Clinical Question: In patients with type 2 diabetes who are not using insulin, does home monitoring of blood glucose improve care?
Setting: Outpatient (any)
Study Design: Meta-analysis (randomized controlled trials)
Synopsis: The authors searched databases and reference lists for randomized controlled studies evaluating blood glucose self-monitoring with typical care in patients with type 2 diabetes who were not using insulin. They did not attempt to find unpublished studies. Two authors independently reviewed the studies for inclusion and evaluated the methodologic quality, and two authors independently extracted the data. The study quality was moderate for four of the studies and high for two of the studies. However, patients in the six studies included in this analysis were not blinded. Concealed allocation was not done or not described in any of the studies, allowing the possibility that the patients in the blood glucose monitoring groups were of a different type than those in the control groups. They also were highly motivated patients; patients doing the self-monitoring checked blood glucose levels from twice every other day to six times per day six days per week. The comparison groups in the study did no self-monitoring or monitored urine glucose. In the five studies that compared blood glucose monitoring with no monitoring, A1C levels were nominally but significantly lower in the blood glucose monitoring group (−0.39 percent; 95% confidence interval, −0.56 to −0.21) after approximately six months of monitoring. Blood glucose monitoring did not produce better A1C levels than urine glucose monitoring. Fasting blood glucose levels were not different in the two studies that evaluated them, and quality of life was not different with blood glucose monitoring in the two studies that evaluated it. In one study of more than 700 patients, no serious hypoglycemic episodes occurred in any patient.
Bottom Line: Intensive monitoring of blood glucose in patients with type 2 diabetes not using insulin results in a small decrease in A1C levels but does not change fasting blood glucose levels. Urine glucose monitoring works just as well. More casual monitoring of blood glucose, such as once a day, has not been studied. There is a strong possibility that the weak study design was largely responsible for the difference noted in the study. Blood glucose monitoring is expensive. At the intense level of monitoring used in some of these studies (six times per day), the cost of the monitoring strips can be $2,000 per year. (Level of Evidence: 1a)