Prevention of nocturnal hypoglycemia using predictive alarm algorithms and insulin pump suspension.
OBJECTIVE
The aim of this study was to develop a partial closed-loop system to safely prevent nocturnal hypoglycemia by suspending insulin delivery when hypoglycemia is predicted in type 1 diabetes.


METHODS
Forty subjects with type 1 diabetes (age range 12-39 years) were studied overnight in the hospital. For the first 14 subjects, hypoglycemia (<60 mg/dl) was induced by gradually increasing the basal insulin infusion rate (without the use of pump shutoff algorithms). During the subsequent 26 patient studies, pump shutoff occurred when either three of five (n = 10) or two of five (n = 16) algorithms predicted hypoglycemia based on the glucose levels measured with the FreeStyle Navigator (Abbott Diabetes Care).


RESULTS
The standardized protocol induced hypoglycemia on 13 (93%) of the 14 nights. With use of a voting scheme that required three algorithms to trigger insulin pump suspension, nocturnal hypoglycemia was prevented during 6 (60%) of 10 nights. When the voting scheme was changed to require only two algorithms to predict hypoglycemia to trigger pump suspension, hypoglycemia was prevented during 12 (75%) of 16 nights. In the latter study, there were 25 predictions of hypoglycemia because some subjects had multiple hypoglycemic events during a night, and hypoglycemia was prevented for 84% of these events.


CONCLUSIONS
Using algorithms to shut off the insulin pump when hypoglycemia is predicted, it is possible to prevent hypoglycemia on 75% of nights (84% of events) when it would otherwise be predicted to occur.
Buckingham
Bruce
B
Department of Pediatric Endocrinology, Stanford University, Stanford, California, USA.
Chase
H Peter
HP
Dassau
Eyal
E
Cobry
Erin
E
Clinton
Paula
P
Gage
Victoria
V
Caswell
Kimberly
K
Wilkinson
John
J
Cameron
Fraser
F
Lee
Hyunjin
H
Bequette
B Wayne
BW
Doyle
Francis J
FJ
D000293:Adolescent; D000328:Adult; D000465:Algorithms; D001786:Blood Glucose / Q000187:drug effects / Q000378:metabolism; D002648:Child; D002940:Circadian Rhythm / Q000502:physiology*; D056902:Clinical Alarms; D003922:Diabetes Mellitus, Type 1 / Q000188:drug therapy*; D006801:Humans; D007003:Hypoglycemia / Q000139:chemically induced / Q000175:diagnosis / Q000517:prevention & control; D007004:Hypoglycemic Agents / Q000008:administration & dosage* / Q000009:adverse effects; D007328:Insulin / Q000008:administration & dosage* / Q000009:adverse effects; D007332:Insulin Infusion Systems; D007659:Ketones / Q000097:blood; D011237:Predictive Value of Tests; D055815:Young Adult
D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin; D007659:Ketones