An editorial notes that most patients in whom CGM has been compared with self-monitored blood glucose (SMBG) have used insulin pumps; and it is thus unclear whether CGM will improve diabetes control in patients with type 1 diabetes who inject insulin. This study is one of two in JAMA that addresses this important issue by comparing CGM with SMBG in patients with type 1 diabetes who inject insulin. It adds that although these 2 studies clearly show a benefit of CGM compared with SMBG, there are several caveats:
• CGM is expensive, the reduction in Hba1c was modest and the duration of the studies was relatively short.
• CGM is invasive and still requires some SMBG, which may limit the acceptability of CGM for a large number of patients.
• In contrast to relatively straightforward relationships between various insulin preparations and preprandial and postprandial SMBG values, recommended lifestyle and insulin dosage changes based on the direction and degree of CGM trend data are more variable.
• Possible generalisability of these findings to largest group of insulin-requiring patients, those with type 2 diabetes, may be problematic because of their residual endogenous insulin secretion and retained ability to secrete glucagon in response to hypoglycemia- glucose concentrations in these patients vary much less than in patients with type 1 diabetes which may limit the advantage of CGM compared with SMBG only.
The editorial concludes “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.”