Three Experts Weigh In On CGM

Support for technology grows; more calls for artificial pancreas


By Kelly Close,Close Concerns

Continuous glucose monitoring was the focus of several sessions at AACE, but we were particularly interested in one on Friday, April 13, sponsored by AACE, the Juvenile Diabetes Research Foundation, and Abbott Diabetes Care. In a departure from years past, the JDRF is making a strong push – in dollars and publicity – for CGM; we've attended no fewer than five conferences this year in which the JDRF, given the opportunity to promote any of its research initiatives, has focused on CGM as an effective therapy in itself and as a pathway to reaching the artificial pancreas.

We support the JDRF's initiative, and we have high regard for the JDRF lead spokesman on the matter, Dr. Aaron Kowalski. A person with type 1 diabetes who wears a continuous sensor (he started his presentation at 118 mg/dL or 6.55 mmol/l), he oversees the JDRF Artificial Pancreas Project and was one of three speakers at this AACE event.

Joining Dr. Kowalski was Dr. Daniel Einhorn, Diabetes and Endocrine Associates Medical Director at Scripps Whittier Institute for Diabetes, and Dr. Lois Jovanovic, CEO and Chief Scientific Officer at the Sansum Diabetes Research Institute.

Dr. Daniel Einhorn
While some presenters focus almost exclusively on the advantages of the CGM, Dr. Einhorn presented a very balanced picture – one based, he said, on feedback from his own patients. He identified the clear benefits ("trends reveal secrets," "alarms," "safety," etc.) and he also laid out the challenges. The sensor can fail outright, can be inaccurate, can take time to "acclimate," can "wane," and can be unreliable at extreme highs and lows. Managing the data is also a very complex undertaking for both patient and clinician.

A typical response from patients, he said, is this: "It's some of the most difficult, frustrating technology I've ever had and I don't know how I ever lived without it."

Reimbursement remains a challenge. Dr. Einhorn asked how many audience members had patients who were reimbursed for CGM, and several hands went up. Dr. Einhorn seemed cautiously optimistic that insurers, if given the right information, would come around. "I think there's a soft spot for this," he said. We're hearing more and more sentiments like this, which are coming as a happy surprise from our perspective, given the power of managed care in recent years.

Dr. Einhorn reiterated that the technology is time consuming for office personnel, but also said (from our perspective, this was positive to hear) that training patients on insulin pumps takes far more time – that was a positive in our perspective since to us, it suggested health care providers would likely be more positive on this topic than in years past. Some of his patients wear sensors for 15 days – that's longer than we typically hear! – and some of his patients take breaks from the sensors: a weekend off, for example, which sounds reasonable to us. From our discussions with patients, CGM use helps with two important things – both refining basal rates if the person is on a pump, as well as hour-to-hour corrections. If reliability is an issue, that's what prompts people to take breaks.

Dr. Einhorn also emphasized the challenges of predicting future glucose trends. Lag times exist, for example, in sensor and meter readings, and absorption varies in subcutaneous insulin. "Even with trend data, you don't know what's going to happen next," he said. "It does not substitute for thinking." We agree, though we note at their best, sensors do help patients figure out the future more than a traditional monitor can.

And while patient selection is key, Dr. Einhorn acknowledged that's difficult. "I have not been able to predict which of my patients will hate it or love it," he said. "Some love it, some throw it in your face."

Dr. Aaron Kowalski
While the ADA and AACE have identified A1c goals – less than 7 percent and 6.5 percent, respectively – the JDRF believes those are not good enough. "We need true eugylcemia, but we can't do it with single-point testing," Dr. Kowalski said. Hurrah! We also agree on this front that a strive to normalcy (similar to goals for blood pressure and cholesterol) make sense and that we should be building, approving, and paying for tools that help us reach normalcy.

