Panel A shows the medians of all quarterly glycosylated hemoglobin values, with the 25th and 75th percentiles of the yearly values indicated by the vertical lines. The differences between treatments were statistically significant (P<0.001) from three months until the end of the study. Panel B shows the medians of the quarterly mean values for the seven capillary-blood glucose measurements in a 24-hour period in each patient, with the 25th and 75th percentiles indicated by the vertical lines. The differences between treatments were statistically significant (P<0.001) at each of the seven testing times.
Figure 2 — Percentage of patients with type 2 diabetes in quintiles of the HbA1c distribution who self-monitor their blood glucose, according to diabetes therapy. The mean ± SD HbA1c for nondiabetic subjects is 5.27 ± 0.43%. In logistic regression, there was no relationship between HbA1c value and self-monitoring in any diabetes therapy group ( P > 0.5). A : Insulin-treated patients. B : Oral agent–treated patients. C : Diet-treated patients. , Self-monitoring test one or more times per week; , self-monitoring test one or more times per day. , self-monitoring test two or more times per day.
SMBG Chien-Wen Chou MD. Endocrinology & Metabolism Division Chi-Mei Medical Center 8 Jul 2005
A strict glycemic control reduces the risk of the development of micro- and macrovascular complications .
In the U.K. Prospective Diabetes Study, each 1% reduction in HbA1c was associated with a 37% decrease in risk for microvascular complications and a 21% decrease in risk for any end point or death related to diabetes.
In clinical practice, a 3-monthly visit to the general practitioner is recommended for the assessment of glycemic control.
There is now much debate on the effectiveness of self-monitoring of blood glucose (SMBG) as a tool in the self-management of diabetic patients.
SMBG aims at collecting information on blood glucose levels at different time points during the day and allows for the timely identification of high levels.
SMBG has proven effective for patients with type 1 diabetes and patients with type 2 diabetes who are using insulin because the information about a patient’s glucose level is useful to refine and adjust insulin dosages, resulting in an improved glycemic control.
Patients who tested their blood glucose increased with an increasing HbA1c value
Examined by diabetes therapy category, little relationship between HbA1c value and the proportion testing at least once per day or the proportion testing at least once per week
Table 1 — HbA1c values and frequency of blood glucose self-monitoring by patients with type 2 diabetes, according to diabetes treatment The upper limit of normal for HbA1c in the assay system is 6.1%, defined as the mean + 2 SDs (5.27 + 0.86%) for the group of people with fasting plasma glucose <110 mg/dl and 2-h postchallenge glucose <140 mg/dl. 6.5 4.6 39.1 14.6 1 time per day 9.2 21.0 21.1 18.0 1–6 times per week 4.6 9.2 11.1 8.5 1–3 times per month 79.7 65.2 28.7 58.9 Never or <1 time per month Blood glucose self-monitoring (%) 14.9 42.2 51.4 37.1 Proportion with HbA 1c 8 (%) 6.37 8.04 8.29 7.64 Mean HbA 1c value * 27.2 45.5 27.3 100.0 Patient distribution (%) Diet alone Oral agents Insulin All patients
Multiple factors impact upon an outcome such as A1C.
As an example, baseline A1C values may reflect important clinical situations that impact design , particularly when disproportionately high or low .
Patients with A1C close to normal may not show much change with either SMBG or usual care, and inclusion of a large number of such patients in studies may minimize differences between groups.
Very poor glycemic control may also be associated with little benefit of SMBG.
In type 2 diabetic patients with high A1C on maximal dose and number of oral agents , insulin therapy may be the only solution to improve glycemic control and SMBG would be unlikely to influence the outcome.
The number of oral agents per patient was not clearly described in many of the six studies, or if reported, subjects on such a regimen were not always equally divided between intervention and control groups.
Finally, the actual number of SMBG measurements performed in the course of the study or their relationship to meals is not always reported
understanding effectiveness requires that compliance with SMBG frequency and timing also be documented and reported.
For patients whose diabetes is out of control or for those having medication initiated , however, SMBG data can be helpful in creating or modifying the diabetes management regimen.
Persistent fasting hyperglycemia , for example, might indicate excessive hepatic glucose output, and patients experiencing this problem might derive benefit from using metformin (Glucophage), which has been shown to decrease nocturnal hepatic glucose output .
Additionally, patients with persistent postprandial hyperglycemia might derive benefit from taking a short-acting oral agent with meals to either decrease carbohydrate absorption (i.e., an alpha-glucosidase inhibiter such as acarbose [Precose] or miglitol [Glyset]) or stimulate insulin secretion at the time of the meal (i.e., repaglinide [Prandin] or nateglinide [Starlix]).