Medical Device Daily Executive Editor

SAN DIEGO – A variety of posters on glucose monitoring and sensing were featured during this week’s annual scientific sessions of the American Diabetes Association (ADA; Alexandria, Virginia).

One poster featured research into use of continuous glucose monitoring in detecting hypoglycemic episodes. The study followed 24 Type 1 diabetic patients on insulin pump therapy.

Tissue glucose was measured with a continuous glucose monitoring system from Medtronic MiniMed (Northridge, California), using sensors from Roche Diagnostics (Indianapolis). Venous (blood) glucose was measured at least hourly by an Accu-Chek Compact system. During hypoglycemic (low blood sugar) episodes, blood glucose was measured twice, with mean venous readings compared with mean tissue readings.

The research showed that tissue glucose monitoring is “comparable” to venous blood glucose measurements in hypoglycemic situations.

The researchers did note that in some cases, higher tissue glucose values might be observed, and said further studies should be conducted in order to evaluate whether higher warning levels are necessary on continuous glucose monitoring systems in order to adequately detect hypoglycermic episodes.

Another poster described an analysis of the effectiveness of alerts in the Guardian continuous glucose monitoring system from Medtronic MiniMed. A total of 71 persons were followed, randomly divided into control and alert groups. Hypoglycemia and hyperglycemia alerts were set at 70 mg/dl and 250 mg/dl, respectively.

Researcher Lu Wang’s study indicated that, when fingerstick glucose measurements were taken, the Guardian system confirmed that blood glucose readings were within acceptable range 87% of the time.

The system identified five hours per day of glycemic risk among the Type 1 patients in the study and also detected 2.5 times as many nighttime hypoglycemia episodes than use of a conventional meter alone.

The patients with the Guardian alarm turned on took one additional meter glucose reading in the hyperglycemic or hypoglycemic ranges per day.

Wang said the alarm feature “provides valuable guidance for patients to take meter glucose readings. By properly adjusting the alarm threshold, the risk of missing an acute hypoglycemia or hyperglycemia can be greatly reduced, [although] at the cost of more false alarms.”

Another poster reported on a study of maintaining effective glucose control using the OneTouch UltraSmart System from LifeScan (Milpitas, California), a Johnson & Johnson (New Brunswick, New Jersey) company. The UltraSmart System is an integrated glucose meter and electronic logbook.

The study, which involved comparison with conventional glucose meters and paper logbooks, showed a greater reduction in A1c (a test that determines average blood glucose over a two- to three-month period) levels by those in the OneTouch UltraSmart arm, although both the test and control groups showed improvements in those readings.

Self-monitoring of blood glucose increased over the 16 weeks of the study in the UltraSmart group, and researchers said the “significant lowering” of A1c readings in the test group may have been accounted for by that increase, along with the “enhanced pattern recognition and record-keeping” made possible with the electronic logbook feature.

Another poster cited increased frequency of self-monitoring as being responsible for improved A1c readings in non-insulin users. The researchers noted that with insulin-taking patients, a high blood glucose reading “is the cue for the patient to take insulin,” but that for non-insulin-taking patients, “there is no similar recourse.” This, they said, “would lead one to believe that the effect, if any, would be smaller for non-insulin users.”

They studied the records of 522 non-insulin-treated patients, with the data indicating that in fact, “there is a pathway whereby the patient’s frequent use of a meter contributes to control even though no insulin is taken.”

Separately, an ADA symposium featured research on diabetes’ effects on the vascular system.

Rama Natarajan, Phd, professor in the department of diabetes at Beckman Research Institute of the City of Hope (Duarte, California), cited the “significant increases in cardiovascular disease [CVD]” impacted by the complications associated with diabetes.

Reporting on research examining vascular dysfunction caused by diabetic complications that inhibit the thickening of artery walls, she said: “it’s very important to study the underlying mechanisms” of obesity, diabetes and CVD.

During a lecture on “Development of the Metabolic Syndrome in Type 1 Diabetes,” John Brunnell, MD, professor of medicine at the University of Washington (Seattle), said that nearly one-quarter of the U.S. population has metabolic syndrome, which, along with hyperlipidemia, “are major contributors to diabetes and are associated with premature coronary disease.”

Citing such factors as genetics-based weight gains, he said that “intensive” diabetic therapy can have a ‘profound” effect on weight control. Noting that obesity “is at the heart of these problems,” he said that exercise is the key to the lifestyle changes that are central to treatment.

Also during the symposium:

• Vincent Hascall, PhD, professor of biology at the Cleveland Clinic Foundation and Case Western Reserve University (both Cleveland), described molecular and cellular events that affect the CD44 membrane, marking the beginning of diabetic nephropathy.

• Christopher Glass, MD, PhD, professor of medicine at the University of California-San Diego, discussed peroxisome proliferator-activated receptors, saying that PPAR “is primarily a negative regulator of macrophage gene expression. The macrophage may be a signal target of insulin sensitivity.”