Continuous Glucose Monitoring Improves HbA1c in T1D

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The use of CGM compared with usual care resulted in a greater decrease in HbA1c level at 24 weeks.
The use of CGM compared with usual care resulted in a greater decrease in HbA1c level at 24 weeks.

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.
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