The biggest and long-discussed hurdle, of course, is hypoglycemia – the tighter the control, the greater the incidence of lows – and Dr. Kowalski showed a slide of a low, flat-lining blood sugar from a patient who was wearing a sensor and ultimately had a seizure. "This sums up why we need continuous glucose monitoring," he said. "It's appalling that people are going into seizures." It's also the case, he said, that as shown in an excellent study led last year by Dr. Bruce Bode, even with nine finger sticks a day, patients spend less than 30 percent of the day between 90 and 130 mg/dL (5 and 7.22 mmol/l).

The JDRF has two areas of emphasis with this technology: a large randomized continuous glucose sensor trial, and a multi-center approach to "close the loop." Its goals are to develop the data needed for reimbursement and ultimately to create an artificial pancreas. For the former, it's selected 10 sites in the U.S. (health clinics and managed care plans) for a randomized control trial comparing outcomes of type 1 patients using CGM compared to those using traditional meters. (Patients include adults and children, ages 8 and older.)

Meanwhile, research at the JDRF Yale Hypoglycemia Center has demonstrated "Artificial Pancreas Closed-loop feasibility with ‘off-the-shelf' technologies." Dr. Kowalski showed blood-glucose data from both the "closed loop" and "hybrid-closed loop" trials. The closed-loop operates without any patient interaction, showing that "it is possible," though it's all done in clinic right now. The hybrid loop actually produced better results (mean glucose of 135 mg/dL – 7.5 mmol/l – for hybrid versus 156 mg/dL, or 8.66 mmol/l, for full). In the hybrid system, the children gave a "mini-bolus" before each meal, but otherwise the closed-loop algorithm controls the pump. This underscores the main limitation of the closed-loop right now: even with "rapid-acting insulin," it's not rapid enough when delivered subcutaneously. We will be watching closely for how VIAject emerges (Biodel, which makes what we're cautiously referring to as VRAI – very rapid acting insulin – had its IPO late last week – it closed the week well, up 20%, at $18/share, after pricing at $15, between its $14-16 range.)

Dr. Lois Jovanovic
Dr. Jovanovic began her remarks by emphasizing the burden of complications – both physical and financial – and concluded, "To get rid of complications A1c's need to be under 6 percent." She noted that the ADA believes glycemic control is a balance of three factors represented by a triangle: exercise, diet, and insulin. But she believes the appropriate figure is really a square: exercise, diet, insulin, and stress. The latter comes in three forms (psychological, physical, and hormonal), can be mild, moderate, or severe, and can cause chaos with glycemic control.

All of which has a big impact on insulin needs, but some of these problems can be addressed by the flexibility of an insulin pump and frequent blood testing.

But what we really need are artificial pancreatic beta cells, and Dr. Jovanovic described our progress in this area. We now have minimally invasive glucose sensors (she showed both the MiniMed CGMS and the DexCom STS CGMS), which can detect how long each day a patient is hyperglycemic. One study showed that the DexCom 7-day sensor was stable over all seven days, and another study showed that the CGM increased the time spent in normal glucose range by 26 percent.

Dr. Jovanovic then discussed the importance of combining algorithms with medical expertise to achieve good control; with CGM, she believes we can eliminate the guesswork in diabetes care, and she showed a slide of a patient strapped to a machine – delivering either insulin or glucose – that produced a flat-line blood sugar graph. Dr. Jovanovic believes that's the direction we're headed. "It's not the art of medicine," she said. "It's all science."

Kelly Close is Editor-in-Chief of diaTribe , an electronic newsletter that helps people learn about new ways to manage diabetes better. diaTribe focuses on new drugs, devices and research. diaTribe is free and available online at

NOTE: The information is not intended to be a replacement or substitute for consultation with a qualified medical professional or for professional medical advice related to diabetes or another medical condition. Please contact your physician or medical professional with any questions and concerns about your medical condition.

Last Modified Date: November 08, 2013

All content on is created and reviewed in compliance with our editorial policy.

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