CGM improved glycemic control in type 1 diabetes with or without pump

Real-time continuous glucose monitoring (CGM), with either an insulin pump or multiple daily injections, was associated with sustained improvements in HbA1c levels compared to self-monitoring of blood glucose, according to a small randomized trial.


Real-time continuous glucose monitoring (CGM) was superior to self-monitoring of blood glucose (SMBG) in reducing HbA1c, hypoglycemia, and other end points in individuals with type 1 diabetes regardless of their insulin delivery method, a study found.

The study enrolled 94 adults who had type 1 diabetes for more than two years and HbA1c levels between 7% and 10% at baseline. Researchers divided participants into four different subgroups based upon patient choice: real-time CGM with multiple daily insulin injections (n=22), CGM with continuous subcutaneous insulin infusion (n=26); SMBG with insulin injections (n=21); and SMBG with insulin infusion (n=25). The main study end points were changes in HbA1c, time in target glucose range (70 to 180 mg/dL [3.9 to 10 mmol/L]), time below range (<70 mg/dL [<3.9 mmol/L]), glycemic variability, and incidence of hypoglycemia. Dexcom Inc., a manufacturer of CGM systems, provided funding for manuscript development. Results were published Sept. 17 by Diabetes Care.

At three years, the patients who used CGM paired with either multiple daily injections or an insulin pump had better HbA1c levels (7.0% and 6.9%, respectively) than participants in the self-monitoring of blood glucose subgroups using either multiple daily injections or an insulin pump (7.7% and 8.0%, respectively). There was no significant difference between the CGM groups. Only the CGM groups saw significant improvements in percentage of time in target range (injection group, from 48.7% to 69.0% [P<0.0001]; infusion group, from 50.9% to 72.3% [P<0.0001]) and time below target range (from 9.4% to 5.5% [P=0.0287] and from 9.0% to 5.3% [P=0.0325], respectively). Seven severe hypoglycemia episodes occurred, five in the SMBG groups and two in the CGM groups.

The results showed comparable improvements in both the CGM groups, which suggests that CGM has equivalent efficacy regardless of the insulin delivery method used, according to the study authors. Real-time monitoring with multiple daily insulin injections can be considered an equivalent but lower-cost alternative to sensor-augmented insulin pump therapy and superior to treatment with SMBG, they said.

The authors noted that the consistently high percentage of time that participants wore their sensors during the study period suggests that CGM was perceived to be a valuable tool. The observed differences might be explained by a significant increase in the number of daily boluses in the CGM group, while there was no change in daily bolusing in the SMBG groups.

ACP Journal Club recently reviewed another study of CGM and insulin pumps. The industry-funded study, published in the June 1 issue of The Lancet Diabetes & Endocrinology, found that in patients with type 1 diabetes and high risk of hypoglycemia, insulin pumps with integrated CGM and suspend-before-low technology reduced hypoglycemic events compared with pumps without either feature.

The commentary noted that limitations of the trial include that it did not compare CGM plus a pump with the suspend-before-low option to either CGM alone or CGM and a pump without the suspend option, which are also effective. “The automated feature may be expected to improve quality of life by reducing the burden of treatment, an effect that may be partially offset in some patients by the technology's high cost,” said the commentary, which was published in the Sept. 17 Annals of Internal Medicine. “Although the benefit reported with pumps with suspend-before-low features is large in patients at high risk for hypoglycemia, clinicians and patients adopting this technology must keep in mind the possibility of prolonged suspension of insulin and its associated risks (i.e., diabetic ketoacidosis, rebound hyperglycemia, and HbA1c elevation).”