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Keywords:

  • closed-loop systems;
  • hyperglycaemia;
  • interruption of insulin infusion;
  • overnight hypoglycaemia

Diabet. Med. 27, 480–484 (2010)

Abstract

Aims  We assessed an extended interruption of subcutaneous insulin delivery during overnight closed-loop glucose control in children and adolescents with Type 1 diabetes (T1D).

Methods  In seven young subjects with T1D [age 14.2 ± 2.1 years, diabetes duration 6.9 ± 4.0 years, glycated haemoglobin (HbA1c) 8.0 ± 1.5%, body mass index (BMI) 21.4 ± 4.0 kg/m2, total daily insulin dose 0.9 ± 0.2 units/kg/day; mean ± sd) participating in overnight closed-loop glucose control studies, insulin delivery was interrupted for at least 90 min on the basis of predicted hypoglycaemia, low prevailing glucose levels or a too-steep decline in glucose levels.

Results  Insulin delivery was interrupted for 165 (105, 210) min [median, interquartile range (IQR)]. Plasma glucose was 6.2 ± 3.2 mmol/l at the time of interruption and 5.5 ± 2.0 mmol/l 105 min later (P = 0.15, paired t-test). Plasma glucose declined during the first hour of the interruption at a rate of 0.02 ± 0.03 mmol/l per min and reached a nadir of 5.2 ± 2.7 mmol/l; 105 min after the interruption, plasma glucose was increasing at a rate of 0.01 ± 0.03 mmol/l per min. When insulin delivery restarted, plasma glucose was 6.4 ± 2.2 mmol/l and peaked at 7.9 ± 2.1 mmol/l in 60 min (P = 0.01). Physiological levels of plasma insulin were measured throughout with a nadir of 119 ± 78 pmol/l.

Conclusions  A prolonged interruption of insulin delivery during overnight closed-loop glucose control to prevent hypoglycaemia was not associated with an increased risk of hyperglycaemia in young people with T1D.