In one of the studies, which was published in June 2, 2021, in the Journal of the American Medical Association (JAMA), researchers observed that people with type 2 diabetes who use insulin may see more benefits from the device than from a traditional blood glucose monitor, for which they periodically prick their skin to test their blood sugar. Researchers tested the effectiveness of the two different monitoring devices in 175 participants with type 2 diabetes who were being treated with insulin. Participants’ average hemoglobin A1C levels, which show average blood sugar levels over about three months, were at 9.1 percent. Readings above 6.5 percent indicate type 2 diabetes, and readings above 8 percent indicate that blood sugar could be better controlled, and this level is associated with an increased risk of complications. At the start of the study, researchers randomly assigned 116 people to use CGMs and 56 people to use traditional blood glucose monitors for eight months. By the end of follow-up, they had average A1C levels of 8 percent with continuous glucose monitoring compared with 8.4 percent with traditional blood glucose monitors. Part of the difference in results may come down to how often patients test their blood when left to their own devices. While the continuous glucose monitors used in the study checked blood sugar levels every five minutes without any action required by patients, the people using traditional blood glucose monitors checked theirs only 1.5 times a day on average. “Glucose levels fluctuate a lot during the day, particularly in patients using insulin, and these one or two measurements often are not representative of glucose levels at other times of the day,” says a coauthor of the study, Roy Beck, MD, PhD, the president and medical director of the Jaeb Center for Health Research Foundation in Tampa, Florida. “So, patients using a blood glucose meter one or two times a day often have no idea that their glucose level might be rising substantially after a meal,” Dr. Beck says. RELATED: FreeStyle Libre 2 Approved by FDA for Children and Adults With Diabetes
Clinical Trial Shows Benefits of Continuous Glucose Monitoring
All the patients in this study were using basal insulin, doses designed to maintain steady blood sugar levels between meals and overnight, but not prandial insulin, which are fast-acting doses taken before meals to avoid rapid swings in blood sugar levels after eating. One limitation of the study is that results may not be generalizable to people with type 2 diabetes who use both basal and prandial insulin doses. Patients also had more supervision and support through the trial than they might in real life, making it possible that results would be different for people who use CGM in the real world — that is, outside a clinical setting. Yet other new research suggests CGM can make a difference for people with type 2 diabetes who are taking insulin to manage their blood sugar. For example, a separate study published in JAMA, also on June 2, 2021, examined data on blood sugar levels for one year before and after people with diabetes started using a CGM and found a clear benefit for those with type 1 and those with type 2 diabetes. This study examined data on 3,806 individuals who initiated using CGM and 37,947 individuals who didn’t — all of whom were treated at Kaiser Permanente facilities in Northern California between 2014 and 2019. RELATED: 9 Signs Your Blood Sugar Is Out of Control
‘Real-World’ Study Also Finds Benefits of CGM for Type 2 Diabetes
Among the CGM initiators, average A1C levels dropped from 8.2 percent 12 months prior to initiation to 7.64 percent 12 months afterward. Over a similar 24-month window, non-initiators saw their average A1C levels dropped much less, from 8.27 percent to 8.18 percent. In addition, the proportion of initiators with type 2 diabetes who achieved A1C levels below 7 percent, when diabetes is considered well managed, increased from 19.7 percent 12 months before initiation to 32.2 percent 12 months afterward. In contrast, the proportion of non-initiators who achieved A1C levels below 7 percent crept up from 18.0 percent to 20.3 percent over a similar 24-month window. And, CGM was also associated with a decline in cases of hypoglycemia and hyperglycemia — dangerously low and high blood sugar levels, respectively — among people with type 2 diabetes. This study has the advantage of being based on real-world patient experiences. But a limitation of this analysis is that it wasn’t a controlled trial like the previously mentioned new study, and it’s possible there were some undetected differences between initiators and non-initiators that might explain their different outcomes. RELATED: What Are the Signs of High and Low Blood Sugar?
Earlier Research on CGM for Type 2 Diabetes Is Mixed
Although the bulk of the research to date on CGM has focused on people with type 1 diabetes, a handful of other studies have found this method of checking blood sugar levels effective for people with type 2 diabetes. A study published in December 2019 in Diabetes, Obesity and Metabolism, for example, found that people with type 2 diabetes who used insulin achieved a 0.24-point larger reduction in A1C with CGM than with traditional blood glucose monitors, a small but statistically significant difference. CGM was also linked to a lower risk of hypoglycemia in this study. Hypoglycemia is a common risk of using insulin, a therapy designed to reduce blood sugar levels, especially when patients don’t do a good job of monitoring glucose levels to get the optimal amount of insulin at the optimal time. A study published in January 2019 in the Journal of Diabetes Research also looked at CGM for people with type 2 diabetes. This study found that people who used CGM achieved an average 0.35-point larger reduction in A1C and had a lower risk of hypoglycemia compared with people who didn’t use CGM. RELATED: 10 Surprising Causes of Blood Sugar Swings
How CGM May Help People With Type 2 Diabetes on Insulin Lower Their A1C
“Patients with type 2 who are on multiple daily injections of long- and short-acting insulins need frequent testing to adjust short-acting doses and prevent hypoglycemia,” says Osama Hamdy, MD, PhD, the medical director of the obesity clinical program and inpatient diabetes program at the Joslin Diabetes Center, and an associate professor at Harvard Medical School in Boston. Beyond this, people with type 2 diabetes who are trying to lose weight and use insulin, oral diabetes medications, or a combination of the two may benefit from CGM to help identify trends in blood sugar levels throughout the day and see what types of eating and exercise habits have the best or worst impact on blood sugar, says Dr. Hamdy, who wasn’t involved in either of the new studies in JAMA. “What I have seen in my practice is that patients using continuous glucose monitoring eat less and make better choices since they immediately see the impact of bigger portions of food or wrong choices on glucose levels,” Hamdy says. “Patients also see, in real time, the benefits of exercise and increased physical activity.” Many people with diabetes are also unaware of how often they experience hypoglycemia until they start using a CGM, which alerts them anytime this happens, Hamdy says. With a traditional blood sugar monitor, individuals would only know if they were hypoglycemic at the brief moments during the day when they decide to test their blood sugar, often missing it when it happens at other times throughout the day. Elderly people who are at increased risk of hypoglycemia may also benefit from using CGM to manage type 2 diabetes, and this technology may benefit women who develop gestational diabetes, a form of the disease that develops for the first time during pregnancy, Hamdy adds. “In few years, continuous glucose monitoring will be the standard of diabetes care for all patients with type 1 and type 2 diabetes,” Hamdy says. “It is just a matter of time.” RELATED: The Best Diabetes Apps, From Blood Glucose Trackers to Food and Exercise Logs
