Outpatient assessment of determinants of glucose excursions in adolescents with type 1 diabetes: proof of concept

Abstract

Abstract Objective: Controlled inpatient studies on the effects of food, physical activity (PA), and insulin dosing on glucose excursions exist, but such outpatient data are limited. We report here outpatient data on glucose excursions and its key determinants over 5 days in 30 adolescents with type 1 diabetes (T1D) as a proof-of-principle pilot study.

Subjects and methods: Subjects (20 on insulin pumps, 10 receiving multiple daily injections; 15±2 years old; diabetes duration, 8±4 years; hemoglobin A1c, 8.1±1.0%) wore a continuous glucose monitor (CGM) and an accelerometer for 5 days. Subjects continued their existing insulin regimens, and time-stamped insulin dosing data were obtained from insulin pump downloads or insulin pen digital logs. Time-stamped cell phone photographs of food pre- and post-consumption and food logs were used to augment 24-h dietary recalls for Days 1 and 3. These variables were incorporated into regression models to predict glucose excursions at 1-4 h post-breakfast.

Results: CGM data on both Days 1 and 3 were obtained in 57 of the possible 60 subject-days with an average of 125 daily CGM readings (out of a possible 144). PA and dietary recall data were obtained in 100% and 93% of subjects on Day 1 and 90% and 100% of subjects on Day 3, respectively. All of these variables influenced glucose excursions at 1-4 h after waking, and 56 of the 60 subject-days contributed to the modeling analysis.

Conclusions: Outpatient high-resolution time-stamped data on the main inputs of glucose variability in adolescents with T1D are feasible and can be modeled. Future applications include using these data for in silico modeling and for monitoring outpatient iterations of closed-loop studies, as well as to improve clinical advice regarding insulin dosing to match diet and PA behaviors.

Figures

FIG. 1.

Example of temporal relationship of insulin doses, carbohydrate (CHO), and physical activity (PA) with continuous glucose monitoring (CGM): region 1, multiple boluses for hyperglycemia; region 2, vigorous PA; region 3, hypoglycemia with CHO treatment and cessation of PA; and region 4, rebound hyperglycemia. Color images available online at www.liebertonline.com/dia