The findings in this report are subject to at least five limitations.
First, BRFSS data are self-reported and subject to recall bias. Therefore,
SMBG rates might be underestimated or overestimated; further investigation of the reliability and validity of self-reported SMBG is needed. Second,
BRFSS excludes persons without landline telephones. Adults with only wireless telephones tend to be younger, to have lower incomes, to be Hispanic, and to have no health insurance coverage.§ As a result, the SMBG rates might be overestimated and might not be generalizable to certain segments of the U.S. population. Third, the median response rate of BRFSS was only 62.5% in 1997 and 51.4% in 2006; however, the potential for bias attributed to selected respondents who refused to be interviewed is low.∥ Fourth, the states using BRFSS diabetes modules varied from year to year. During the past decade,
the number of states collecting data on SMBG ranged from 39 (in 1998
and 1999) to 49 (in 2003), which might have influenced the observed upward trends. However, an average annual increase of 2.3 percentage points was observed in the overall rate, and annual increases of 2.0-2.7
percentage points were observed in age-specific rates when limiting the data analysis to the 25 states reporting data in all years from 1997 to 2006. Finally, a dichotomous variable measuring daily SMBG (i.e., did or did not practice daily) was created for this analysis,
which did not allow for analysis of correlation with the intensity of self-monitoring (i.e., once or multiple times per day).