Docs' Beliefs Guide Prescribing of Glucose Monitoring in Type 2 Diabetes

Miriam E. Tucker

July 31, 2018

When it comes to prescribing routine self-monitoring of blood glucose (SMBG) in patients with type 2 diabetes who aren't treated with insulin, physicians' prescribing is often based on belief rather than evidence, new qualitative data suggest. 

Results from the study, which involved semi-structured interviews with 17 full-time Ohio primary care physicians, were published in the July/August issue of Annals of Family Medicine by Sonia Havele, a medical student at Cleveland Clinic, Ohio, and colleagues. 

Overall, 14 of the 17 physicians said they prescribe routine SMBG to patients with noninsulin-treated type 2 diabetes, although six were "limited proponents," in that they support routine blood glucose checks for certain situations, such as newly diagnosed patients or those with HbA1c levels that are too high. 

Among medical societies, there is general agreement that SMBG is beneficial for all patients with type 1 diabetes and for those with type 2 diabetes who take insulin.

But for patients who do not take insulin, the preponderance of evidence suggests that SMBG doesn't help lower HbA1c, Havele told Medscape Medical News in an interview.

"Currently, there are a lot of opportunities in healthcare to cut back on costs without doing any harm to patients, and I think this is a really great example of that," she said.

"A Breadth in How People Practice"

Several themes emerged from the interviews.

Some physicians viewed SMBG as an opportunity for education to promote lifestyle changes, particularly at the time of diabetes diagnosis, but opponents feel in-office education around HbA1c results suffice for that purpose and that SMBG doesn't have a direct impact.

All participants agreed that HbA1c surpasses SMBG as a basis for making treatment decisions, and both SMBG proponents and opponents cited the cost of test strips as barriers to the practice.

There was general agreement that patients at risk for hypoglycemia should perform SMBG. (The survey inquired about patients not taking insulin, but didn't specifically address the issue of sulfonylureas, which carry a high risk of hypoglycemia, as opposed to other medications.)

And most also agreed that certain patients — such as those with low health literacy or physical or cognitive impairment — might not be good SMBG candidates. 

Several of the surveyed physicians noted that they prescribe routine SMBG less often than they did 10 years ago, when their professional societies were encouraging the practice.

"There's more awareness now," Havele said, but also noted that "there are doctors who still believe it's an effective way to promote self-efficacy or education...Our main finding was that there was a breadth in how people practice and what people believe about SMBG."

What Do the Guidelines Say?

In the article's introduction, Havele and colleagues point to the Choosing Wisely campaign by the American Board of Internal Medicine Foundation, to which professional societies contribute lists of medical practices that "providers and patients should question."

Among those, the Society of General Internal Medicine (SGIM) included "Don’t recommend daily home finger glucose testing in patients with type 2 diabetes mellitus not using insulin."

The SGIM text adds that "daily finger-glucose testing has no benefit in patients with type 2 diabetes mellitus who are not on insulin or medications associated with hypoglycemia, and small, but significant, patient harms are associated with daily glucose testing. SMBG should be reserved for patients during the titration of their medication doses or during periods of changes in patients' diet and exercise routines."

Havele and colleagues write that this contrasts somewhat with recommendations from the American Diabetes Association (ADA), which state in part, "When prescribed as part of a broad educational program, SMBG may help to guide treatment decisions and/or self-management for patients taking less frequent insulin injections or noninsulin therapies."

The "less frequent injections" recommendation is based on B level evidence, and the noninsulin therapies, E level evidence.

The ADA Standards of Care 2018 further qualifies its advice, stating "a key consideration is that performing SMBG alone does not lower blood glucose levels. To be useful, the information must be integrated into clinical and self-management plans."

The ADA recommendation is nuanced and intended to leave options open for patient-centered care, ADA science and medicine president Jane Reusch, MD, told Medscape Medical News, noting that meta-analysis data actually suggest that SMBG in insulin-naive patients can reduce HbA1c by 0.25–0.3 percentage points at 6 months, although the effect tends to wane by 1 year.  

"I would take issue with the [Havele paper's] opening statement that ADA recommends daily glucose testing in everyone," said Reusch, who is professor of medicine, biochemistry, and bioengineering at the University of Colorado Anschutz Medical Campus, Denver.

"If I have a person with beautifully controlled diabetes, I probably would not recommend that they test their blood glucose all the time unless something was changing," she explained.

However, she acknowledged that although the ADA guidelines are meant to enable individualized care, they could be misinterpreted.

"There's always a balance in the guidelines between being too proscriptive and being so general that the person trying to help carry out the guideline with the patient doesn't really know what's being said."

Reusch, who has not served on the ADA Standards writing committee thus far, also noted that the annually updated document might be more helpful if it included examples of situations in which routine SMBG might be particularly useful.

For example, these might include time of diagnosis, when a patient starts a new lifestyle change such as a weight-loss program, or when they have trouble achieving their HbA1c target.

Or, for patients who want to do testing, options might include intermittent fasting and post-meal checks.

Reusch said she intends to raise the issue with the ADA Standards writing committee for consideration for 2019.

Havele said her team's next step will be to assess patients' perspectives of SMBG.

"Our study addresses the physician perspective but there's also the patient perspective...We don't have a clear understanding of how much they want to do this and how much they believe it does or doesn't help them. That's an area of interest for me personally, and I think that will be valuable in terms of understanding the issue."

Reusch is a consultant for Oramed and has received research funding from Merck. Havele has reported no relevant financial relationships.

Ann Fam Med. 2018;16:349-352. Full text

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