The study, published January 24, 2020, in JAMA Network Open, followed 127,600 adults with type 2 diabetes for an average of one year after they initiated therapy with either human or analogue insulin. Despite its higher cost, analogue insulin has become more common than human insulin in recent years in part because it can take effect more quickly and last longer, the study authors wrote. One potential risk of insulin and other medicines to lower blood sugar is that they will induce hypoglycemia, or dangerously low blood sugar levels that can lead to complications such as an irregular heartbeat, blurred vision, seizures, and loss of consciousness, according to the Mayo Clinic. Left untreated, hypoglycemia can be fatal. In the current study, though, there wasn’t any difference in the risk of dying from all causes, or from cardiovascular causes in particular, dependent on the type of insulin people used. “From the health point of view, human and analogue insulins appear to be very similar,” says the senior study author, Patrick O’Connor, MD, MPH, of the HealthPartners Institute in Bloomington, Minnesota. “Our study showed no differences in heart attacks, strokes, or death between human and analogue insulins,” Dr. O’Connor says. “Rates of serious hypoglycemia are similar.” RELATED: Diabetes Nearly Doubles the Risk of Heart Failure
Because of Equal Risks in the Short Term, Consider Choosing Human Over Analogue Insulin
At the start of the study, participants were 59 years old on average and had an average body mass index (BMI) of 32.3, meaning they typically had obesity. They also had dangerously high average blood sugar levels, putting them at risk for serious diabetes complications like amputations, blindness, kidney failure, and early death. And the majority of them were diagnosed with hypertension and taking medications to lower their blood pressure. Roughly half of them were current or former smokers, too. A total of 108,672 patients in the study, or about 85 percent, started taking human insulin, while the remainder started on analogue insulin. According to Diabetes.co.uk, both analogue and human insulin are created in a laboratory, but analogue insulin is altered further to become more uniformly used and rapid acting in the body. In the study, researchers evaluated cardiovascular risks associated with both types of insulin for 95,300 participants, following them for up to 2.5 years after they initiated insulin therapy. They excluded people from the final analysis who didn’t consistently fill insulin prescriptions, stopped treatment, or switched from analogue to human insulin or vice versa. By the end of the study, a total of 5,464 patients, or 4.3 percent, had died. Over this same period, about 1.4 percent of participants had a heart attack, 1 percent had a stroke, and 2.4 percent were hospitalized for heart failure. Risks were similar with both types of insulin. These results suggest that, at least for initial treatment, some people may want to opt for human insulin simply because it may be more affordable than analogue insulin, O’Connor says. RELATED: Why Is Insulin So Expensive? (and What to Do if You Can’t Afford It)
Its Observational Model Is Just One Limitation of the Study
The study wasn’t a controlled experiment designed to prove whether or how human versus analogue insulin might directly cause or protect against cardiovascular problems. One limitation of the study is that it didn’t distinguish between long-acting and short-acting forms of insulin, the study team noted. Another drawback is that they relied on pharmacy records of filled insulin prescriptions to determine the impact of insulin on cardiovascular outcomes, and it’s possible not all patients took their insulin as directed. And the study didn’t look at how often patients developed hypoglycemia, which can contribute to cardiovascular issues. It’s also possible that the current study didn’t follow patients long enough to detect meaningful differences in outcomes between human and analogue insulin, says Simon Heller, a fellow of the Royal College of Physicians and a professor of clinical diabetes at the University of Sheffield in the United Kingdom, who wasn’t involved in the study. RELATED: How Heart Disease and Type 2 Diabetes Are Connected
For Long-Term Blood Sugar Management, Analogue Insulin May Be More Effective Than Human Insulin
When it comes to heart outcomes, the results suggest that at least initially it doesn’t matter whether people choose human or analogue insulin, Dr. Heller says. Heller authored an observational study published in Diabetologia that suggested the risk of hypoglycemia is lower for the first five years of insulin therapy and then rises sharply after that point. Analogue insulin can offer less variation day to day in how much it lowers blood sugar, reducing the risk of hypoglycemia, he says. “There is some evidence that hypoglycemia may be associated with cardiovascular disease, so some have speculated that if you use analogue insulin and reduce hypoglycemia, then you might see benefits in reducing cardiovascular disease,” Heller says. Although the new study didn’t assess hypoglycemia, it’s possible that this side effect was less common with analogue insulin and may result in a lower risk of cardiovascular problems over time, Heller says. “While I think it reasonable to initiate treatment with human insulin, particularly in terms of cost, clinicians should be aware of the increasing risk of hypoglycemia and replace human with analogue insulin, particularly if patients have severe hypoglycemia,” Heller says. RELATED: 10 Warning Signs of Low Blood Sugar
