Blood glucose monitoring is associated with better glycemic control in type 2 diabetes: A database study

BACKGROUND: The value of self-monitoring blood glucose (SMBG) in type 2 diabetes is controversial. OBJECTIVE: To determine SMBG testing rates are positively associated with glycemic control in veterans on oral hypoglycemic agents (OHA). DESIGN: Observational database study. SUBJECTS: Southwestern Healthcare Network veterans taking OHA in 2002 and followed through the end of 2004. MEASUREMENTS: OHA and glucose test strip (GTS) prescriptions were derived from pharmacy files. Subjects were categorized into five groups according to their end-of-study treatment status: group 1 (no medication changes), group 2 (increased doses of initial OHA), group 3 (started new OHA), group 4 (both OHA interventions), and group 5 (initiated insulin). We then used multiple linear regression analyses to examine the relationship between the SMBG testing rate and hemoglobin A1c (HbA1c) within each group. RESULTS: We evaluated 5,862 patients with a mean follow-up duration of 798 ± 94 days. Overall, 44.2% received GTS. Ultimately, 47% of subjects ended up in group 1, 21% in group 2, 9% in group 3, 8% in group 4, and 16% in group 5. A univariate analysis showed no association between the SMBG testing rate and HbA1c. However, after stratifying by group and adjusting for initial OHA dose, we found that more frequent testing was associated with a significantly lower HbA1c in groups 1, 4, and 5. The effect ranged from -0.22% to -0.94% for every ten GTS/week. CONCLUSIONS: Higher SMBG testing rates were associated with lower HbA1c, but only when stratifying the analyses to control for treatment intensification.