ADA 2011: Blood Glucose Self-monitoring Reduces Risk of CV Disease in Patients with Diabetes

Compared to usual care, structured self-monitoring of blood glucose may result in lower levels of a key marker of cardiovascular disease risk in patient with type 2 diabetes.

Patients with diabetes experience multiple comorbidities, with cardiovascular (CV) disease being the most frequent cause of death in this patient population. Several biomarkers for predicting CV risk exist, one of which is NT-proBNP (N-terminal pro-B-type natriuretic peptide). Reducing levels of this marker may reduce CV risk in diabetic patients. Based on previous findings from the Structured Testing Program (STeP) study, which showed a benefit of structured self-monitoring of blood glucose (SMBG) compared to usual care in reducing A1C in type 2 diabetics, researchers led by Dr. Oliver Schnell examined whether SMBG would also reduce levels of NT-pro-BNP in patients with type 2 diabetes (T2D). Findings were presented Monday in a poster at the ADA 71st Scientific Sessions in San Diego.

Data in this study were derived from the STeP study and included 483 patients monitored over 12 months. Patients were assigned via stratified cluster-randomized design to either structured SMBG (with a 7-point prior office visit) in conjunction with enhanced usual care (quarterly visits, free blood glucose meters and strips, and office point-of-care A1C capability) or an active control group (ACG) that received enhanced usual care only. NT-proBNP measurements were taken at baseline, 6 months, and 12 months. Elevated CV risk was defined as NT-proBNP levels of 100 pg/mL or greater. “This is a more conservative cut-off [compared to the traditional 125 pg/mL] because we wanted to look at patients potentially at risk versus those who already have CV issues,” explained Schnell.

Results revealed significant increases NT-proBNP levels in the ACG patients over time (41.6 pg/mL to 48.7 pg/mL from baseline to month 12, respectively, p=0.012), but relatively stable levels in the structured SMBG patients (39.1 pg/mL to 42.0 pg/mL from baseline to month 12, respectively, p=0.926). “The increase in the biomarker over time is not surprising in patients whose diabetes is less well-controlled [ie, ACG patients] because of the association between diabetes and CV disease,” said Ildikó Amann-Zalán, MD, PhD, co-investigator in the study.

What is important to note is that the biomarker remained stable in the structured SMBG patients. In fact, the percentage of patients at low CV risk (NT-proBNP ≤100 pg/mL) after 12 months was 70.9% for ACG patients and 80.5% for structured SMBG patients (p=0.037). The researchers then separated patients into low-risk and high-risk groups based on the cut-off of 100 pg/mL at baseline. For the low-risk patients, similar findings were observed: stable NT-proBNP levels for structured SMBG and increased levels for ACG. For the high-risk group, slightly different effects were observed, with ACG patients showing stable levels of the biomarker and SMBG patients showing a decrease, though this was not statistically significant (may be clinically relevant, however).

Whether the reduction in NT-proBNP levels in the structured SMBG patients was a direct effect of reduced A1C remains unclear. “Our results may be related to the whole process involved in the STeP protocol,” explained Amann- Zalán. “Patients in the study also had regular conversations with their physician about the structured SMBG data, made lifestyle changes, and participated in other habits that increased awareness of their health.” It may also be that structured SMBG reduces CV risk by reducing glucose fluctuations, added Schnell. Research has shown glucose variability to be related to CV risk.

Regardless of the reason, the finding of reduced CV risk using structured SMBG is important. “This is really the first study that looks at CV risk factors and SMBG, and the results are very promising,” said Schnell.