCGM.