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Noninvasive Glucose Monitoring
CLINICAL QUESTION: How accurate is noninvasive glucose monitoring?
BACKGROUND: Tight glycemic control has been shown to improve diabetic outcomes, but current methods for monitoring blood glucose levels are painful and invasive. This trial compares traditional finger-stick glucose monitoring with the non- invasive technique of transdermal iontophoresis.
POPULATION STUDIED: A total of 92 adults with either type 1 or type 2 diabetes were enrolled from 2 diabetes centers and 3 contract research organizations. The mean age was 42 years, and 60% were women. The study population seems similar to that of a typical family practice with respect to the accuracy of noninvasive glucose monitoring.
STUDY DESIGN AND VALIDITY: The noninvasive Glucowatch biographer was compared with finger-stick capillary glucose measurements. After calibration by a single finger-stick measurement, participants wore up to 2 biographers for 12 to 15 hours while getting 2 finger-sticks per hour. Diet and insulin regimens were altered to provide a wide range of glucose levels (40-400 mg/dL).
OUTCOMES MEASURED: The major outcomes assessed were the correlation between biographer and finger-stick measures and the clinical significance of errors. Adverse effects of the biographer were also noted. Other patient-oriented outcomes, such as cost, patient satisfaction, reduction of symptoms, complications of hypoglycemia and hyperglycemia, and ease of use were not addressed.
RESULTS: Biographer readings lagged behind blood glucose measurements by a mean of 18 minutes. There was close tracking of blood glucose levels over a range of 40 to 400 mg/dL for up to 12 hours after a single calibration, and 97% of the biographer readings were associated with a finger-stick reading that was therapeutically equivalent. The average difference between measurements was 15.6%. The highest frequency of clinically significant errors was seen at blood glucose levels below 70 mg/dL; nearly one half of finger-stick measures below 70 mg/dL were read by the biographer as higher. Mild skin irritation occurred at the iontophoresis site.
Noninvasive glucose monitoring using transdermal iontophoresis can be used to track capillary glucose levels. Clinicians should understand, however, that this report is still very preliminary, and important patient-oriented outcomes have not been assessed. At a clinical level, the need for calibration, the relatively poor performance with low blood sugars, and skin irritation after 12 to 15 hours of use need further exploration. More important, this research was done by the manufacturing company on a single set of patients over a 1-day period in a laboratory environment with a suboptimal gold standard.
Although the allure of noninvasive monitoring is great, it is important to think carefully about the clinical settings in which it would be used. For patients with type 2 diabetes, the major concern has been long-term control, which may be better measured using hemoglobin A 1C every 3 months. In terms of improving clinical outcomes, there is increasing evidence that smoking cessation, low- density lipoprotein reduction, blood pressure control, and aspirin use may be much more important than blood glucose control.
CLINICAL QUESTION: How accurate is noninvasive glucose monitoring?
BACKGROUND: Tight glycemic control has been shown to improve diabetic outcomes, but current methods for monitoring blood glucose levels are painful and invasive. This trial compares traditional finger-stick glucose monitoring with the non- invasive technique of transdermal iontophoresis.
POPULATION STUDIED: A total of 92 adults with either type 1 or type 2 diabetes were enrolled from 2 diabetes centers and 3 contract research organizations. The mean age was 42 years, and 60% were women. The study population seems similar to that of a typical family practice with respect to the accuracy of noninvasive glucose monitoring.
STUDY DESIGN AND VALIDITY: The noninvasive Glucowatch biographer was compared with finger-stick capillary glucose measurements. After calibration by a single finger-stick measurement, participants wore up to 2 biographers for 12 to 15 hours while getting 2 finger-sticks per hour. Diet and insulin regimens were altered to provide a wide range of glucose levels (40-400 mg/dL).
OUTCOMES MEASURED: The major outcomes assessed were the correlation between biographer and finger-stick measures and the clinical significance of errors. Adverse effects of the biographer were also noted. Other patient-oriented outcomes, such as cost, patient satisfaction, reduction of symptoms, complications of hypoglycemia and hyperglycemia, and ease of use were not addressed.
RESULTS: Biographer readings lagged behind blood glucose measurements by a mean of 18 minutes. There was close tracking of blood glucose levels over a range of 40 to 400 mg/dL for up to 12 hours after a single calibration, and 97% of the biographer readings were associated with a finger-stick reading that was therapeutically equivalent. The average difference between measurements was 15.6%. The highest frequency of clinically significant errors was seen at blood glucose levels below 70 mg/dL; nearly one half of finger-stick measures below 70 mg/dL were read by the biographer as higher. Mild skin irritation occurred at the iontophoresis site.
Noninvasive glucose monitoring using transdermal iontophoresis can be used to track capillary glucose levels. Clinicians should understand, however, that this report is still very preliminary, and important patient-oriented outcomes have not been assessed. At a clinical level, the need for calibration, the relatively poor performance with low blood sugars, and skin irritation after 12 to 15 hours of use need further exploration. More important, this research was done by the manufacturing company on a single set of patients over a 1-day period in a laboratory environment with a suboptimal gold standard.
Although the allure of noninvasive monitoring is great, it is important to think carefully about the clinical settings in which it would be used. For patients with type 2 diabetes, the major concern has been long-term control, which may be better measured using hemoglobin A 1C every 3 months. In terms of improving clinical outcomes, there is increasing evidence that smoking cessation, low- density lipoprotein reduction, blood pressure control, and aspirin use may be much more important than blood glucose control.
CLINICAL QUESTION: How accurate is noninvasive glucose monitoring?
BACKGROUND: Tight glycemic control has been shown to improve diabetic outcomes, but current methods for monitoring blood glucose levels are painful and invasive. This trial compares traditional finger-stick glucose monitoring with the non- invasive technique of transdermal iontophoresis.
POPULATION STUDIED: A total of 92 adults with either type 1 or type 2 diabetes were enrolled from 2 diabetes centers and 3 contract research organizations. The mean age was 42 years, and 60% were women. The study population seems similar to that of a typical family practice with respect to the accuracy of noninvasive glucose monitoring.
STUDY DESIGN AND VALIDITY: The noninvasive Glucowatch biographer was compared with finger-stick capillary glucose measurements. After calibration by a single finger-stick measurement, participants wore up to 2 biographers for 12 to 15 hours while getting 2 finger-sticks per hour. Diet and insulin regimens were altered to provide a wide range of glucose levels (40-400 mg/dL).
OUTCOMES MEASURED: The major outcomes assessed were the correlation between biographer and finger-stick measures and the clinical significance of errors. Adverse effects of the biographer were also noted. Other patient-oriented outcomes, such as cost, patient satisfaction, reduction of symptoms, complications of hypoglycemia and hyperglycemia, and ease of use were not addressed.
RESULTS: Biographer readings lagged behind blood glucose measurements by a mean of 18 minutes. There was close tracking of blood glucose levels over a range of 40 to 400 mg/dL for up to 12 hours after a single calibration, and 97% of the biographer readings were associated with a finger-stick reading that was therapeutically equivalent. The average difference between measurements was 15.6%. The highest frequency of clinically significant errors was seen at blood glucose levels below 70 mg/dL; nearly one half of finger-stick measures below 70 mg/dL were read by the biographer as higher. Mild skin irritation occurred at the iontophoresis site.
Noninvasive glucose monitoring using transdermal iontophoresis can be used to track capillary glucose levels. Clinicians should understand, however, that this report is still very preliminary, and important patient-oriented outcomes have not been assessed. At a clinical level, the need for calibration, the relatively poor performance with low blood sugars, and skin irritation after 12 to 15 hours of use need further exploration. More important, this research was done by the manufacturing company on a single set of patients over a 1-day period in a laboratory environment with a suboptimal gold standard.
Although the allure of noninvasive monitoring is great, it is important to think carefully about the clinical settings in which it would be used. For patients with type 2 diabetes, the major concern has been long-term control, which may be better measured using hemoglobin A 1C every 3 months. In terms of improving clinical outcomes, there is increasing evidence that smoking cessation, low- density lipoprotein reduction, blood pressure control, and aspirin use may be much more important than blood glucose control.