Methods for Insulin Delivery and Glucose Monitoring in Diabetes: Summary of a Comparative Effectiveness Review

BACKGROUND: Diabetes mellitus is defined as a group of metabolic diseases characterized by hyperglycemia, which when untreated can lead to long-term complications, including micro- and macrovascular complications. Tight glycemic control with intensive insulin therapy has been suggested to reduce the risk of such complications in several diabetes populations; however, such an approach can also be associated with risks and challenges. There are currently several modalities available to deliver insulin and monitor glucose levels to achieve glycemic goals in diabetic patients. In July 2012, the Agency for Healthcare Research and Quality (AHRQ) published a systematic review on the comparative effectiveness of insulin delivery systems and glucose-monitoring modalities in diabetic patients receiving intensive insulin therapy. Studies from 44 publications included in the review compared the effects of continuous subcutaneous insulin infusion (CSII) with multiple daily injections (MDI) and/or real time-continuous glucose monitoring (rt-CGM) with self-monitoring of blood glucose (SMBG) among children, adolescents, or adults with either type 1 (T1DM) or type 2 diabetes (T2DM), or pregnant women with pre-existing diabetes (either T1DM or T2DM). This comparative effectiveness review evaluated which modality results in improved glycemic control, less hypoglycemia, better quality of life, and/or improved clinical outcomes. The numerous technologies and the challenges that clinicians face when determining which patient population may benefit from different insulin delivery systems and glucose-monitoring approaches motivated AHRQ to synthesize the available information to assist health professionals in making evidence-based practice decisions for their patients. The review also delineates advances in insulin delivery and glucose-monitoring systems, practical methods to achieve tight glycemic control and strategies to minimize associated risks, as well as highlights gaps in research and areas that need to be addressed in the future. OBJECTIVES: To (a) educate health care professionals on the findings from AHRQ’s 2012 comparative effectiveness review on insulin delivery and glucose-monitoring modalities in patients with diabetes; (b) apply review findings to make treatment decisions in clinical practice; and (c) identify shortcomings in the current research and future directions relating to the comparative effectiveness of insulin delivery and glucose-monitoring modalities for patients with diabetes. SUMMARY: The AHRQ systematic review of randomized clinical trials reveals that both insulin delivery modalities (CSII and MDI) demonstrate similar effectiveness on glycemic control and severe hypoglycemia in children and adolescents with T1DM and in adults with T2DM. In adults with T1DM, hemoglobin A1c decreased more with CSII than with MDI with low strength of evidence, but one study heavily influenced these results. In children and adults with T1DM, the use of CSII was associated with improved quality of life compared with MDI, with low strength of evidence, while there was insufficient strength of evidence to make conclusions regarding the quality of life for adults with T2DM. The study investigators suggest that the modality to deliver intensive insulin therapy can be individualized to patient preference in order to maximize quality of life. On all measured outcomes, there was insufficient or low strength of evidence regarding pregnant women with pre-existing diabetes.The AHRQ investigators found studies comparing the effectiveness of glucose-monitoring modalities in individuals with T1DM only. The systematic review demonstrates that rt-CGM is associated with greater lowering of A1c compared with SMBG (high strength of evidence) without affecting the risk of severe hypoglycemia (low strength of evidence) or quality of life (low strength of evidence) in nonpregnant individuals with T1DM, particularly when compliance with device use is high. Additional findings suggest that the use of sensor-augmented insulin pumps (rt-CGM + CSII) is superior to the use of MDI/SMBG use in lowering A1c in nonpregnant individuals with T1DM (moderate strength of evidence). Comparison of other outcome measures did not yield firm conclusions due to low or insufficient evidence.