Is self-monitoring of blood glucose still needed for diabetes?
Self-monitoring of blood glucose could become more of a targeted therapy than a blanket approach, with individual factors determining its value, experts say.
It has long been considered a staple of diabetes care. Recently, though, debate over self-monitoring of blood glucose (SMBG) has become more pointed, with new research casting doubt on its effectiveness for patients with type 2 diabetes.
The study, published in June by JAMA Internal Medicine, found no significant differences in glycemic control, health-related quality of life, or adverse events between non-insulin-dependent type 2 diabetes patients who used SMBG and those who did not.
“These results suggest that we can safely advise patients to discontinue, as well as not initiate, SMBG,” wrote Elaine C. Khoong, MD, and Joseph S. Ross, MD, ACP Member, of the University of California, San Francisco, and Yale University schools of medicine, respectively, in an accompanying editorial. “The surprising findings make us question the current seemingly common sense-based strategy to encourage routine SMBG … Routine SMBG merits a ‘less is more’ designation because there were no clear benefits accrued, which leaves only possible harms.”
Does this mean SMBG's days are numbered? It depends on whom you ask and whom you're treating. Experts say SMBG could become more of a targeted therapy than a blanket approach, with individual factors determining its value.
Another consideration may be patient preference. Only 41% of participants in the JAMA Internal Medicine study expressed a preference for SMBG, while 22% preferred to avoid it. According to a study published in June by the journal mHealth, only 57.6% of patients with type 2 diabetes adhered to SMBG recommendations from their physicians.
That may not be surprising, given the nature of the test—pricking one's finger or other body part for blood, sometimes several times a day.
“Look at the individual patient and how we want them to do [the test],” said Avantika Waring, MD, an endocrinologist and medical director of the diabetes program at Kaiser Permanente Washington in Seattle. “It's a thing that, frankly, can be quite onerous.”
When it works, or doesn't
Of course, onerous as it may be, SMBG is not up for debate among certain categories of diabetes patients.
“A distinction needs to be made between patients with either type 1 diabetes or type 2 diabetes who use multiple daily injections of insulin or an insulin pump, and patients with type 2 diabetes not using insulin,” said Roy Beck, MD, PhD, executive director of the Jaeb Center for Health Research in Tampa, Fla. “For the insulin users who receive boluses of insulin at mealtime, glucose monitoring is critical and the frequency of blood glucose monitoring has been shown to be strongly associated with the level of glycemic control.”
The question is whether and when the process is worthwhile for patients with relatively uncomplicated type 2 diabetes.
On the other hand, the costs of purchasing an SMBG monitor and testing strips can be a nuisance or an outright dealbreaker. A 2012 study in the Journal of Managed Care and Specialty Pharmacy revealed that SMBG supplies run an average of $772 per year for a patient who regularly monitors his or her blood glucose.
However, several studies have shown SMBG can sometimes save money both for patients and the wider delivery system by helping to reduce complications and inpatient stays. But that is only the case when SMBG is actually needed and carried out as recommended. Those two dynamics are at the heart of the current SMBG debate.
Improving patient interactions
Patient adherence is an ongoing challenge across the health care system. In the case of SMBG, there does not appear to be a clear demographic predictor, such as socioeconomic status or education level, for adherence. Rather, the issue appears to manifest itself more or less across the board.
Making sure patients fully understand SMBG and can interpret the data themselves is a start toward a solution, physicians said. A slight shift in physician attitude toward the patient and the data, and a little more time spent up front on communication, can pay dividends down the line.
“Do we all have perfect patients? The answer is no,” said David O’Dell, MD, FACP, LeeRoy Meyer Professor of Medicine at the University of Nebraska Medical Center in Omaha. “Become a coach instead of a judge.”
Furthermore, if physicians order monitoring, they should take time to review the data gathered with the patient, experts recommend.
“The biggest thing I hear is physicians don't look at the data,” said Irl B. Hirsch, MD, MACP, an internist and endocrinologist and the diabetes treatment and teaching chair at the University of Washington School of Medicine in Seattle. “Software allows you to download it, but the big thing is doctors are only interested in HbA1c, not the rest of the data. If doctors don't want to use it, patients don't want to do it.”
“Patients enjoy getting that feedback and looking at the work they've been doing,” said James Chamberlain, MD, an internist and medical director for diabetes services at St. Mark's Hospital in Salt Lake City.
Although the SMBG process can be time-consuming, particularly during a routine 15-minute visit, it can be arranged to maximize efficiency.
“If a patient is frustrated [with self-monitoring], the number-one thing is physicians spend the time and review the data with them,” Dr. Hirsch said. “It does not need to be three months of data, but maybe the last three days.”
