A study with lots of data
The roughly 5,000 patients enrolled in GRADE were an average age of 57 years old, 64% were men, 66% were White, and 20% were Black. They had had type 2 diabetes, on average, for 4.2 years. Mean body mass index at entry was about 34 kg/m2, average A1c was 7.5%, and average estimated glomerular filtration rate was 95 mL/min/1.73m2. The trial included a 6-12 week run-in period during which background metformin treatment was optimized and led to average A1c levels less than 7%.
Patients were then randomized to one of the four agents as add-on treatment.
Both liraglutide and insulin glargine performed well on many of the numerous metrics in the data-rich trial, largely funded by two branches of the National Institutes of Health, with commercial involvement limited to free supplies of the study drugs.
The secondary metabolic outcome, of disease progressing to a confirmed A1c of 7.5%, was reached by 39% of patients taking insulin glargine, significantly lower than the rate of 46% among patients taking liraglutide, and that rate, in turn, was significantly below the 50% rate among patients taking glimepiride and the 55% rate of those taking sitagliptin.
Mean doses of the second-line agents after 4 years of treatment were 38.3 units/day for glargine, 3.5 mg/day for glimepiride, 1.3 mg/day for subcutaneous liraglutide, and 82.9 mg/day for sitagliptin.
A trio of cardiovascular outcomes showed one significant benefit of liraglutide over the other three drugs for the endpoint of any cardiovascular event, which included not only major adverse cardiovascular events (MACE; cardiovascular death, myocardial infarction, or stroke), but also several other event types, including heart failure requiring hospitalization, unstable angina requiring hospitalization, revascularization or any arterial repairs, stent thrombosis, or transient ischemic attack.
For the endpoint of any cardiovascular event, the rate was 5.8% for patients taking liraglutide, significantly less than the rate of 7.6% of those taking insulin glargine, 8.0% for glimepiride, and 8.6% for sitagliptin, reported John B. Buse, MD, PhD, professor, chief of endocrinology, and director of the Diabetes Center at the University of North Carolina at Chapel Hill.
For each of the other two main cardiovascular endpoints – MACE and hospitalization for heart failure – liraglutide had a numeric advantage over the other three drugs but failed to reach significance.
Patients taking liraglutide also had a smaller but not significantly different point estimate for all-cause death, at 2.1%, compared with 3.1%-3.4% in the other three groups.
And, Dr. Nathan emphasized, the cardiovascular disease data are still considered preliminary.
Liraglutide scored a pair of additional outcome victories. Its use resulted in a significantly lower rate of patients who progressed during follow-up to either needing antihypertensive medications or having their blood pressure rise above 140/90 mm Hg compared with the other three drugs. (At baseline, average blood pressure for all patients was 128/77 mm Hg.)
And after 4 years, patients taking liraglutide lost an average of about 4 kg (8.8 lb) from their baseline weight (which averaged about 100 kg [220 lb]), roughly the same as patients taking sitagliptin but significantly better than with glimepiride or insulin glargine. Patients taking glargine gained a small amount of weight on average during their first couple of years of treatment, roughly 1 kg, but returned to around their baseline weight by the end of 4 years.