For people with Type 1 diabetes – even those who manage their blood sugar levels well, life is a balancing act, Aaron Kowalski, PhD, told Diagnostics & Imaging Week. They know that the higher their HbA1c level is, the higher their risk is of developing long-term complications such as blindness and kidney disease; but if their blood sugar level gets too low they run the risk of becoming hypoglycemic and driving their car into a tree or passing out at work.
Fear of low blood sugar emergencies often prevents many people from achieving tight control, and remains a constant concern for those who manage their diabetes well, said Kowalski, program director for Metabolic Control at the Juvenile Diabetes Research Foundation (JDRF; New York) and a Type 1 diabetic.
This population of people with diabetes who have been successful in managing their disease can still benefit from using a continuous glucose monitor (CGM) devices, according to a major multi-center trial by the JDRF. Kowalski said that in designing the trial, the researchers decided it needed to be broken into two subgroups of people – those who had not reached targeted HbA1c levels, and those who had. The latter group, he said, often are not well-studied because they are already able to manage their blood sugar levels.
CGM devices, manufactured by several companies and approved by the FDA as an adjunctive therapeutic for diabetes, provide both a real-time snapshot of the glucose levels of a person with diabetes, as well as trend information on whether glucose is moving upwards or downwards, and how fast. Devices also provide warnings when the glucose is becoming too high or too low.
According to the JDRF study, using CGM devices enables people who have achieved excellent control (with HbA1c levels below 7%) to continue to tightly manage their diabetes while cutting down on the frequency of low blood sugars, called hypoglycemia.
"In this group we looked at reduction in hypoglycemic exposure, a problem that can be very dangerous and is a limitation," Kowalski said. "The reason I am so pleased with this paper is that it demonstrates quite convincingly that CGM devices really do help people who are under good control' do even better."
Kowalski told D&IW that the results of this study really resonates with this group of patients because they feel like somebody finally understands that being "at target" is often very difficult and CGM devices can really help.
Surprisingly, he said, in the original cohort (those patients who had not achieved control) the researchers saw a drop-off in benefit in kids and teens, likely because the younger patients weren't using the device as much. In the other group, however, the results showed a benefit across the board.
"I see this as a huge step forward for people with diabetes . . . we hit a population of people who aren't often studied," Kowalski said.
The JDRF noted that the landmark Diabetes Control and Complications Trial (DCCT) showed that with intensive insulin therapy, excellent blood glucose control was obtained, but at the expense of a considerable increase in hypoglycemia. The JDRF study has shown that, with CGM, hypoglycemia can be reduced while maintaining excellent blood sugar control.
Kowalski said that in planning this study, the change in HbA1c was not selected as the primary outcome measure because the researchers did not anticipate being able to lower HbA1c levels in the CGM group, given their already exquisite level of control. He noted that the study group expected that there might even be small and clinically insignificant increases in HbA1c values in the CGM group if the devices were able to help them reduce the frequency of glucose levels below 70 mg/dL. Instead, the CGM group was able to maintain HbA1c levels with less biochemical hypoglycemia, whereas HbA1c levels rose over time in the control group. He noted that all the HbA1c outcomes favored the CGM over the control group.
People with diabetes try to maintain their blood sugar levels between 70 mg/dL and 180 mg/dL. When blood sugar becomes very low, people can become confused, lethargic, and even slip into a coma or die, according to the JDRF. Very high blood sugars can also be dangerous, the organization said. And long term, lack of control increases the risk of developing devastating complications, including eye, kidney, nerve, and heart disease. HbA1c is a measure of long-term blood sugar control; standards of good control are generally below 7% for adults, and below 7.5% to 8% for children, depending on age. According to the DCCT findings, every one-point reduction in HbA1c reduces the risk of long-term complications by about 40%.
Kowalski said that for people who want to manage their diabetes better, he believes the CGM is going to become the new standard of care. For him personally, he says he could not fathom not using the device.
The CGM study was a randomized and controlled trial involving 129 adults and children ranging in age from 8 to 69 at 10 sites, including the Atlanta Diabetes Associates, the Joslin Diabetes Center (Boston), Kaiser Permanente Southern California (San Diego), Nemours Children's Clinic (Jacksonville, Florida), the Lucile Packard Children's Hospital at Stanford University (Palo Alto, California), the Barbara Davis Center for Childhood Diabetes at the University of Colorado Health Sciences Center (Denver), the University of Iowa (Iowa City), the University of Washington (Seattle) and Yale University (New Haven, Connecticut),
It was coordinated by the Jaeb Center for Health Research (Tampa, Florida). All participants had good diabetes control when they enrolled in the trial, and were randomly assigned to either a group that used CGM devices or one using standard finger-stick glucose testing for 26 weeks.
According to the study, for those using CGM devices. the time the blood sugar level was below 70 mg/dL decreased by 37 minutes a day. This compared with a decrease in the control group of only 5 minutes a day. In other words, people in the CGM group spent almost two hours more time per day in the target blood sugar range of 71 to 180 mg/dL compared with the control group, and about half an hour less time per day with glucose values in the potentially dangerous hypoglycemia range. The authors demonstrated a number of other significant benefits in this population including:
• More people in the CGM group had an improvement in HbA1c of more than 0.3% (31% versus 5% in the control group).
• Fewer had a worsening of HbA1c greater than 0.3% (28% vs. 52%).
• More CGM users had a HbA1c level below 7% at 26 weeks (88% vs. 63%).
• More people in the CGM group than the control group had a decrease in HbA1c of more than 0.3% without experiencing a severe hypoglycemic event (28% vs. 5%).
The study is the second major publication resulting from JDRF's CGM trials, established to clinically document the benefits of CGM devices in helping people with type 1 diabetes manage their disease more effectively.
In results published last fall in the New England Journal of Medicine, the JDRF Continuous Glucose Monitoring Study Group reported that CGM substantially improved blood sugar levels without increasing the frequency of hypoglycemia in adults over 25 years of age in a randomized trial of 322 adults and children with type 1 diabetes and HbA1c levels above 7%.