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 Metformin, which helps control blood sugar and can be used alone or
in combination with insulin to treat type 2 diabetes, also lowered
the risk of developing the disorder in the study group, just not as
much as making healthy lifestyle changes did.
“The lifestyle intervention was more powerful in preventing or
delaying diabetes development during the original three-year
Diabetes Prevention Program and remains more powerful over the
entire 15-year study,” said professor David M. Nathan of George
Washington University in Rockville, Maryland, a coauthor of the new
paper.
“However, there are specific subgroups in which the lifestyle
intervention had an even more powerful effect – specifically, those
older than age 60,” Nathan told Reuters Health by email. Metformin
was relatively more effective in people younger than 60 and those
who were more obese, he said.
The researchers followed up with the surviving participants of a
diabetes prevention study between 1996 and 2001 that compared people
randomly assigned to either an intensive lifestyle intervention or
850 milligrams of metformin twice daily and a group taking a
placebo.
The participants were all overweight or obese and had elevated blood
sugar levels, both factors that put them at very high risk for
developing diabetes.
At the end of that study, the people following the lifestyle
intervention, which included a low-fat, low-calorie diet and 15
minutes of moderate-intensity exercise daily, had a 58 percent lower
risk of having developed diabetes compared to the placebo group.
Those taking metformin were 31 percent less likely to have
progressed to diabetes than those on placebo.
Since the lifestyle intervention had worked so well, all
participants were offered a version of it for one year after the
study concluded.
As of 2014, almost 90 percent of the original group, or 2,776
people, had been followed since the end of the first study, and
based on their original group assignments, they were offered
lifestyle reinforcement seminars twice yearly or continued to
receive metformin.
After an average of 15 years, diabetes incidence was lower by 27
percent in the lifestyle intervention group and 18 percent in the
metformin group compared to the placebo group.
In 2014, 55 percent of the lifestyle group, 56 percent of the
metformin group and 62 percent of the placebo group had been
diagnosed with diabetes, according to the results in The Lancet
Diabetes and Endocrinology.
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The researchers also tested for changes in the tiny blood vessels of
the kidney and retina and for nerve damage over time, all of which
are associated with diabetes. The presence of these “microvascular
complications” did not differ between groups overall. But among
women in particular, the lifestyle group was less likely to show
this kind of damage.
People who did not develop diabetes were almost 30 percent less
likely to have kidney, retina or nerve damage than those who did.
“The complications that we were studying represent the early
manifestations of this microvascular disease and were generally
asymptomatic,” Nathan said. “It usually takes 10-20 years for these
complications to become clinically serious.”
It was surprising that although lifestyle changes did reduce the
risk of diabetes, they did not always reduce the risk of
microvascular complications, according to Dr. Anoop Misra, director
of Diabetes and Metabolic Diseases for Diabetes Foundation India,
who authored a commentary alongside the new results.
“Metformin could be especially useful in people who are unable to
follow diet and exercise strictly, who are obese, have polycystic
ovarian disease, or cannot walk or exercise due to physical
infirmity,” Misra told Reuters Health by email. “It is a low cost
drug, and could be useful in underprivileged populations also.”
As the American Diabetes Association recommends, Nathan said,
lifestyle interventions should be the first choice for diabetes
prevention, with metformin recommended for younger and more obese
people.
SOURCE: http://bit.ly/1iIGAO8 The Lancet Diabetes and Endocrinology,
online September 13, 2015.
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