Real-time continuous glucose monitoring devices and insulin pumps more effectively optimize blood sugar control in some individuals with type 1 diabetes who use the devices as prescribed compared with conventional blood sugar monitoring and insulin delivery methods, a study has shown.
The newer, more expensive technologies are also associated with improvements in treatment satisfaction and quality-of-life measures, although they may be limited to highly motivated patients in expert settings, Hsin-Chieh Yeh, Ph.D., of Johns Hopkins University in Baltimore and her colleagues reported online July 10 in Annals of Internal Medicine (2012 July 10).
To determine whether the mode of intensive insulin therapy has a differential effect on outcomes in individuals with type 1 or type 2 diabetes, and whether outcomes differ by monitoring strategy, the investigators conducted a systematic review to evaluate the effectiveness of blood sugar sensors that constantly monitor glucose levels and pumps that deliver insulin around the clock as needed relative to glucose self-monitoring via frequent finger sticks and multiple daily injections (MDI) of insulin.
Toward this end, they reviewed a total of 33 randomized controlled trials in children and adults, including 19 that compared continuous subcutaneous insulin infusion (CSII) with MDI, 10 that compared real-time continuous glucose monitoring (rt-CGM) with self-monitoring of blood glucose (SMBG), and 4 that compared a sensor-augmented insulin pump with MDI and SMBG. Their analysis showed that CSII had a favorable effect relative to MDI on glycemic control in adults with type I diabetes, and that both methods worked equally well in preventing hypoglycemia.
Their results also suggest that rt-CGM and sensor-augmented pumps improve glycemic control relative to SMBG and MDI/SMBG, respectively, without increasing individuals’ risk of hypoglycemia.
For the analysis, the investigators included studies of adults, adolescents, or children with type 1 or type 2 diabetes that compared CSII with MDI consisting of at least three injections per day; rt-CGM with SMBG consisting of at least three finger sticks per day; and sensor-augmented pumps with MDI/SMBG. "We excluded studies where insulin was used in the CSII arm, because this is not the preferred clinical practice," the authors wrote, noting that they included studies using long- and rapid-acting analogues and/or neutral protamine Hagedorn and regular insulin in the MDI arms, because both regimens are used in current practice.
Those studies that evaluated process measures, intermediate outcomes, quality of life, or severe hypoglycemia were included in the analysis, as were randomized controlled trials and observational studies with a concurrent comparison group that evaluated microvascular or macrovascular outcomes or mortality. Study eligibility was reviewed independently by two investigators, the authors wrote.
With respect to the comparative effectiveness of CSII versus MDI in children and adolescents with type 1 diabetes, "our meta-analysis showed no difference between groups in the HbA1c change from baseline after 16 or more weeks of follow-up," the authors reported. Similarly, the delivery methods appeared to have similar effects on glycemic control and the incidence of severe hypoglycemia in adults with type 2 diabetes. In contrast, CSII showed favorable effect on glycemic control in adults with type 1 diabetes, although the authors acknowledged that this result was influenced by a single study in which participants had higher hemoglobin A1c values at enrollment, "allowing for greater HbA1c lowering compared with other studies where participants were closer to the HbA1c target at enrollment."
Evaluation of the comparative effectiveness of rt-CGM and SMBG showed that the former was associated with the achievement of a lower HbA1c that reached statistical significance but was not clinically meaningful. The effect was slightly greater in studies where sensor compliance was at least 60% or greater, the authors wrote. "We also found that rt-CGM was associated with a lower HbA1c level compared with MDI in individuals 18 years of age or younger," a finding that provides modest support for a recent recommendation in favor of rt-CGM use in children older than 8 years, they stated.
Finally, sensor-augmented pump use was associated with a statistically and clinically significant greater reduction in HbA1c compared with MDI/SMBG use in individuals with type 1 diabetes, but there was not enough evidence to draw definitive conclusions about severe hypoglycemia or quality of life, they authors wrote.
The findings of the systematic review are limited by a number of considerations. The number of studies for each of the comparisons was small, and the authors may have missed unpublished studies, according to the authors. Further, the data are not generalizable to all diabetes patients, "as the management of CSII and rt-CGM are often limited to expert settings and highly motivated patients," and the study did not address the availability, costs, and insurance coverage of the various new technologies, which could be obstacles to their use, they acknowledged.