LOS ANGELES – In the opinion of Richard Pratley, MD, it’s time for diabetes treatment guidelines to evolve in light of accumulating data from cardiovascular outcome trials in type 2 diabetes.
Dr. Richard Pratley
“They have evolved for the general patient population, and this should apply to older individuals as well,” Dr. Pratley said at the World Congress on Insulin Resistance, Diabetes & Cardiovascular Disease. “My fear is, there is therapeutic nihilism, the idea that by the time someone is 75 years old, the horse is out of the barn and you’re not going to be able to impact outcomes with directed therapy. I don’t think that’s true. Our current treatment guidelines for the treatment of diabetes in older individuals remain focused on glycemic control. It’s not hyperglycemia that’s killing people; it’s heart disease and renal disease.”
According to data from the United Nations, about 12% of the global population is older than 60. By 2050, that number is expected to reach 20%, which will continue to drive an epidemic of diabetes in the near future. Dr. Pratley, medical director of AdventHealth Diabetes Institute in Orlando, pointed out that diabetes in older individuals is not a homogeneous condition. “There are many people in my clinic who had type 1 diabetes diagnosed as kids, but I also have patients who have adult-onset type 1 diabetes,” he said. “We also have type 2 patients who can be diagnosed in their 20s, 30s, or 40s, and there are people who are diagnosed in their 70s and 80s. Now we are learning that there are different subtypes of diabetes; so even type 2 diabetes is not a homogeneous condition. There are people who are more insulin resistant or have more of an insulin secretory defect, and there’s a special type of older-onset type 2 diabetes. When you consider all this in talking about diabetes treatments, about 30% of patients in the United States are diagnosed [when they are] over the age of 60, so this is an ongoing issue.”
Older adults with diabetes may have longstanding diabetes with associated microvascular and macrovascular complications, he continued, or they may have newly diagnosed diabetes with evidence of end organ complications at the time of presentation. Or, they may have newly diagnosed diabetes without evidence of complications. “Does this matter? It does,” Dr. Pratley said. “The things we worry about with all patients with diabetes are the microvascular complications, but I would argue that the macrovascular complications, particularly diabetic nephropathy, are things we should have a laser focus on, because they have high morbidity and mortality, especially in older individuals.”
There are more than 28 cardiovascular outcomes trials in patients with type 2 diabetes ongoing or completed, and involving eight classes of medications, with more than 200,000 planned participants, Dr. Pratley said. Of those participants, 90,000 are older than 65 years, and 30,000 are older than 75 years. “This is great,” he said. “Not only do these cardiovascular outcome studies give us a lot of information about the safety and efficacy of these drugs in the general population, we can now dig in to this specific patient population.” For example, in cardiovascular outcomes trials with dipeptidyl peptidase–4 (DPP-4) inhibitors, the mean age of patients was 65. About half of the patients were older than 65, and 10%-14% were older than 75.
Investigators in the SAVOR-TIMI 53 trial examined age in one of their subgroup analyses (Diabetes Care. 2015;38:1145-53). In that study with saxagliptin, among people older than 65 who received the study drug, the hazard ratio for major adverse cardiac events (MACE) was 0.92, compared with 1.15 for those younger than 65 (P value for interaction = .058). “So older people did great [on this drug],” Dr. Pratley said. “In fact, they had a bit of a decreased risk.” A similar association was seen in adults aged 75 years and older (HR, 1.01 in those younger than 75 years, vs. 0.95 in those aged 75 years and older; P value for interaction = .673). “This is telling us that saxagliptin is safe in the older population.”
In the EXAMINE trial, in which patients with type 2 diabetes who had had a recent acute coronary syndrome received either alogliptin or placebo, researchers conducted an analysis of patients older and younger than 65 (N Engl J Med. 2013;369:1327-35). They observed no significant interactions on the primary composite cardiovascular outcome in those younger than 65 (HR, 0.91) and those aged 65 and older (HR, 0.98).
