Can self-monitoring blood glucose improve glycemic control?

This study investigated the effect of self-monitoring of blood glucose on HbA1c (average blood glucose over last 3 months) in people with type 2 diabetes (T2D). It was determined that self-monitoring reduces HbA1c in the short-term, but not the long-term.

Treatment for T2D includes lifestyle changes (like diet and exercise), and medications that lower blood glucose. Control of blood glucose, measured by HbA1c levels, can prevent the complications of T2D. Self-monitoring involves regular ‘finger prick’ tests to measure the level of glucose in the blood. This may help reduce HbA1c, but the exact effect is still under investigation.

This study examined data from 24 other studies. 5,454 patients with T2D participated in these studies. In each study, participants were randomly divided into one of two groups. Group 1 began self monitoring. Group 2 did no monitoring, self monitored less often, or monitored glucose levels in the urine.

HbA1c was similar in both groups at the start of the study. HbA1c was 0.31% lower in group 1 than in group 2 after 12 weeks, and 0.34% lower after 24 weeks. There was no difference between the groups after 1 year.

After 12 weeks, those in group 1 who started with HbA1c greater than 8%, had a 0.83% reduction in HbA1c after 12 weeks, and a 0.48% reduction after 24 weeks, compared to those in group 2. There was no difference between the groups after 1 year. In those participants whose HbA1c was less than 8% at the start of the study, there was a small reduction in HbA1c by 24 weeks in group 1, but no difference after 1 year.

Participants who tested their blood glucose more than 7 times per week they had a 0.16% reduction in HbA1c at 12 weeks, and a 0.54% reduction at 24 weeks, compared to group 2. When they were testing their blood glucose 7 times per week or less, they had a reduction in HbA1c of 0.48% at 12 weeks, and 0.3% at 24 weeks, compared to group 2. There was no difference between groups after 1 year, regardless of the number of tests each week.

The study concluded that self monitoring of blood glucose leads to slight reductions in HbA1c in the short-term in patients with T2D. Those with high HbA1c appear to receive the greatest benefit.

Differences between the different studies may have limited comparisons. For example, blood glucose was monitored at different frequencies in different studies. The benefit of self monitoring may depend on how often blood glucose is tested.