The US Preventive Services Task Force (USPSTF) has recommended screening for abnormal glucose as part of cardiovascular risk assessment in overweight or obese adults aged 40 to 70 years and referral of those identified with abnormal glucose to intensive behavioral interventions to promote a healthful diet and physical activity.
The recommendation, given a “B” grade for moderate evidence of benefit, was published online October 26, 2015 in Annals of Internal Medicine. The guidelines are based on the evidence for benefit or harm without consideration of cost. The document was written by the 16-member USPSTF panel, with input from public comments to a draft posted in October 2014.
The document says that screening can be performed using fasting blood glucose, HbA1c, or an oral glucose tolerance test, with follow-up intervals of 3 years for those found not to have abnormal glucose values.
For individuals found to have either impaired fasting glucose (IFG) or impaired glucose tolerance (IGT), clinicians are advised to “offer to refer…to intensive behavioral-counseling interventions to promote a healthful diet and physical activity.”
Behavioral Interventions Better Than Medications
The Task Force’s previous recommendation, from 2008, had advised screening only asymptomatic individuals with hypertension (blood pressure > 135/80 mm Hg). Since then, six new studies have shown consistent benefit of intensive lifestyle modification to prevent or delay progression to diabetes, while longer-term follow-up suggests improvement in clinical outcomes.
The lifestyle-modification part of the recommendation is the key, as the panel actually did not find direct evidence for benefit of screening per se, panel member William R Phillips, MD, an endowed professor in family medicine at the University of Washington, Seattle, said.
“We recommend screening for abnormal glucose because we see a benefit, but the benefit comes from big behavior changes, and to get these big behavior changes for the at-risk group, you need a big behavior intervention….Just doing the blood test isn’t going to get you there,” Dr Phillips said.
Indeed, the paper stipulates that such effective behavioral intervention programs — like the one implemented in the landmark National Institutes of Health Diabetes Prevention Program — “combine counseling on a healthful diet and physical activity and involve multiple contacts over extended periods.”
The panel also concluded that there is insufficient evidence that medications have the same benefits as behavioral interventions in people who have IFG or IGT but not diabetes.
“On balance, in our review of what we felt was the best evidence, we came to the conclusion that the evidence was stronger and more reliable for the behavioral intervention than for the pharmacologic intervention,” Dr Phillips said.
Other considerations for glucose screening at younger ages, according to the guideline, include people with family history of diabetes, gestational diabetes, or polycystic ovary syndrome (PCOS), and members of certain ethnic groups.
Recommendations for lipid and blood-pressure screening are mentioned, but those are covered in other USPSTF guidelines that are currently also under revision, Dr Phillips noted.
Professional Societies Respond, Find USPSTF Advice Lacking
Robert Ratner, MD, chief scientific and medical officer, American Diabetes Association, expressed concern about this latest USPSTF advice, noting that the complications of diabetes go beyond just cardiovascular disease and that the specified age range for screening may miss some people with diabetes.
“Diabetes is a serious disease that can result in dangerous, life-threatening complications, including, but not limited to, cardiovascular disease.…Diabetes is also a leading cause of blindness and amputation and is the only rising cause of end-stage kidney disease.
“Therefore, it is shocking that the USPSTF ignored the morbidity and mortality associated with diabetes itself and chose to view diabetes screening solely through a focus on cardiovascular disease risk. Diabetes screening should not just be one component of a cardiovascular disease assessment as it is in the USPSTF’s recommendation,” Dr Ratner said.
“In addition to the at-risk, minority populations that are not addressed in the new guidelines, the age bracket covered for screening does not encompass all who are at risk,” he continued.
“Diabetes screening should not be limited to ages 40 to 70. This grossly ignores the evidence of the Diabetes Prevention Program that found individuals at high risk as young as age 25 are able to reduce their risk for type 2 diabetes with lifestyle intervention.”
