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.

Liana K Billings,David Price,Christopher G Parkin

doi:10.1089/dia.2018.0163

Abstract

The DIAMOND study demonstrated that the addition of real-time continuous glucose monitoring (rtCGM) effectively lowers glycated hemoglobin (HbA1c) 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 HbA1c 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 HbA1c reductions among study participants within elevated baseline HbA1c 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 HbA1c 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 HbA1c 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 HbA1c was significantly greater in rtCGM participants compared to SMBG at all predefined baseline HbA1c levels at 12 and 24 weeks. Among the rtCGM participants, the change in HbA1c was numerically greatest at the highest baseline HbA1c subgroup (≥9.0%). Participants with elevated baseline HbA1c had improvements in glycemic status regardless of monitoring method. However, the magnitudes of improvements appeared greater among participants using rtCGM.

Highlights

Reducing glucose toxicity does not explain how interventions that modify behavior, such as real-time continuous glucose monitoring, would lower HbA1c from higher levels. rtCGM measures glucose and provides users with glucose numbers, glucose trends, and alerts for impending or actual hypoglycemia and hyperglycemia. It remains uncertain if insulin-treated individuals with the worst glucose control—who may have contributing factors such as poor numeracy skills, poor medication or monitoring adherence, psychosocial issues, eating disorders, or profound fear of hypoglycemia—would have similar improvement in blood glucose control driven by change in behavior with the rtCGM data compared to people who are closer to HbA1c goal
Among the 49 participants in the rtCGM group with a measured HbA1c ‡9.0%, 20 had hypertension and 4 had diagnosed coronary disease. The objective of these analyses was to determine whether and to what degree high baseline HbA1c values are associated with subsequent changes in glycemic status among MDItreated T1D and type 2 diabetes (T2D) participants
As reported in this study, a positive relationship between high baseline HbA1c values and improvements in glycemic status was observed among all study participants regardless of monitoring method

Summary

Introduction

RtCGM measures glucose and provides users with glucose numbers, glucose trends, and alerts for impending or actual hypoglycemia and hyperglycemia. Reducing glucose toxicity does not explain how interventions that modify behavior, such as real-time continuous glucose monitoring (rtCGM), would lower HbA1c from higher levels. It remains uncertain if insulin-treated individuals with the worst glucose control—who may have contributing factors such as poor numeracy skills, poor medication or monitoring adherence, psychosocial issues, eating disorders, or profound fear of hypoglycemia—would have similar improvement in blood glucose control driven by change in behavior with the rtCGM data compared to people who are closer to HbA1c goal

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Discussion

Conclusion