Presentations by Jeremy Pettus, MD, William H. Polonsky, PhD, CDE, with commentary by Joni Beck, PharmD, CDE
Continuous glucose monitoring (CGM) has changed the lives of many people with type 1 diabetes (T1D) dramatically, so what about a role for CGM in those with type 2 diabetes (T2D)?
Two University of California San Diego experts—Jeremy Pettus, MD, associate professor of medicine, and William H. Polonsky, PhD, CDE, president of the Behavioral Diabetes Institute and associate clinical professor of psychiatry—debated whether and for which patients this treatment option might be of benefit,1 during a lively two-hour symposium at the American Diabetic Association 77th Annual Scientific Sessions in San Diego, California.
While both speakers stated that there is tremendous potential for CGM for anyone with diabetes, for argument's sake, they alternated giving pro and con arguments for three scenarios in which CGM may be considered for patients with T2D, including:
Dr. Pettus (In Favor)
Multiple studies2-4 have demonstrated that newer real-time CGM devices for patients with T1D reduced hemoglobin A1c (HbA1c) and hypoglycemia, and improved time in range as well as quality of life, said Dr. Pettus. The question for us is "Will they translate to type 2 diabetes?"
While there is potentially less variability in glucose, patients with T2D tend to be older, and some say less tech savvy, he said. He cited research from the DIAMOND study.2 "They took T2D  patients on MDI and randomized them to get SMBG or CGM and followed them for six months."
At week 24, there was an absolute HbA1c drop of 0.8%, and a relative reduction of 0.3 to 0.4%.
Dr. Pettus went through the evidence, including that no difference was found in the ease of adapting to CGM among younger versus older patients, college degree or no college degree, and other factors.
"There was a consistent HbA1c drop across all age ranges, education levels, numeracy," he said. CGM in T2D on MDI, he said, was proven to lower HbA1c and to have excellent compliance, he said.
"There was no change in insulin dose or other medications, they were taking," he said, "the HbA1c drop must be coming from lifestyle modification. People seeing it in real time makes it powerful. I think it is empowering the patient."
Dr. Polonsky (Opposed)
"It's hard to argue against the DIAMOND study outcomes," Dr. Pettus joked since he is a coauthor. Yet, he offered a counter-argument to fully explore the utility of CGM in this population.
Admittedly, there is a reasonable argument for recommending CGM in MDI users in order to reduce episodes of severe hypoglycemia, Dr. Polonsky said. However, in the DIAMOND trial, there was no impact on hypoglycemic levels, but because there were no episodes and people with it were excluded, we still need to "prove the point by studying people at risk."
The other issue, he said, is that patients in the DIAMOND study had multiple clinical contacts—seven over six months; in the real world, that is unlikely to happen for most patients.
At present, more evidence is needed in this group before we will have a satisfactory answer to its efficacy and patient demand, or more specifically, with regard to patient acceptance, he said.
Dr. Pettus (In Favor)
Dr. Pettus focused on the myths about giving CGM to those on basal insulin—that basal is well-titrated with self-monitoring of blood glucose (SMBG) alone so that patients won't be responsive to CGM results. They aren't at-risk or at low risk of hypoglycemia, he said.
"CGM can help [patients] focus not just on morning blood sugar but what is happening overnight," said Dr. Pettus.
In a study by Yoo et al,5 65 patients who were taking insulin, or insulin and oral agents, were randomized to SMBG or CGM. The result was reduced calorie intake, lost weight, and a near doubling in their exercise level. Other research shows that the HbA1c reductions persisted, even without changes in medications. "Can you imagine if that was in a pill?'' he asked.
"Not only do people do something, they keep doing [what works]" Dr. Pettus says.
Dr. Polonsky (Opposed)
Dr. Polonsky mentioned a pilot study that followed 26 older patients with T2D who were treated with basal insulin and given CGM for six months; their HbA1C decreased from 8.9 at baseline to 7.
However, Dr. Polonsky says, they received tremendous support. They could request a meeting with a CE for additional education about how to use CGM and how to make lifestyle adjustments.
"What's really the active ingredient?" he asks. Was it the CGM or the support and encouragement to make lifestyle changes?
Bottom line—We need more evidence.
"There is, as of this moment, no solid evidence of efficacy. None."
Dr. Polonsky (In Favor)
"One-third of patients had very poor glycemic control with HbA1C over 9%," Dr. Polonsky said. They often view SMBG as burdensome and don't do it as recommended. When people see their actions—attention to diet, exercise--make a positive difference, that can turn things around, he said.
"This is our opportunity with CGM," he said. CGM use among non-insulin users who have T2D will help engage patients in their own care, help them feel more confident that they can be well controlled. However, as has been said already, more evidence is needed, especially on quality of life and glycemic benefits.
Dr. Pettus (Opposed)
More than 40 T2D treatment options have been approved since 2005, said Dr. Polonksy. About half of patients achieve HbA1C under 7%, and that has not changed in the past decade. "All these new therapies are being approved…but we haven't moved the needle," he said.
The problem for this group of patients is—adherence rates, for one. Almost one-third of all diabetes prescriptions are never filled.
These patients face several obstacles, including no coverage for CGM. Until coverage expands to CGM, clinicians may want to consider adding another medication, said Dr. Pettus, rather than convincing patients to go on CGM when they can’t afford to. After HBA1C reached 8%, the average time to add a medication was over a year, according to the research, he said.
Until CGM devices get simpler and insurers cover it, time should be focused on getting patients to adhere to their current regimens. Dr. Pettus concluded.
Joni Beck, PharmD, BC-ADM, CDE, a clinical professor of pediatric diabetes and endocrinology at the University of Oklahoma in Norman, moderated the panel.
While experts may disagree on the finer points of which T2D patients should be considered for CGM, on one point there is overall agreement, she said, “the consensus is that CGM has vast potential in type 1, type 2 and even potentially for the prevention of diabetes.''
Dr. Pettus is a consultant for Dexcom and Sensionics. Dr. Polonsky is a consultant for Dexcom and Abbott Diabetes Care. Dr. Beck had no disclosures.