Incremental Value of Continuous Glucose Monitoring When Starting Pump Therapy in Patients With Poorly Controlled Type 1 Diabetes: The RealTrend study*

OBJECTIVE

To compare the improvements in glycemic control associated with transitioning to insulin pump therapy in patients using continuous glucose monitoring versus standard blood glucose self-monitoring.

RESEARCH DESIGN AND METHODS

The RealTrend study was a 6-month, randomized, parallel-group, two-arm, open-label study of 132 adults and children with uncontrolled type 1 diabetes (A1C ≥8%) being treated with multiple daily injections. One group was fitted with the Medtronic MiniMed Paradigm REAL-Time system (PRT group), an insulin pump with integrated continuous subcutaneous glucose monitoring (CGM) capability, with instructions to wear CGM sensors at least 70% of the time. Conventional insulin pump therapy was initiated in the other group (continuous subcutaneous insulin infusion [CSII] group). Outcome measures included A1C and glycemic variability.

RESULTS

A total of 115 patients completed the study. Between baseline and trial end, A1C improved significantly in both groups (PRT group −0.81 ± 1.09%, P < 0.001; CSII group −0.57 ± 0.94%, P < 0.001), with no significant difference between groups. When the 91 patients who were fully protocol-compliant (including CGM sensor wear ≥70% of the time) were considered, A1C improvement was significantly greater in the PRT group (P = 0.004) (PRT group −0.96 ± 0.93%, P < 0.001; CSII group −0.55 ± 0.93%, P < 0.001). Hyperglycemia parameters decreased in line with improvements in A1C with no impact on hypoglycemia.

CONCLUSIONS

CGM-enabled insulin pump therapy improves glycemia more than conventional pump therapy during the first 6 months of pump use in patients who wear CGM sensors at least 70% of the time.The long-term clinical benefit of tight glycemic control in type 1 diabetic patients has been demonstrated in several reports by the Diabetes Control and Complications Trial (1,2). To achieve this goal, insulin analogs, basal-bolus multiple daily injections (MDI), and insulin pumps for continuous subcutaneous insulin infusion (CSII) have proved to be important tools for lowering glucose variability and improving glycemic control, leading to higher treatment satisfaction in patients with type 1 diabetes (3–5).Nevertheless, intensive treatment of type 1 diabetes often does not succeed in achieving target A1C levels ≤7.0% (6). Increased self-monitoring of blood glucose (SMBG) levels is correlated with better A1C levels (7,8), but for practical reasons most patients do not perform more than five to seven glucose measurements per day. Consequently, postprandial hyperglycemia and nocturnal hypoglycemia often remain unnoticed, even in individuals with well-controlled diabetes (9–11). Hence, detecting and treating these events might improve the patient''s glycemic control and have an impact on quality of life.Continuous glucose monitoring (CGM) provides information from a subcutaneous glucose sensor on interstitial glucose levels. A typical CGM system incorporates alarms for high and low glucose levels and displays glucose trend information graphically, allowing patients to anticipate hypo- and hyperglycemic events. Recent studies have shown that wearing such devices is associated with improved glycemic control in patients undergoing intensive therapy for type 1 diabetes (12,13) and in patients treated by CSII (14); however, no study has investigated the benefit of CGM in patients with poor metabolic control using MDI upon initiation of pump therapy. In this trial we randomly initiated pump therapy in patients with insufficient metabolic control despite optimized basal-bolus injection regimens with either the MiniMed Paradigm REAL-Time insulin pump (PRT), an insulin pump that can receive and display CGM data from a separate subcutaneous glucose sensor, or conventional CSII, and compared glycemic outcomes after 6 months.