Meta-analysis: Self-monitoring in non-insulin-treated type 2 diabetes improved HbA1c by 0.25%

A meta-analysis of randomized controlled trials of patients with non–insulin-treated type 2 diabetes found that six months of self-monitoring blood glucose reduced hemoglobin A1c (HbA1c) levels by 0.25% more than usual care (mean reduction of 0.88% vs. 0.69%).

The study was published in BMJ on Feb. 17. The following commentary by Laura Rees Willett, MD, FACP, was published in the ACP Journal Club section of the June 19 Annals of Internal Medicine:

Farmer and colleagues combined the published data on glucose self-monitoring in patients with type 2 diabetes not requiring insulin and found a very modest improvement in HbA1c (0.25%), which probably has no clinical significance. The major caveat regarding the validity of the results is that the largest included trial lost 31% of its participants to follow-up. It is difficult to know how this might have changed the results, but sensitivity analysis suggests that the effect would have been minimal.

The clear clinical message from the meta-analysis is that doctors should not routinely recommend glucose self-monitoring to patients with type 2 diabetes not treated with insulin. Self-monitoring is cumbersome and costly, and the benefit in a surrogate marker (HbA1c) is vanishingly small. It is possible that monitoring could have more benefit in selected subpopulations, such as patients needing tight glycemic control or those at higher-than-average risk for hypoglycemia, but this is unproven. Recent trials suggest that the benefits of tight glucose control are less than hoped. More patients are taking such agents as metformin, dipeptidyl peptidase-4 inhibitors, and glucagon-like peptide-1 agonists, which are associated with very low rates of hypoglycemia. It is fairly certain that the subpopulation of patients with diabetes not receiving insulin who would benefit from self-monitoring is quite small.