Another issue that crosses socioeconomic boundaries, particularly among patients with diabetes, is depression. Depression is more common among those with diabetes than it is in the general population, and it can reduce the likelihood that a patient will take necessary steps, including SMBG, to manage or improve their condition.
According to a 2008 analysis, 31% of diabetes patients displayed depressive symptoms, with 11% meeting the criteria for major depressive disorder. In controlled studies, people with diabetes were twice as likely to suffer from depression as those who did not have diabetes.
What's more, patients with both diabetes and another medical comorbidity, including diabetes, are three times more likely to be nonadherent to their care plans. In diabetes, this includes SMBG.
“When people get depressed,” Dr. Chamberlain said, “we try to talk to them about that.”
According to the 2008 analysis, the treatment of depression in patients with diabetes can usually be coordinated in a primary care setting. The familiar tools that are used to treat depression in patients without diabetes—diagnostic screenings, psychotherapy, and medication—also are effective in those with diabetes. However, monoamine oxidase inhibitors and tricyclic and tetracyclic antidepressants are not recommended because of potential adverse effects related to weight gain, cardiac conduction, and postural hypotension.
Although the new study findings indicate that SMBG does not necessarily help people with noninsulin-dependent type 2 diabetes, there is not yet—and may never be—clear recommendations, or even a clear consensus, on which patients should or should not be conducting SMBG.
According to experts, there is no specific group of diabetes patients that is necessarily “ineligible” for SMBG, although it is possible that some patients could safely discontinue the practice if their HbA1c, blood glucose levels, and/or other metrics are in a consistently desirable range.
“It could be that a patient is nonadherent because they are eating right and exercising and their data never changes,” Dr. Chamberlain said.
For now, SMBG opinions vary widely, and it appears that SMBG could be considered on a case-by-case basis, rather than as a default component of any diabetes management plan.
However, Dr. Chamberlain recommends performing SMBG as part of uncomplicated type 2 diabetes treatment at the outset of every case, then re-evaluating based on how well the patient is doing with managing the condition and adhering to SMBG itself. No patient can be forced to adhere to SMBG or any aspect of a care plan, but starting the plan with SMBG can introduce patients to the practice and its potential effectiveness, he said.
“Noninsulin users can benefit [from SMBG] at the beginning of the disease because they can learn a lot about the role of nutrition,” Dr. Chamberlain noted. “I don't think anyone will stop doing that.”
A new wave of technology is still making its way, slowly but surely, to the doctor's office and could bring major change for the practice of SMBG and diabetes care itself.
Continuous glucose monitoring, or CGM, which provides more, and more current, data, may be the most prominent example. A 2013 systematic review published in Diabetology and Metabolic Syndrome found that CGM outperformed SMBG in lowering HbA1c in adults with type 2 diabetes.
CGM does not necessarily replace SMBG in all cases, but experts seem bullish on its future.
“I believe that in the future CGM will become universal for insulin users and more frequent for noninsulin type 2 diabetes as sensors become smaller, don't require a fingerstick to calibrate, and are disposable,” Dr. Beck said. “More and more patients are using a continuous glucose monitor in addition to or instead of a blood glucose monitor.”
CGM devices can also work remotely, with different parties having the ability to access data and receive alerts.
“Say it's three o’clock in the morning, and Grandma's blood glucose levels go below 60. You can be 300 miles away and see it on your phone,” Dr. Hirsch said. “Other people can watch one person's glucose levels for hypo- and even hyperglycemia.”
Meanwhile, new CGM devices, such as the Abbott Freestyle Libre Pro, which was approved last fall by the U.S. Food and Drug Administration for use by clinicians, are in the pipeline. The FDA is currently reviewing a consumer version of the product.
In the meantime, while new technology develops, most physicians and patients continue to use SMBG.
“It is what we have and it's very helpful. Before this, people were out at sea trying to figure out their own sugars,” Dr. O’Dell said. “For type 1 and type 2 patients on complicated insulin regimens, SMBG is essential. In a subset of patients, CGM may be part of the answer, but at this point we do not have the data to recommend it for the majority of patients. That leaves us with SMBG.”
As long as SMBG remains the dominant tool of its kind, debate seems likely to continue over when to use it, how to use it, or whether to use it at all.
“We're undergoing tremendous transformation in self-monitoring of blood glucose. Glucose monitoring as we know it is completely changing,” Dr. Hirsch said. “When you look at [SMBG for] type 2 diabetes data for people not on insulin, the outcomes are at best equal. It shows maybe we can question how much the glucose data is helpful.”