Liraglutide and insulin glargine outperformed glimepiride and sitagliptin as single add-on agents to metformin for treating patients with type 2 diabetes in a multicenter U.S. trial that randomized just over 5,000 patients.
. Results were reported at the virtual American Diabetes Association (ADA) 81st Scientific Sessions.
The comparison included two oral medications – the sulfonylurea glimepiride and dipeptidyl peptidase-4 (DPP-4) inhibitor sitagliptin – and two injectable medications – insulin glargine and glucagon-like peptide 1 (GLP-1) receptor agonist liraglutide.
The primary endpoint was change in A1c level and overall glycemic control. Secondary endpoints include changes in weight, as well as cardiovascular, renal, gastrointestinal, and other complications.
For the primary endpoint – keeping A1c levels below 7% – liraglutide and the basal insulin glargine both did this best and were almost equivalent.
During the average 5-year follow-up, the rates of patients progressing to a confirmed A1c of 7% or higher were 67% among patients randomized to insulin glargine, 68% maintained on liraglutide, 72% taking the sulfonylurea glimepiride, and 77% taking sitagliptin, reported John M. Lachin, ScD, a biostatistician at George Washington University, Washington.
Too soon for take-aways, or are the data already obsolete?
“The ultimate goal of GRADE is to help clinicians select the therapies that will work best for individual patients, as diabetes care is not a one-size-fits all approach,” noted David M. Nathan, MD, chair of the study and director of the Diabetes Center at Massachusetts General Hospital, in an ADA press release.
Dr. Nathan, as well as several other members of the GRADE trial steering committee who presented results, repeatedly cautioned that the findings were preliminary because they represent 90% of outcomes, with the remaining 10% still to be adjudicated.
“We undertook this study to fill a gap in the guidelines,” said investigator Deborah J. Wexler, MD, clinical director of the Diabetes Center at Massachusetts General Hospital in Boston. “I would like to have all the results in ... before I comment on how the guidelines should change.”
“The metabolic data are solid, but the cardiovascular disease data are preliminary,” warned Dr. Nathan.
But that didn’t stop some from drawing their own conclusions, with Julio Rosenstock, MD, who comoderated the session but was not involved with the study, giving his own opinion.
“A pleasant surprise was the performance of basal insulin,” he said, calling the findings “a vindication” for basal insulin as a treatment for the types of patients with type 2 diabetes that enrolled in the study.
Steven E. Kahn, MB, ChB, another GRADE co-investigator agreed. “Based on the results, guidelines should say that you add insulin early on,” he observed.
A generic basal insulin and a generic sulfonylurea are both reasonable options, after metformin, for patients with limited resources, added Dr. Kahn, an endocrinologist and professor at the University of Washington, Seattle.
Dr. Rosenstock, director of the Dallas Diabetes Research Center, also saw the results as an indictment of agents in the DDP-4 inhibitor class, such as sitagliptin.
The DPP-4 inhibitors generate $9 billion a year, he said, wondering whether it “is justifiable to put them on the same level as other agents?”
Meanwhile the assigned discussant, David R. Matthews, DPhil, a professor of diabetes medicine at the University of Oxford, England – while congratulating the investigators on certain aspects of the study – said it ultimately fell short because it didn’t include an arm with an SGLT2 inhibitor.
“We should kick the authors for missing out on SGLT2 inhibitors,” Dr. Matthews said. “The omission means that the GRADE data are already obsolescent.”
In reply, Dr. Nathan admitted “we feel bad we did not include” an SGLT2 inhibitor, but he vigorously defended the dilemma faced by the trial’s organizers.
Oral SGLT2 inhibitors were not “well-established drugs” for type 2 diabetes when enrollment launched in 2013, and the researchers were wary of including what could turn out to be a problematic agent soon after controversy over the safety of agents in the thiazolidinedione drug class (such as rosiglitazone), he explained.
They also realized that adding a fifth drug to the study would necessitate doubling enrollment size, which would have undercut the funding plans already in place.
Dr. Matthews also derided GRADE as being underpowered to adequately address the impact of the tested agents on major adverse cardiovascular events (MACE) and hospitalizations for heart failure and too U.S.-centric to be generalizable elsewhere.