Dr. Pratley noted that in cardiovascular outcome trials with sodium-glucose transporter 2 (SGLT2) inhibitors, the mean age of patients was 64, and 48%-50% of them were older than 65. In the EMPA-REG OUTCOME trial of empagliflozin, the hazard ratio for the primary cardiovascular outcome was 1.04 in patients younger than 65 and 0.71 in those aged 65 and older (P = .01; N Engl J Med, 2015;373:2117-28). “That was a significant interaction,” he said. In addition, the hazard ratio for cardiovascular death was 0.72 in those younger than 65, and 0.54 in those aged 65 and older (P = .21). “There was not a significant interaction here, but clearly there was some trending in the older patient population,” Dr. Pratley said.
In the LEADER study of liraglutide in patients with diabetes, the hazard ratio for the primary composite cardiovascular outcome was 0.87 in the overall population, 0.78 in patients younger than 60, and 0.90 in those aged 60 and older (P = 0.27; N Engl J Med. 2016;375:311-22). In a post hoc analysis that stratified LEADER patients into younger than 75 and 75 and older, the researchers observed a 31% reduction in the 75 and older population, compared with a 10% reduction in the younger population (P for interaction = .09; Ann Intern Med. 2019;170[6]:423-6). “This was driven largely by a decrease in nonfatal [myocardial infarction],” said Dr. Pratley, who was one of the study investigators. “But in patients who were 75 years and older, there was a 30% reduction in all-cause mortality in those treated with liraglutide, compared with 12% in those younger than 75 (P for interaction = .22). That interaction is not significant, but the theme here is that older populations do quite well.”
Based on such evidence, he said, In particular, SGLT2 inhibitors and certain GLP-1 receptor agonists may be associated with an additional benefit in older individuals with cardiovascular disease, “perhaps because they’re the ones at highest risk,” Dr. Pratley said. “But we need further studies to better identify those older individuals who may be at highest risk of adverse cardiovascular complications from diabetes and who might benefit from targeted therapies.”
Many questions remain unanswered in efforts to provide optimal care to older adults with diabetes. “One of the problems is being inclusive in the older patient population,” Dr. Pratley said. “We tried to do a study of frail older individuals looking at different treatments and policies. It was difficult to recruit frail older individuals, even though they routinely are treated with the drugs we study in healthier populations. We need to know how to enroll patients, and which investigators are going to do these trials. Who is going to support these trials? Pharma? The NIH?”
Then there’s the question of what appropriate outcomes are in older individuals. “I think we can agree that hemoglobin A1c is a surrogate of microvascular complications,” he said. “Do we need to be looking at outcomes like MACE, hospitalization for heart failure, death, progression of [chronic kidney disease], and perhaps cognitive function, physical function, sarcopenia, and quality of life?”
Dr. Pratley called for the development of a personalized approach to diabetes management that takes into account heterogeneity in disease pathogenesis, comorbidities, and patient preference.
“We need to change the focus to patient-important outcomes: dying, heart attack, strokes, and avoid therapeutic nihilism, which is still pervasive among many practitioners,” he said. “We also need to partner with primary care, because they take care of the majority of older individuals, and they need to understand how we’re evolving the goals of therapy. We need to educate them about the new guidelines and try to get them on board with some of the latest data that will help improve outcomes in our patients. We also need to understand the cost of diabetes and the cost effectiveness of interventions.”
He also recommends the development of a comprehensive evidence base for the use of drugs in older individuals. “I suggest pooled analyses within clinical development programs,” he said. “That’s been done for most development programs, but the phase 3 studies tend to enroll younger, healthier individuals. It would be good to do a meta-analysis across CVOTs [cardiovascular outcome trials] within different classes of medications.”
Dr. Pratley disclosed that all honoraria and fees he receives are directed to AdventHealth. These include serving on the advisory board or as consultant to AstraZeneca, GlaxoSmithKline, Glytec, Janssen, Ligand, Lilly, Merck, Mundipharma, Novo Nordisk, and Sanofi. He also has served as a speaker for AstraZeneca and Novo Nordisk, and has received research support from Lexicon, Ligand, Lilly, Merck, Novo Nordisk, and Sanofi. He receives no direct or indirect compensation.