Self-monitoring in Patients on Diet or OADs Did Not Predict Better Control

The investigators concluded that, in patients with type 2 diabetes not treated with insulin, self-monitoring did not predict better glycemic control over 3 years.

A group of investigators led by Dr Antonio Nicolucci of the Consorzio Mario Negri Sud in Santa Maria Imbaro, Italy, evaluated the impact of self-monitoring of glucose on glycemic control in patients with type 2 diabetes. A total of 1,896 patients who were treated with diet alone (22%) or oral agents (78%) completed questionnaires every 6 months for 3 years. Multi-level analysis was used to determine the predictive value of self-monitoring frequency on long-term glycemic control. Subgroups of patients were identified based on the frequency of self-monitoring.

The investigators found that 41% of patients checked their glucose levels at least once a week and 10.3% checked at least once a day. The frequency of self-monitoring did not affect long-term glycemic control. Changes in self-monitoring frequency were not associated with changes in HbA1c. Self-monitoring did not predict glycemic control in any of the 8 subgroups identified. In subgroups of patients who monitored glucose mainly to avoid hypoglycemic episodes, self-monitoring was associated with a reduction in the frequency of hypoglycaemic episodes.

The investigators concluded that, in patients with type 2 diabetes not treated with insulin, self-monitoring did not predict better glycemic control over 3 years.

Diabetic Medicine 2005;22:900-6

Publishers Comment: There are at least three possible explanations for the lack of an effect of SMBG in patients. First, patients receive little or no feedback on their results. Second, related to the first, they are not taught the self-management skills required to lower the measured glucose values. Third, in my experience, the vast majority of patients measure their glucose level either fasting or pre- prandially, rather than post-prandially. Fasting values serve neither to educate (there is no information on the effect of meal composition or size) nor to effectively motivate (postprandial values are much higher). Furthermore, there are a limited number of behaviors possible for patients not receiving insulin to counter a high preprandial SMBG value. Options include delaying the meal, eating less (especially carbohydrates), exercising at that point, or, if taking repaglinide, increasing the dose for that meal. Even if taught, given patients’ usual lifestyles, these self-management activities are not very likely to occur. Except for "mild" type 2 diabetes, in which the preprandial glucose values are near normal, the most important determinant of postprandial glycemia is the preprandial level. Therefore, in my view, if SMBG is to be recommended in patients not receiving insulin, it should be carried out before and 1–2 h after a meal to maximize the educational value of how the size and composition of the meal contributes to the postprandial glucose concentration (from the difference between the two SMBG values) and the motivational aspect by showing the patient how high the postprandial glucose level reaches.