Diabetes and PAD: Risk Management, Treatment Options
PHILADELPHIA—Diabetes is a major risk factor for peripheral artery disease (PAD), said Mary McDermott, MD, professor of medicine at Northwestern University’s Feinberg School of Medicine, during her talk at the American Heart Association (AHA) 2019 Scientific Sessions.
PAD often presents differently in patients with diabetes compared with those without diabetes, Dr McDermott said. Compared with their counterparts without diabetes, patients with PAD and diabetes are often younger, present with more atypical leg symptoms and asymptomatic disease, have more distal atherosclerosis, have poorer lower extremity functioning, have a higher risk of critical limb ischemia, and have a higher rate of major adverse cardiovascular events (MACE), she explained.
Although PAD is typically diagnosed using the ankle-brachial index (ABI), this method can be problematic in patients with diabetes, especially when measuring the progression of disease. An ABI of 0.9 is only about 63% sensitive in patients with diabetes, Dr McDermott explained. Performing a toe-brachial index may be useful in patients with diabetes and PAD without a low ABI, she said.
PAD is known to be associated with functional decline over time, and the presence of comorbid diabetes is associated with increased risk of major lower extremity amputations or limb events. PAD patients with diabetes also tend to have more distal and multilevel disease compared with those without diabetes. Patients with these conditions are less likely to be candidates for lower extremity endovascular procedures because they often do not respond as well to endovascular procedures compared with patients with PAD without diabetes, thus limiting therapeutic options for this patient population, Dr McDermott said.
It is important for patients with PAD and diabetes to be treated with intensive atherosclerotic disease risk factor therapy due to their high MACE risk. Pharmacologic regimens should include statins (especially a high-dose potent statin), anti-platelet therapy like clopidogrel or aspirin, and an angiotensin-converting enzyme inhibitor or angiotensin II receptor blocker such as Ramipril or telmisartan, respectively. Smoking cessation is also key in this patient population, she added.
When it comes to managing diabetes in PAD, a hemoglobin A1c of less than 7.0% is “a reasonable target,” Dr McDermott said. In this patient population, she noted, the use of the sodium-glucose co-transporter 2 (SGLT2) inhibitor canagliflozin should probably be avoided due to a small but increased risk for peripheral amputations, which was evidenced in the CANVAS trial.
However, this observation “does not seem to be a class effect,” Dr McDermott noted. “In other trials of SGLT2 inhibitors like the CREDENCE trial, there does not seem to be this association, but the jury may still be out,” she said.
Currently, the most effective medical therapy for walking impairment in this patient population is supervised exercise, as stated in the 2016 guidelines from the AHA and American College of Cardiology, said Dr McDermott. Cilostazol and pentoxifylline are the only FDA-approved medications for walking impairment in PAD, but neither works particularly well, she noted.
Home-based walking exercise may also be a viable option in certain cases, said Dr McDermott. Although a 2018 trial found that a home-based exercise intervention with a wearable activity monitor and telephone counseling was not associated with improved walking performance compared with usual care, home-based walking exercise should not necessarily be ruled out, especially if a patient does not have access to a supervised exercise program, she said.
Dr McDermott concluded her talk with several key takeaways, including:
- Patients with PAD with diabetes have more adverse lower extremity outcomes than PAD patients without diabetes.
- Patients with PAD and diabetes should be treated with intensive atherosclerotic disease risk factor therapy.
- Supervised exercise programs are associated with improved walking performance in patients with PAD. For patients who do not have access to these programs, home-based exercise may be considered.
McDermott MM. Diabetes and peripheral arterial disease. Presented at: American Heart Association 2019 Scientific Sessions; November 16-18, 2019; Philadelphia, PA.