Continuous Glucose Monitoring Improves HbA1c in T1D

Patients with type 1 diabetes who use multiple insulin injections daily experienced improved blood glucose with the use of a sensor implanted under the skin that continuously monitors glucose levels, according to 2 studies published in JAMA.^1,2

DIAMOND Study

In the DIAMOND study (Multiple Daily Injections and Continuous Glucose Monitoring in Diabetes; ClinicalTrials.gov identifier: NCT02282397), the researchers randomly assigned 158 adults with type 1 diabetes (mean age: 48 years; 44% women) to continuous glucose monitoring (CGM; n = 105) or usual care (control group; n = 53). All patients were using multiple daily insulin injections and had glycated hemoglobin (HbA1c) values of 7.5% to 9.9%.

In the CGM group, 93% underwent CGM at least 6 days per week in month 6.¹ Average HbA1c reduction from baseline was 1.1% at 12 weeks and 1.0% at 24 weeks in the CGM group vs 0.5% at 12 weeks and 0.4% at 24 weeks in the control group.¹ The researchers noted that adjusted treatment-group difference in mean change in HbA1c from baseline was −0.6% (95% CI, −0.8% to −0.3%) at 24 weeks.¹

Median duration of hypoglycemia was 43 min/d in the CGM group vs 80 min/d in the control group (P =.002).¹ Severe hypoglycemia events occurred in 2 participants in each group.¹

Study limitations included the eligibility criteria, which prevents generalizing results to patients with type 1 diabetes younger than 26 years or those who have HbA1c values outside the range studied. In addition, the researchers noted that the informed consent and run-in phase may have excluded patients who may be less likely to adhere to CGM than patients who were studied.

“Among adults with type 1 diabetes who used multiple daily insulin injections, the use of CGM compared with usual care resulted in a greater decrease in HbA1c level during 24 weeks. Further research is needed to assess longer-term effectiveness, as well as clinical outcomes and adverse effects,” the researchers wrote.

GOLD Study

In the GOLD study (CGM Treatment in Patients With Type 1 Diabetes Treated With Insulin Injections; ClinicalTrials.gov identifier: NCT02092051), researchers randomly assigned 161 adults with type 1 diabetes (mean age: 43.7 years; 45.3% women) to treatment with a CGM system or conventional treatment for 26 weeks, separated by a washout period of 17 weeks. All patients had HbA1c of at least 7.5% and were using multiple daily insulin injections.

Average HbA1c was 7.92% during CGM use vs 8.35% during conventional treatment, translating to a mean difference of −0.43% (95% CI, −0.57% to −0.29%).² Additionally, 6 of 19 secondary outcomes examining psychosocial and various glycemic measures met statistical significance, favoring CGM over conventional treatment.²

Severe hypoglycemia occurred in 5 patients in the conventional treatment group and in 1 patient in the CGM group.² When using conventional therapy, 7 patients experienced severe hypoglycemia during the washout period.²

The researchers highlighted 2 study limitations, including a lack of follow-up in the second treatment period for 19 patients and the fact that the study could not be blinded.

“In this crossover study of persons with type 1 diabetes treated with multiple daily insulin injections, CGM was associated with a mean HbA1c level that was 0.43% less than conventional treatment. Moreover, glycemic variability was reduced by CGM. Subjective well-being and treatment satisfaction were greater during CGM than conventional therapy,” the researchers wrote. “Further research is needed to assess clinical outcomes and longer-term adverse effects.”

Clinical Implications

In an accompanying editorial,³ Mayer B. Davidson, MD, from Charles R. Drew University of Medicine and Science in Los Angeles, California, noted these studies demonstrate the benefit of CGM in certain patients with type 1 diabetes who are using multiple daily insulin injections.

“Additional clinical trials are needed to determine the long-term effect of CGM and whether this approach translates to improved health outcomes and to determine the potential utility of real-time CGM for patients with type 1 diabetes encountered in usual clinical practice and in patients with type 2 diabetes who require insulin injections,” Dr Davidson wrote.

Disclosures: Dexcom Inc provided funding for the DIAMOND study. See the full studies for a complete list of conflicts of interest.

References

1. Beck RW, Riddlesworth T, Ruedy K, et al; for the DIAMOND Study Group. Effect of continuous glucose monitoring on glycemic control in adults with type 1 diabetes using insulin injections: the DIAMOND randomized clinical trial. JAMA. 2017;317(4):371-378.
2. Lind M, Polonsky W, Hirsch IB, et al. Continuous glucose monitoring vs conventional therapy for glycemic control in adults with type 1 diabetes treated with multiple daily insulin injections: the GOLD randomized clinical trial. JAMA. 2017;317(4):379-387.
3. Davidson MB. Continuous glucose monitoring in patients with type 1 diabetes taking insulin injections. JAMA. 2017;317(4):363-364.