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J Diabetes Sci Technol. 2012 Sep 1;6(5):1114-22.

Feasibility of a bihormonal closed-loop system to control postexercise and postprandial glucose excursions.

Author information

1
Department of Internal Medicine, Academic Medical Center, Amsterdam, The Netherlands. a.c.vanbon@amc.nl

Abstract

BACKGROUND:

The aim of this pilot study was to test the feasibility of a bihormonal (glucagon and insulin) closed-loop (CL) system by challenging the system with two meals and 30 min exercise.

METHODS:

Ten patients with type 1 diabetes treated with continuous subcutaneous insulin infusion underwent a standardized protocol on three different occasions: 40 g carbohydrate breakfast followed 2 h later by 30 min of moderate-intensity exercise, followed 1.5 h later by a standardized 60 g carbohydrate lunch. An open-loop (OL) day served as control, the first CL day as tuning experiment, and the second CL day to compare with OL.

RESULTS:

The overall mean venous glucose was similar: 9 (5.4-13.5) mmol/liter in OL versus 8.7 (6.4-11.0) mmol/liter in CL, p = .74. The postbreakfast glucose concentrations tended to be lower in OL than in CL [9.5 (4.3-13.3) versus 11.4 (7-16.2) mmol/liter; p = .07] and higher in OL than in CL postlunch [9.4 (6.0-14.9) versus 7.7 (5.5-9.0) mmol/liter,p = .15]. The postexercise glucose concentrations were similar in OL and CL: 7.5 (4.6-13) versus 8.2 (5.5-13.1) mmol/liter; p = .45. In those patients coming in with baseline glucose above 7 mmol/liter, there was initial overinsulinization in CL. During OL, two hypoglycemic episodes occurred compared with four hypoglycemic episodes in three participants during CL. Glucagon seemed mostly effective in preventing hypoglycemia.

CONCLUSIONS:

Overall, CL glucose control was comparable to OL control, but there was overinsulinization in those patients with baseline glucose above 7 mmol/liter.

PMID:
23063038
PMCID:
PMC3570846
DOI:
10.1177/193229681200600516
[Indexed for MEDLINE]
Free PMC Article
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