The side effects
While others praised these drugs for their beneficial effects, they also noted that the side effects of these drugs are serious and must be discussed with patients.
GLP-1 receptor agonists are linked to gastrointestinal symptoms, especially nausea, while SGLT2 inhibitors have been linked to kidney failure, ketoacidosis, and more. The Food and Drug Administration warned in 2018 that the SGLT2 inhibitors can cause a rare serious infection known as Fournier’s gangrene – necrotizing fasciitis of the perineum.
“We have to tell our patients to let us know right away if they get pain or swelling in the genital area,” Dr. Paauw, who is on the Internal Medicine News board, noted. “The chance that an infection could explode quickly is higher in those who take these drugs.”
Amputation risks also are associated with taking the SGLT2 inhibitor canagliflozin (Invokana). The FDA requires the manufacturer of this drug to include a black-box warning about the risk of “lower-limb amputations, most frequently of the toe and midfoot,” but also the leg. In approval trials, the risk doubled versus placebo.
These amputation risks “put a damper on some of the enthusiasm on behalf of physicians and patients ... for taking this drug,” noted Dr. Roberts, who is a professor of internal medicine at the University of Central Florida, Orlando.
While a manufacturer-funded study released last year found no link to amputations, the results weren’t powerful enough to rule out a moderately increased risk.
Dr. John B. Buse
“[If] you are at high risk for having an amputation, we really have to take this risk very seriously,” said John B. Buse, MD, chief of the division of endocrinology at the University of North Carolina at Chapel Hill, in a presentation about the study at the 2018 annual scientific sessions of the American Diabetes Association.
The benefits
Despite these risks of adverse events, most interviewed agreed that the many benefits observed in those taking SGLT2 inhibitors or GLP-1 receptor agonists make them worth prescribing, at least to those who are able to afford them.
Both SGLT2 inhibitors and GLP-1 receptor agonists appear to have significant cardiovascular benefits. A 2019 meta-analysis and systematic review found that both drugs reduced major adverse cardiac events by about 12% (Circulation. 2019 Apr 23;139[17]:2022-31).
Dr. Douglas S. Paauw
“They don’t cause hypoglycemia, they lower blood pressure, they don’t cause weight gain, and they might promote weight loss,” noted Dr. Paauw.
SGLT2 inhibitors also have shown signs of kidney benefits. The CREDENCE trial linked canagliflozin to a lowering of kidney disorders versus placebo (N Engl J Med. 2019 Jun 13;380[24]:2295-306). “The relative risk of the renal-specific composite of end-stage kidney disease, a doubling of the creatinine level, or death from renal causes was lower by 34% (hazard ratio, 0.66; 95% confidence interval, 0.53-0.81; P less than .001), and the relative risk of end-stage kidney disease was lower by 32% (HR, 0.68; 95% CI, 0.54-0.86; P = .002),” the trial investigators wrote.
“They showed very nicely that the drug improved the kidney function of those patients and reduced the kidney deterioration,” said Yehuda Handelsman, MD, an endocrinologist in Tarzana, Calif., who chaired the 2011 and 2015 American Association of Clinical Endocrinologists’ Comprehensive Diabetes Guidelines. The study was especially impressive, he added, because it included patients with low kidney function.
SGLT2 inhibitors’ “diuretic mechanism explains why there is a substantial reduction in heart failure hospitalizations in patients who take these drugs,” said cardiologist Marc E. Goldschmidt, MD, director of the Heart Success Program at Atlantic Health System’s Morristown (N.J.) Medical Center, in an interview. “Both the EMPA-REG Outcome and the CREDENCE trials demonstrated substantial benefit of this class of medications by showing a lower risk of cardiovascular death as well as death from any cause and a lower risk of hospitalization for heart failure."
Overall, the SGLT2 trial data have been very consistent with a benefit for cardiovascular risk reduction, particularly in regard to heart failure hospitalizations and even in potentially preventing heart failure in diabetics,” he added.
