SAN DIEGO – The "low glucose suspend" insulin pump feature reduced the risk of hypoglycemia without any severe hyperglycemia or diabetic ketoacidosis in a German study of 21 children with type 1 diabetes.
Medtronic’s sensor-augmented insulin pump, the Paradigm Veo system, comprises an insulin pump, a continuous glucose monitor, and a component that first issues a "pre-alarm" if the sensor detects a reading below a preset level. If there is no response on the part of the patient and the glucose level continues to drop to a second preset level, the pump then alerts again and stops the basal insulin infusion for 2 hours or until there is a response. At 2 hours, the basal infusion resumes. If the glucose level is still too low at 4 hours after resumption, the cycle begins again.
The patient can interrupt the low glucose suspend (LGS) feature at any time, said Dr. Thomas Danne, head of the diabetes center for children and adolescents at the Kinderkrankenhaus auf der Bult in Hanover, Germany.
The Veo system is sold in 45 countries, including Canada, South Africa, Australia, and countries in Europe and Central and South America. It is not currently available in the United States. The U.S. Food and Drug Administration recently issued a guidance for manufacturers that are developing LGS systems, specifying the types of testing that must take place to address safety issues, including a concern that the device might overcorrect the hypoglycemia, resulting in hyperglycemia and/or diabetic ketoacidosis (DKA).
The Medtronic-sponsored study, conducted in three German pediatric diabetes centers, initially enrolled 24 patients aged 1-21 years (mean, 10.8 years) who had type 1 diabetes and had been on insulin pump therapy for an average of 3.6 years. Their mean baseline hemoglobin A1c was 7.8%. After patients wore the Veo without the LGS and pre-alerts for 2 weeks, those features were then turned on for the subsequent 6 weeks. The hypoglycemia alert was set at 75 mg/dL, and the LGS alert at 70 mg/dL. Complete data were available for 21 of the children.
A total of 1,298 alerts occurred, of which 853 (66%) were shorter than 5 minutes because the patients reacted immediately and there was no automatic interruption of insulin delivery. The frequency of alerts was 2.56 per patient per day, of which 78% occurred during the day (6:00 a.m.–10:00 p.m.). However, because the patients were far less likely to respond to the alarms while sleeping, the frequency of insulin delivery disruptions was far more common during the night (92 vs. 17, or 0.175 vs. 0.032 per patient per day), said Dr. Danne.
During the time of the LGS suspension, glucose levels rose an average of 35 mg/dL per hour, totaling 68.4 mg/dL per hour for the entire 120-minute period. The mean blood glucose level during the 6-week LGS period was 148 mg/dL, which was nearly identical to the 145 mg/dL recorded during the initial 2-week phase without the LGS. Standard deviations were 56 mg/dL and 55 mg/dL, respectively, and the time spent with hyperglycemia (defined as greater than 140 mg/dL) also was not significantly different (639 vs. 651 minutes). There were no cases of DKA during either time period, Dr. Danne reported.
But hypoglycemia rates did differ significantly. The amount of time spent with blood glucose levels less than 70 mg/dL was 58 minutes per day with the LGS, compared with 101 minutes without, a highly statistically significant difference (P = .002). Excursions of hypoglycemia below 40 mg/dL were also much lower with the LGS (0.13 vs. 0.28 per patient per day; P = .005) during both the daytime and overnight hours. The LGS cut the amount of time spent with blood glucose levels lower than both 70 mg/dL and 40 mg/dL by about 50%.
On a 7-point satisfaction survey, patients’ responses ranged from a high of 6.3 for "information on the Veo was valuable," to a low of 4.1 for "LGS prevented severe hypoglycemic episodes." The latter score was brought down by two very-well-controlled patients who didn’t feel that their risk for severe low blood glucose was high to begin with, Dr. Danne explained.
Dr. Danne received funding from Medtronic to conduct this trial.