This is the continuation of the initial DIAMOND trial. In the initial trial, 102 type 1 diabetic patients were placed on continuous glucose monitoring (CGM) and were compared with 53 control type 1 diabetic patients who simply monitored their blood sugars in the usual fashion (with home glucometers). Both groups were on multiple daily injections (MDI). At the conclusion of this initial trial, the 102 patients who were placed on CGM were then randomized into a control group (simply continue MDI) or the study group and placed on continuous subcutaneous insulin infusion (CSII; insulin pump). Both groups continued using the CGM devices.
The results showed that adding an insulin pump to a patient who is on CGM improves time within the normal blood glucose range, but at the expense of more time in hypoglycemia.
When you look at both phases of this study and other studies conducted in the past, CSII has a clear advantage in safety and efficacy over MDI, CGM has a clear advantage of safety and efficacy in patients on MDI, and the use of CGM shows a clear advantage of safety and efficacy in patients on CSII. However, amongst patients on CGM, CSII use has a slight advantage of efficacy with a slight loss in safety. This would lead one to believe that CGM offers the greatest advantage of safety whether a patient is on CSII or MDI.
In DIAMOND, the treatment group difference in hypoglycemia was largest in participants with less baseline hypoglycemia and higher baseline A1c, suggesting that patients with higher A1cs and no hypoglycemia would be best managed with CGM and MDI (without CSII).
However, I feel that it is important to note that there was a net decrease in hypoglycemia in the CGM and CSII groups when compared with the baseline at the beginning of the initial trial.
I also feel that a confounder that could have been controlled was the use of the freestyle strips in the CSII group compared with the Bayer Contour Next strips in the MDI group (this may have had very little impact, but it is still a possible confounder).
For me and my practice, I feel that it is important to have a patient buy into the best treatment modality for them. This will make them more successful and more engaged with their treatment. I do feel that CGM offers amazing safety features and really cuts down on the frequency of hypoglycemia whether a patient is on a pump or not. I also feel that patients can learn to use insulin pumps in a safe manner to avoid low blood sugars. Finally, the above nuance is quickly becoming moot as the technology of sensors and pump algorithms are truly beginning to achieve the best of both worlds: controlled blood sugar with minimal to no low blood sugars (allowing our patients to have their cake and eat it too, provided that they bolus for it).