Clinical Studies

DIaMonD Study

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Dexcom CGM System demonstrates improvement of several measures of glycemic control in MDI Patients


SUMMARY: The Dexcom DIaMonD study compared continuous glucose monitoring (CGM) with self-monitoring of blood glucose (SMBG) in type 1 adult patients on multiple daily insulin (MDI) therapy. The CGM group showed significant A1C reductions, independent of age, education level, math ability and other factors. The CGM group also spent significantly more time in the euglycemic range, with less hyper- and hypoglycemia, especially at night.

A 24-week, randomized controlled trial of 155 adult patients with type 1 diabetes (≥25 years) compared efficacy of MDI therapy augmented with Dexcom CGM (n = 105) vs. SMBG (n = 53). A1C reduction was the primary endpoint, though the study also measured several indices of glycemic variability, as well as adherence to the assigned blood glucose measurement technology.

At six months, A1C in the CGM group declined on average 1.0% vs. 0.4% in the SMBG group, for an adjusted-mean difference of -0.6% in favor of CGM (p<0.001). Additionally, a subset of participants with a baseline A1C of ≥ 8.5% experienced a dramatic 1.3% A1C reduction. The A1C reductions were remarkably consistent across age, baseline hypoglycemia, education, and diabetes numeracy/math ability. At the same time, the CGM users also experienced less time out of target range, a 79% reduction of median time spent in nocturnal hypoglycemia, and a 40% reduction of median time spent in severe hyperglycemia. 

The CGM users demonstrated remarkably high levels of adherence. At six months, CGM wear >6 days per week was seen in an impressive 93% of patients. This study may help debunk perceptions that CGM is too complicated to use for older or less-educated patients, and also helps prove CGM can help reduce A1C without hypoglycemia risk regardless of insulin delivery method.

Average 1.0%  A1C reduction after 24 weeks* with Dexcom CGM users on an MDI regimen

* Compared to baseline (difference of 0.6% compared to SMBG group)

Dexcom CGM increases time in target range (70-180 mg/dL) by 1.3 hours per day

79%  Reduction of median time spent in nocturnal hypoglycemia with the Dexcom CGM

93% of patients still using the Dexcom CGM System  6 days/week (at week 24)

Sources: Beck RW, Riddlesworth T, Ruedy K, et al. 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. doi:10.1001/jama.2016.19975.

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