Glucose metabolism in the newborn can be a tricky thing to manage. Neonates can have significant fluctuation in their serum glucose in the first few days of life which can lead heels to look like pin cushions. How many times have you been asked as a physician if there is anything we can do to reduce the number of pokes? That something may have arrived at least in a feasibility study that could pave the way for this becoming the standard approach to hypo/hyperglycemia in the newborn. This is an important area to improve tightness of control as hyperglycemia has been associated in VLBW infants with such adverse outcomes as IVH, ROP and NEC.
Continuous glucose monitoring (CGM) with closed loop insulin delivery
The principle here is that a meter is inserted subcutaneously that detects blood glucose fluctuations and responds by either increasing infusion of dextrose for low glucose or delivery of insulin. The technology has been around for some time and used in the adult population but is relatively new in this population. I have written about it before in Continuous glucose monitoring in NICU may be around the corner. What follows is the latest pilot study to test this out coupled with glucose or insulin delivery in a closed loop system. The study in this case is out of Cambridge in the UK and entitled Feasibility of automated insulin delivery guided by continuous glucose monitoring in preterm infants .
What did they do?
The study was a pilot of 20 patients randomized to have an automated system to regulate glucose based on CGM data from 48-72 hours of age vs a paper based algorithm to manage dextrose or insulin infusion rates during the same period. The sample size was one of convenience to test the concept and the period was chosen to allow for time to recruit patients. The sensor used was an Enlite attached to a laptop with software capable of delivering infusion rates to two alaris pumps (one with 20% dextrose and the other with insulin). Target serum glucose levels were set to be between 4-8 mmol/L. The babies included were all under 1200g and had mean weights of 962g in the closed loop and 823g in the control arm.
The Results were fairly dramatic in my mind at least. A remarkable 91% of the infants in the closed loop system had glucose levels in the target range vs 26% in the control arm. Nutritional intakes and mean insulin dosing were not any different between groups. No harm in addition was noted from use of the CGMs. You don’t escape pokes all together though as the device does require q6h checks to calibrate and ensure it is reading properly. Every 6 hours is better though than every three for those with brittle control!
Tightly regulating blood glucose and avoiding both lows and highs has benefits on the low end to neurological preservation. On the high end some complications such as IVH, NEC and ROP may be avoided by better control. The challenge with the system as is at the moment is that it is not widely available. I am eager for a company out there to create software for mass distribution that would enable us to try this out. While the calibration is still required I can’t help but think this is an improvement over what we have at the moment. Stay tuned as I think this one is for real and will appear in NICUs sooner than you think!