Dr. Skolnik, a columnist for Family Practice News, cited SGLT2 inhibitors and GLP-1 receptor agonists’ ability to slow renal disease progression, promote weight loss, and prevent poor cardiac outcomes.“These drugs should be used, in addition to metformin, in all patients with diabetes and vascular disease. These proven outcomes are far better than we ever were able to achieve previously and the strength of the evidence at this point is very strong,” said Dr. Skolnik. “In addition to the benefits of decreasing the development of cardiovascular disease, serious heart failure, and slowing progression of renal disease, these two classes of medication have additional benefits. Both classes help patients lose weight, which is very different from what was found with either sulfonylureas or insulin, which cause patients to gain weight. Also both the SGLT2 inhibitors and the GLP-1 RAs [receptor agonists] have a low incidence of hypoglycemia. For all these reasons, these have become important medications for us to use in primary care.”
Other recent trials offer “very powerful data” about SGLT2 inhibitors, Dr. Roberts said. That’s good news, since “our approach needs to be toward cardiovascular protection and preservation as well as managing blood sugar.”An Israeli trial, whose results were released in May 2019 at the annual meeting of the American College of Cardiology, found that, compared with other glucose-lowering drugs, taking an SGLT2 inhibitor was associated with lower risks of heart failure hospitalization and all-cause mortality (HR, 0.54; 95% CI, 0.44-0.65; P less than .001). This trial also offered a new detail: The patients gained the benefit regardless of whether their baseline left ventricular ejection fraction was preserved or reduced (J Coll Cardiol. 2019 Mar;73[9]:suppl 1). The SGLT2 inhibitors used in this trial included dapagliflozin (Farxiga) and empagliflozin (Jardiance).
In another study released this year, a subanalysis of the DECLARE-TIMI 58 trial, researchers reported that the SGLT2 inhibitor dapagliflozin reduced risks of both major adverse cardiovascular events and heart failure hospitalization in the subset of patients with type 2 diabetes and prior myocardial infarction versus controls (Circulation. 2019 May 28;139[22]:2516-27). The absolute risk reduction for major adverse cardiovascular events was 1.9% (HR, 0.81; 95% CI, 0.65-1.00; P = .046), while it was 0.6% for heart failure hospitalization (HR, 0.85; 95% CI, 0.72-1.00; P = .055).
These and other studies “speak volumes about the efficacy of managing blood sugar and addressing our biggest nemesis, which is cardiovascular disease,” Dr. Roberts said. “It’s irrefutable. The data [are] very good.”
Dr. Paauw said an SGLT2 inhibitor or GLP-1 receptor agonist is best reserved for use in select patients with cardiovascular risks and type 2 diabetes that need management beyond metformin.
For example, they might fit a 70-year-old with persistent hypertension who’s already taking a couple of blood pressure medications. “If they have another cardiovascular risk factor, the cardiovascular protection piece will be a bigger deal,” he said. Also, “it will probably help lower their blood pressure so they can avoid taking another blood pressure medicine.”
Trials of both GLP-1 receptor agonists and SGLT2 inhibitors have shown benefits “in improving [major adverse cardiac events], with the SGLT2 class showing substantial benefit in improving both heart failure and renal outcomes as well,” noted Dr. Skolnik. “It is in this context that one must address the question of whether the price of the medications are worthwhile. With such substantial benefit, there is no question in my mind that – for patients who have underlying cardiovascular illness, which includes patients with existent coronary disease, history of stroke, transient ischemic attack, or peripheral vascular disease – it is far and away worth it to prescribe these classes of medications.”
Indeed, the American Diabetes Association and the European Association for the Study of Diabetes’ most recent guidelines now call for a GLP-1 receptor agonist – instead of insulin – to be the first injectable used to treat type 2 diabetes (Diabetes Care 2018 Dec; 41[12]:2669-701).
“For the relatively small number of my patients who have been able to access and use these medications for months or longer, more have tolerated the GLP-1 agonists than SGLT2 inhibitors primarily due to urinary issues,” noted Dr. Hopkins.
Dipeptidyl peptidase–4 inhibitors are another option in patients with type 2 diabetes, but research suggests they may not be a top option for patients with cardiovascular risk. A 2018 review noted that cardiovascular outcome trials for alogliptin (Nesina), saxagliptin (Onglyza), and sitagliptin (Januvia) showed noninferiority but failed to demonstrate any superiority, compared with placebo in patients with type 2 diabetes mellitus and high cardiovascular risk (Circ Res. 2018 May 11;122[10]:1439-59).