Researchers in Chicago, Illinois, using the Medtronic MiniMed Continuous Glucose Monitoring System (CGMS) conclude that the variable glucose profiles generated during endurance competitions such as marathons “indicate the need for intensive and accurate glucose monitoring.”
Six participants with diabetes were monitored during the 2001 Chicago Marathon. Each participant wore the CGMS-which measures glucose levels in the interstitial fluid-and used a LifeScan OneTouch Ultra meter for monitoring blood glucose.
The researchers found a correlation coefficient of 0.74 between the readings from the CGMS and those from the Ultra. A correlation coefficient, which ranges from 0 to 1, determines how closely two sets of numbers are related. The higher the number, the stronger the relationship. In addition, the CGMS “detected significant hypo- and hyperglycemic excursions during the marathon.”
Clinical adviser’s note: The auth-ors of this study emphasize that intensive monitoring is needed during endurance exercise. It is important to note that the currently available CGMS does not give the wearer access to the glucose results during the period being monitored; the multiple results are available only when electronically downloaded afterward. The next generations of continuous glucose monitoring systems are being developed to offer real-time glucose results.
Using the Concept of a Finite State Machine to Prevent and Manage Hypoglycemia
Using what is called a Finite State Machine, French researchers have broken blood-glucose levels into four “states” that lead to hypo-glycemia:
- Safety state, in which blood glucose is at a normal level
- Warning state, which triggers an “alarm” when blood-glucose levels are expected to reach a hypoglycemia threshold within a certain time
- Hypoglycemia, in which an alarm runs periodically until recovery
- Recovery state, in which blood-glucose levels begin to return to normal
From testing done on rats, the researchers conclude that the concept of a Finite State Machine can help to detect the transition between safety and warning states. The user would define the parameters of the hypoglycemia threshold and the timeline to trigger warnings during transition phases.
First Human Trials With a Novel Noninvasive, Nonoptical Continuous Glucose Monitoring System
Studying a new glucose monitoring technology based on radio wave impedance spectroscopy, German and Swiss researchers conclude that changes in blood glucose can be monitored “by varying radio-wave frequencies over a certain range optimized to measure the impact of glucose on the impedance pattern [of human skin and underlying tissue].”
Fifteen healthy volunteers were attached to a device called a Biostator, and their blood-glucose levels were increased rapidly to a hyperglycemic level (up to 300 mg/dl) using an infusion of the hormone somatostatin. Ten of the 15 showed a good correlation between their glucose readings and the readings of the Biostator.
Continuous Monitor Decreases Nighttime Hypos in Children With Well-Controlled Type 1 Without Sacrificing Metabolic Control
Connecticut researchers suggest that “repeated use of the CGMS in intensively treated youth with [type 1 diabetes] decreases the frequency of nocturnal hypoglycemic events without sacrificing overall diabetes control.”
Using the Medtronic MiniMed CGMS, the researchers followed 22 volunteers who wore the CGMS three times at six- to eight-week intervals.
Twenty-one of the volunteers were on insulin pump therapy. Before the study began, none were regularly monitoring blood-glucose levels during the night.
Adjustments in basal insulin delivery during the night were made based on the results of the first and second periods of CGMS monitoring. The percentage of all nighttime readings that were less than 40 mg/dl de-creased by more than 50 percent, the researchers report.
Transdermal Basal Insulin Delivery With a Patch
Studies are under way to develop a 24-hour insulin patch, which could provide a “painless, needle-free, basal-insulin delivery system for people with diabetes,” say researchers in Atlanta, Georgia.
Transdermal patches work on the same precept as the popular transdermal patches used in helping smokers kick the habit. Enlisting the help of five nondiabetic volunteers who wore a patch containing Humalog (insulin lispro) for 12 hours, the researchers discovered that the patch yielded a steady infusion of Humalog. When the patch was removed 12 hours later, the blood level of Humalog declined. The blood levels of Humalog were measured with a radioimmune assay specific for that insulin.