To systematically review whether the mode of intensive insulin therapy (continuous subcutaneous insulin infusion [CSII] vs. multiple daily injections [MDI]) and/or the mode of blood glucose monitoring (real time-continuous glucose monitoring [rt-CGM] vs. self-monitoring of blood glucose [SMBG]) results in better glycemic control, less hypoglycemia, improved quality of life, and improved clinical outcomes in individuals with type 1 diabetes, type 2 diabetes, and pre-existing diabetes in pregnancy.
MEDLINE®, Embase®, and the Cochrane Central Register of Controlled Trials from inception to July 2011. Additional studies were identified from reference lists and technical experts.
We included randomized controlled trials (RCTs) for all outcomes and observational studies for selected clinical outcomes that compared the effects of CSII with MDI or rt-CGM with SMBG among children, adolescents, or adults with either type 1 or type 2 diabetes, or pregnant women with pre-existing diabetes. We excluded studies that used regular insulin in the CSII arms. Two reviewers evaluated studies for eligibility, serially abstracted data using standardized forms, and independently evaluated study quality. We conducted meta-analyses when there were sufficient data and studies were sufficiently homogeneous.
We included 41 studies (44 publications). RCTs showed no difference in the effect of CSII and MDI on HbA1c (moderate strength of evidence [SOE]) or severe hypoglycemia (low SOE) for children or adolescents with type 1 diabetes, or for adults with type 2 diabetes. In adults with type 1 diabetes, HbA1c decreased more with CSII than with MDI (low SOE), but results were heavily influenced by one study. There was no difference in severe hypoglycemia (low SOE). In children and adults with type 1 diabetes, CSII use was associated with improved quality of life compared with MDI (low SOE). There was insufficient evidence about quality of life for adults with type 2 diabetes. The SOE regarding pregnant women with pre-existing diabetes was either low or insufficient on all outcomes. We found studies of the comparative effectiveness of rt-CGM versus SMBG in individuals with type 1 diabetes only. Compared with SMBG, rt-CGM achieved a lower HbA1c, with greater reductions occurring where sensor compliance was 60 percent or greater (high SOE). There was no difference in the rate of severe hypoglycemia (low SOE) or quality of life (low SOE). Sensor-augmented pump use was associated with a significantly greater reduction in HbA1c compared with MDI/SMBG use in nonpregnant individuals with type 1 diabetes (moderate SOE). The evidence for other outcomes was low or insufficient.
The approach to intensive insulin therapy can be individualized to patient preference that will maximize their quality of life, as both CSII and MDI have similar effectiveness on glycemic control and severe hypoglycemia, except in adults with type 1 diabetes where CSII had a favorable effect on HbA1c. These data also indicate that rt-CGM is superior to SMBG in lowering HbA1c, without affecting the risk of severe hypoglycemia, in nonpregnant individuals with type 1 diabetes, particularly when compliance is high. Sensor-augmented pumps are superior to MDI/SMBG in lowering HbA1c.
Yeh H-C, Brown TT, Maruthur N, et al. Comparative effectiveness and safety of methods of insulin delivery and glucose monitoring for diabetes mellitus: a systematic review and meta-analysis. Ann Intern Med 2012 Jul 10. [Epub ahead of print.]