1. Continuous glucose monitoring compared with usual care provides greater reduction in HbA1c.
2. Further research is required to measure long-term effectiveness and clinical outcomes in a typical clinical population.
Evidence Rating Level: 1 (Excellent)
Study Rundown: Continuous glucose monitoring (CGM) in adults with type 1 diabetes may allow for better glycemic control and long-term clinical effectiveness. To date, a majority of clinical trials involving CGM have tested its impact among patients on the insulin pump. The current study was initiated to better understand the role of CGM in diabetics who rely on self-injections of insulin. One hundred and fifty-eight of such patients with HbA1c between 7.5% and 9.9% were randomly assigned to CGM (n = 105) and control (n = 53) groups. After 24 weeks of follow-up, mean HbA1c in the CGM group was reduced by 1.0%, with an adjusted treatment-group difference of -0.6%. Median duration of hypoglycemia was less in the CGM group while severe hypoglycemia episodes were similar across both cohorts.
Overall, the study suggests that CGM may benefit patients with type 1 diabetes by improving their glycemic control. The study is limited in its application to individuals with type 1 diabetes that are older than 26 years that have HbA1c in the narrow range between 7.5% and 9.9%. Future studies may explore longer-term effectiveness and clinical outcomes.
Relevant Reading: Continuous glucose monitoring systems for type 1 diabetes mellitus
In-Depth [randomized clinical trial]: The trial was conducted at 24 endocrinology practices in the United States. Participants with type 1 diabetes older than 25 years of age were randomly assigned into CGM or control groups in a 2:1 ratio. Patients in the CGM group were given a pump and trained on its proper use. Those in the control group performed home blood glucose monitoring at least 4 times daily and injected insulin as needed. Both groups were provided general diabetes education, and follow-up visits occurred at 4, 12, and 24 weeks. HbA1c was measured at baseline, 12 weeks, and at 24 weeks. Changes in HbA1c comprised the primary outcome. Secondary outcomes included duration of hypoglycemia and hyperglycemia.
In total, 158 participants were assigned to CGM (n = 105) and control (n = 53) groups. Mean age was 48 years old, diabetes duration 19 years, and baseline HbA1c 8.6%. Overall visit completion rates were 99% and 98% for CGM and control groups, respectively. Median CGM use was 7 days/week in the intervention group while median blood glucose self-monitoring was 5.1 tests/day in the control group. Mean reduction in HbA1c from baseline was 1.1% at 12 weeks, and 1.0% at 24 weeks in the CGM group, and 0.5% and 0.4% in the control group (p < 0.001). The adjusted treatment difference between the two groups was -0.6% at 24 weeks (95%CI -0.8% to -0.3%; p < 0.001). Duration of hypoglycemia (<70 mg/dL) was lower in the CGM group (43 min/day vs. 80 min/day in control), while severe episodes of hypoglycemia occurred in two participants from each group. Post-hoc analysis at 24 weeks did not reveal differences in median change in total daily insulin dose per kilogram of body weight, median ratio of long-acting to rapid-acting insulin dose, proportion of participants with an increase in number of injections of rapid-acting insulin per day, and mean change in body weight.
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