title: The relationship between self-monitoring of blood glucose results and glycated haemoglobin in type 2 diabetes: the fremantle diabetes study.
abstract: The benefits of self-monitoring of blood glucose (SMBG) in type 2 diabetes remain contentious. If SMBG data do not accurately reflect HbA(1c), attempts to modify lifestyle/pharmacotherapy will be ineffective. We aimed to determine how well SMBG correlates with HbA(1c) and fasting serum glucose (FSG). Community-based type 2 patients using SMBG provided their highest and lowest pre- and post-prandial glucose results in the week before detailed assessment. The ability of average pre- and post-prandial SMBG to predict HbA(1c)>7.0% was determined by linear regression and receiver operating characteristic (ROC) analyses. Of 1286 patients with known SMBG status, 70% reported using SMBG. Pre-prandial SMBG data were obtained from 554 participants and post-prandial SMBG data from 418. The mean SMBG result and HbA(1c) correlated significantly (pre-prandial r(s)=0.55, post-prandial r(s)=0.47; P<0.001). Areas under the ROC curve (95% confidence limits) were 0.78 (0.74-0.83) and 0.74 (0.69-0.78) for pre- and post-prandial SMBG (P<0.04). The optimal cut-point was 6.5 mmol/L for pre-prandial SMBG (sensitivity 79.3%, specificity 64.4%). Mean pre-prandial SMBG results correlated with FSG (r(s)=0.64, P<0.001) but were on average 1.4 mmol/L lower, consistent with known whole blood vs. plasma differences. Since SMBG values reflect prevailing glycaemia, refinements in their interpretation and application may improve SMBG effectiveness.
authors.affiliation: University of Western Australia, School of Pathology and Laboratory Medicine and Department of Biochemistry, PathWest Laboratory Medicine WA, Fremantle Hospital, Western Australia, Australia.
authors.forename: S A Paul
authors.initials: SA
authors.lastname: Chubb
authors.forename: Kylie
authors.initials: K
authors.lastname: Van Minnen
authors.forename: Wendy A
authors.initials: WA
authors.lastname: Davis
authors.forename: David G
authors.initials: DG
authors.lastname: Bruce
authors.forename: Timothy M E
authors.initials: TM
authors.lastname: Davis
mesh_terms: D001786:Blood Glucose / Q000032:analysis*; D015190:Blood Glucose Self-Monitoring; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000188:drug therapy*; D005215:Fasting; D005260:Female; D005500:Follow-Up Studies; D006442:Glycated Hemoglobin / Q000032:analysis*; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use; D007328:Insulin / Q000627:therapeutic use; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D019518:Postprandial Period; D011379:Prognosis; D012372:ROC Curve
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin; D007004:Hypoglycemic Agents; D007328:Insulin