Associations between usual glycated haemoglobin and cardiovascular disease in patients with type 2 diabetes mellitus: A 10-year diabetes cohort study.

AIM: To investigate the assocation between glycated haemoglobin (HbA1c) level and cardiovascular disease (CVD) risk among patients with type 2 diabetes. MATERIALS AND METHODS: This retrospective cohort study conducted in Hong Kong selected patients aged 45 to 84 years with type 2 diabetes mellitus and without CVD from primary care clinics during the period 2008 to 2010. Usual HbA1c measurement was calculated using a mixed-effects model to minimize regression dilution bias. The association between usual HbA1c and CVD risk was assessed by Cox regression, with adjustment for baseline covariates. Subgroup analyses by patient characteristics were also conducted. RESULTS: After a median follow-up period of 8.4 years (1.4 million person-years), 174 028 patients with 34 074 CVD events were observed. A curvilinear association was found between usual HbA1c and total CVD, stroke, heart failure and CVD mortality risk. No significant difference was found among patients with usual HbA1c <53 mmol/mol (7%). A positive linear association was found between usual HbA1c and the risks of outcomes when the usual HbA1c was 53 mmol/mol (7%) or above. The adjusted hazard ratios (HRs) for CVD risk per 1% increment in usual HbA1c >7% was 21% (HR 1.21, 95% confidence interval [CI] 1.18-1.23) (HR for CVD per 1mmol/mol increment in usual HbA1c > 53 mmol/mol was 1.7% (HR 1.017, CI 1.015-1.019)). A similar pattern was identified in a patient subgroup analysis, but the effects of usual HbA1c in younger patients were more prominent than in older patients. CONCLUSIONS: Usual HbA1c increments for levels >53 mmol/mol (7.0%) were associated with elevated CVD risk, but no difference was found in the population with usual HbA1c <53 mmol/mol (7.0%), irrespective of patient characteristics. For CVD prevention, strict adherence to an HbA1c target of <53 mmol/mol (7%) should apply to younger patients.

Validation of a nomogram for predicting regression from impaired fasting glucose to normoglycaemia to facilitate clinical decision making.

BACKGROUND: In Hong Kong, fasting plasma glucose (FPG) is the most popular screening test for diabetes mellitus (DM) in primary care. Individuals with impaired fasting glucose (IFG) are commonly encountered. OBJECTIVES: To explore the determinants of regression to normoglycaemia among primary care patients with IFG based on non-invasive variables and to establish a nomogram for the prediction of regression from IFG. METHODS: This cohort study consisted of 1197 primary care patients with IFG. These subjects were invited to repeat a FPG test and 75-g 2-hour oral glucose tolerance test (2h-OGTT) to determine the glycaemia change. Normoglycaemia was defined as FPG <5.6 mmol/L and 2h-OGTT <7.8 mmol/L. Stepwise logistic regression model was developed to predict the regression to normoglycaemia with non-invasive variables, using a randomly selected training dataset (810 subjects). The model was validated on the remaining testing dataset (387 subjects). Area under the receiver operating characteristic curve (AUC) and Hosmer-Lemeshow test were used to evaluate discrimination and calibration of the model. A nomogram was constructed based on the model. RESULTS: After a mean follow-up period of 6.1 months, 180 subjects (15.0%) had normoglycaemia based on the repeated FPG and 2h-OGTT results at follow-up. Subjects without central obesity or hypertension, with moderate-to-high-level physical activity and a lower baseline FPG level, were more likely to regress to normoglycaemia. The prediction model had acceptable discrimination (AUC = 0.705) and calibration (P = 0.840). CONCLUSION: The simple-to-use nomogram could facilitate identification of subjects with low risk of progression to DM and thus aid in clinical decision making and resource prioritization in the primary care setting.