People taking insulin for type 2 diabetes may manage symptoms better with a device that constantly checks their blood sugar, a small study suggests.

Researchers focused on 158 adults with type 2 diabetes, all of whom had poorly controlled blood sugar even though they were injecting insulin several times a day.

For the experiment, all of the patients continued using insulin and testing their blood sugar on their own. Researchers randomly assigned half of the participants to also use a continuous glucose monitoring device made by DexCom Inc., which paid for the study and has financial ties to several of its authors.

Patients with type 2 diabetes typically don’t use continuous glucose monitors because the devices can be expensive

After 24 weeks, patients on continuous glucose monitoring did a little better, on average, at managing their blood sugar than the people only using self-testing. But people in both groups typically still had poorly controlled blood sugar at the end of the study.

“The value of continuous glucose monitoring is in the ability to see glucose readings continuously - every five minutes - plus having alarms that indicate that the blood sugar is going up or down,” said lead study author Roy Beck, executive director of the Jaeb Center for Health Research in Tampa, Florida.

“The blood sugar can, if it gets too low, lead to seizure or loss of consciousness, so having the ability to know ahead of time that the glucose levels are trending in that direction is extremely valuable so that the patient can eat or drink carbohydrates to raise the blood sugar,” Beck said by e-mail.

Over time, seeing what types of food raise blood sugar and which exercises can help lower sugar are other advantages of the continuous glucose monitors, Beck said.

“For instance, it is common that a carbohydrate-heavy breakfast will raise the blood sugar considerably, but many patients with type 2 diabetes don’t realise this,” Beck added.

Patients with type 2 diabetes typically don’t use continuous glucose monitors because the devices can be expensive, may not be covered by their insurance plan and might not be recommended by their doctors. DexCom’s continuous glucose monitoring systems can cost more than $1,000.

Currently, the devices are more typically used for patients with type 1 diabetes, which happens when the body doesn’t make insulin and is usually diagnosed in childhood or young adulthood.

The study results suggest that continuous glucose monitoring might make sense for certain patients with type 2 diabetes, said Vanessa Arguello, an endocrinologist at the David Geffen School of Medicine at University of California, Los Angeles, who coauthored an accompanying editorial.

“Continuous glucose monitoring may be unnecessary if people with type 2 diabetes have impeccable glucose control and no (low blood sugar) risk,” Arguello said by e-mail.

But this option might make a big difference for people at high risk of low blood sugar and for patients who really struggle to manage their blood sugars and have dangerously high A1c levels above 9%, Arguello added.