Effect of automated bio-behavioral feedback on the control of type 1 diabetes

Abstract

Objective: To test the effect of an automated system providing real-time estimates of HbA(1c), glucose variability, and risk for hypoglycemia.

Research design and methods: For 1 year, 120 adults with type 1 diabetes (69 female/51 male, age = 39.1 [14.3] years, duration of diabetes 20.3 [12.9] years, HbA(1c) = 8.0 [1.5]), performed self-monitoring of blood glucose (SMBG) and received feedback at three increasingly complex levels, each continuing for 3 months: level 1--routine SMBG; level 2--adding estimated HbA(1c), hypoglycemia risk, and glucose variability; and level 3--adding estimates of symptoms potentially related to hypoglycemia. The subjects were randomized to feedback sequences of either levels 1-2-3 or levels 2-3-1. HbA(1c), symptomatic hypoglycemia, and blood glucose awareness were evaluated at baseline and at the end of each level.

Results: For all subjects, HbA(1c) was reduced from 8.0 to 7.6 from baseline to the end of study (P = 0.001). This effect was confined to subjects with baseline HbA(1c) >8.0 (from 9.3 to 8.5, P < 0.001). Incidence of symptomatic moderate/severe hypoglycemia was reduced from 5.72 to 3.74 episodes/person/month (P = 0.019), more prominently for subjects with a history of severe hypoglycemia (from 7.20 to 4.00 episodes, P = 0.008) and for those who were hypoglycemia unaware (from 6.44 to 3.71 episodes, P = 0.045). The subjects' ratings of the feedback were positive, with up to 89% approval of the provided features.

Conclusions: Feedback of SMBG data and summary SMBG-based measures resulted in improvement in average glycemic control and reduction in moderate/severe hypoglycemia. These effects were most prominent in subjects who were at highest risk at the baseline.

Trial registration: ClinicalTrials.gov NCT00315939.

Figures

Figure 1

A: Reduction of A1C (HbA1c) throughout the study. Level 1 feedback (SMBG alone) accounts for most of the improvements in HbA1c. The beneficial effects of the study are confined to those with baseline HbA1c >8.0; the rest of the subjects did not change their average glycemic control. The included significance levels refer to comparisons involving all subjects. B: Incidence of severe hypoglycemic was significantly reduced as a result of the study. However, the initial feedback from SMBG alone increased SH, and only more extensive feedback (levels 2 and 3) was able to reduce the incidence of SH. The included significance levels refer to comparisons involving all subjects. Although HbA1c can be improved by intensive SMBG, simultaneous improvement in both HbA1c and incidence of SH requires more extensive feedback to the patients. SH, severe hypoglycemia.