Moreover, “there was no upper age limit in the DPP trial, and seniors had an even higher success rate. Also of note, women with a history of gestational diabetes are at the highest risk of developing type 2 diabetes, with 50% developing type 2 diabetes within 5 years. Screening starting at 40 is not enough to combat this.”
Commenting on behalf of the American Association of Clinical Endocrinologists (AACE), Zachary T Bloomgarden, MD, clinical professor in the department of medicine, Icahn School of Medicine at Mount Sinai, New York, said that AACE supports glucose screening of people who are overweight or obese, among other risk factors.
“Diabetes prevention will delay diabetes onset and predictably result in decreased disease exposure and fewer complications. Thus, the costs of diabetes prevention can be balanced against cost savings realized from fewer patient-years of the disease, reduction in complications, and decreased need for hospitalization,” Dr Bloomgarden said.
However, he said, “We [AACE] strongly support the recommendation that lifestyle interventions be used [for IFG/IGT] but note that it is often the case that there is progression of glycemic abnormality despite attempts at diet and exercise. In such a situation, the clinician may wish to consider the use of metformin and acarbose, which have been shown to be of benefit, and may also consider thiazolidinediones and incretin-based treatments if deemed clinically reasonable.”
Dr Bloomgarden also noted that AACE disagrees about the appropriateness of HbA1c for diagnostic purposes, because of its variable relationship with blood glucose, particularly in certain ethnic groups. If used, he said, the result should be confirmed with blood glucose measurements.
And with regard to the 3-year screening interval, he said “We would point out that if an abnormal glucose level is detected or if the risk factor changes for the worse — for example, with substantial weight gain — the screening interval should be shortened to less than 3 years, at the discretion of the treating physician.“
Indeed, Dr Phillips noted that the panel found very little evidence to inform an interval recommendation. “There are no studies of quality that tell us that one interval is better than another. We felt 3 years is a reasonable choice, but it is a subjective choice largely. Other people might pick other intervals.”
The American Academy of Family Physicians, which typically follows USPSTF guidelines, provided with this statement: “Once the USPSTF’s recommendation is released to the public, the AAFP’s subcommittee on Preventive Services will review the recommendation and its supporting evidence to determine whether the AAFP agrees with the recommendation.”
“How Am I Going to Provide This to My Patients in Large Numbers?”
Dr Phillips said that while the questions related to the screening process itself are “worthwhile debates,” the behavioral interventions for people who are found to have IFG or IGT is the more important message from this document, because it is aimed at spurring major changes in healthcare delivery.
“The real important emphasis is when healthcare providers find patients with these risk factors, how do they respond and how do they create in their practices or healthcare systems the resources that are needed to help patients achieve these changes? They’re not simple.…We hope that our recommendations will encourage doctors and practices to develop and find how to get these services to patients in the community.”
The document includes a link to the page of the Community Preventive Services Task Force, which outlines the evidence base for behavioral interventions for people at risk for type 2 diabetes and the specific components of the programs found effective in clinical trials.
Although the panel specifically did not address cost and does not make insurance coverage decisions, the Affordable Care Act does mandate that insurers cover services recommended as grade “A” or “B” by the USPSTF, Dr Phillips noted.
He said that “when physicians and other care providers read this document and accept that this is a B recommendation with moderate evidence and modest benefit, their response should be the question, ‘How am I going to provide this to my patients in large numbers?’ Then it’s their obligation to figure out how to do that. That is one of the most substantial impacts of publishing this document.”
As a member of the USPSTF, Dr Phillips has no relevant financial relationships. Dr Bloomgarden receives consulting fees/serves on advisory boards for AstraZeneca, Janssen, Novo Nordisk, Merck, Amgen, and Novartis; receives speaking fees for non-CME/CE services from AstraZeneca, Janssen, Novo Nordisk, and Merck; and has ownership interest in Baxter International, CVS Caremark, Roche Holdings, St Jude Medical, and Novartis.
Ann Intern Med. Published online October 26, 2015. Abstract