Kids with type 1 diabetes who spend hours in front of a TV or computer each day may have poorer blood sugar control, a new study suggests.
It's not clear why the relationship exists, and the findings do not prove that "screen time" itself worsens kids' diabetes control.
But factors like obesity, exercise habits and family income did not explain the connection, the study found.
Among 296 children, teens and young adults with type 1 diabetes, those who spent 4 or more hours per day in front of a TV or computer had higher hemoglobin A1C levels -- a measure of blood sugar control over the past few months.
On average, their hemoglobin A1C was 9.3 percent, versus about 8.5 percent among their peers who spent less time in front of a screen.
Experts recommend that adults keep their A1C levels below 7 percent, while levels in children and teens can go as high as 8.5 percent, depending on their age.
The goal of reining in blood sugar is to help curb the risk of long-term diabetes complications -- which range from heart and kidney disease, to nerve damage to vision loss.
Exactly why screen time was connected to blood sugar control in this study is not clear, according to the researchers, led by Dr. Angela Galler of Charite-Universitatsmedizin Berlin in Germany.
One possibility, they say, is that kids who spend more time in front of the TV or computer snack more often. So it may be more difficult to control their blood sugar than when they stick with more-regular meals.
People with type 1 diabetes have to inject insulin every day, generally timed around meals, to control their blood sugar levels.
But while snacking could be a culprit, this study cannot really prove that screen time is at all to blame for the poorer blood sugar control, according to Dr. Sanjeev Mehta, a diabetes specialist who was not involved in the research.
One limitation of the study is that it measured kids' screen time and their blood sugar control at one time point.
"So we cannot say that increased media consumption leads to poorer (blood sugar) control," said Mehta, of the Joslin Diabetes Center and Harvard Medical School in Boston.
Another issue, he told Reuters Health in an email, is that the study did not collect information on diet. So it's not possible to tell whether snacking, or overall eating habits, might explain the findings on screen time.
Mehta said he thinks that screen time would likely play only a small role in why blood sugar control varies from one child to another. But, he added, it's also something that can be controlled.
"For parents," he said, "I think the message is that lifestyle matters, and represents a modifiable aspect of their childrens' lives."
In this study, kids' reported exercise levels were not related to their blood sugar control.
But the relationship between exercise and blood sugar control is complicated, Mehta explained.
The body's response to exercise varies widely, depending on the person and the type and intensity of the exercise. So physical activity may or may not improve hemoglobin A1C.
Despite that, Mehta said, "certainly, there are great benefits to physical activity, including supporting overall cardiovascular health and the child's quality of life."
So careful attention to diet and exercise is important for all young people with diabetes, Mehta said.
As for screen time, the American Academy of Pediatrics recommends that all children and teenagers spend no more than 2 hours a day in front of a TV or computer. That's for various reasons, including getting kids off the couch and giving them enough time for a good night's sleep.