"All the event rates, if you look at them, everything is a lot better than it was in the 1990s, dramatically better," said study author Dr Elbert Huang, an associate professor of medicine at the University of Chicago.
The study also found that hypoglycaemia, or low blood sugar a side effect of medications that control diabetes has become one of the top problems seen in seniors, suggesting that doctors may need to rethink drug regimens as patients age.
The findings, published online in JAMA Internal Medicine, are based on more than 72 000 adults aged 60 and older with type 2 diabetes. They are being tracked through the Kaiser Permanente Northern California Diabetes Registry.
Researchers tallied diabetic complications by age and length of time with the disease.
Complications worsen with age
People with type 2 diabetes, the most common form of the disease, have too much sugar in the blood. It's estimated that roughly 23 million people have type 2 diabetes in the United States, about half of them older than 60. Many more are expected to develop diabetes in coming years.
In general, complications of diabetes tended to worsen as people got older, the study found. They were also more severe in people who'd lived with the disease longer.
Heart disease was the chief complication seen in seniors who'd lived with the disease for less than 10 years. For every 1 000 seniors followed for a year, there were about eight cases of heart disease diagnosed in those under age 70, about 11 cases in those in their 70s, and roughly 15 cases for those aged 80 and older.
Among those aged 80 or older who'd had diabetes for more than a decade, there were 24 cases of heart disease for every 1 000 people who were followed for a year.
That's a big drop from just a decade ago, when a prior study found rates of heart disease in elderly diabetics to be about seven times higher 182 cases for every 1 000 people followed for a year.
Heart disease isn't the only complication to see drastic declines. Dangerous episodes of high blood sugar have plunged about 10-fold since 2002, while amputations appear to be about three times lower.
Common treatment side-effects
Things are so much better, in fact, that it's the treatment itself that's now become one of the major reasons seniors with diabetes get sick.
Hypoglycaemia due to plummeting blood sugar characterised by weakness, heart palpitations, trembling, sweating, trouble speaking and anxiety is now the third most common nonfatal complication of diabetes in long-term diabetics aged 70 and older, the researchers found.
"Hypoglycaemia is a side effect of therapy and it's not a good thing," Huang said. "It's now more common than [kidney] failure or amputation. That means the side effects of treatment are now more common than the things we're trying to prevent," he said.
An expert who wasn't involved with the study praised its focus on older adults, who make up about half of those living with diabetes in the United States.
"We are getting more and more concerned about the complications that occur in older adults with ongoing treatment," said Dr Gisele Wolf-Klein, director of geriatric education at the North Shore-LIJ Health System in New Hyde Park, NY.
Wolf-Klein, who has studied rates of hypoglycaemia in nursing home residents, says it's an underappreciated problem.
"We need to understand that older diabetics may be continuing to take the same medication they always took, but they've completely changed their lifestyle," said Wolf-Klein.
For example, many seniors struggle to get enough to eat during the day, something doctors may not think to ask about. Metabolism also slows with age, Wolf-Klein said, making drugs that lower blood sugar especially potent in this population.
"We have to remember that because people are living much longer, the way you treat diabetes in a 40-year-old is going to be very different than the way you treat diabetes in an older patient," she said.
Find everything you need to know about hypoglycaemia here.
For more information on hypoglycaemia, visit American Diabetes Association.