Not all patients with impaired fasting glucoase require the same management: development of a nomogram for predicting regression from impaired fsating glucose to nomoglycaemia for primary care patients in Hong Kong

Abstract

Introduction: Impaired fasting glucose (IFG) is a commonly encountered risk factor for diabetes mellitus (DM) in the primary care setting. Individuals with IFG are recommended for regular oral glucose tolerance test (OGTT) to monitor progression to DM and lifestyle interventions to prevent development of DM, which represent additional burden for these individuals and the healthcare system. Since the IFG group is heterogenous with 25% subjects progressing to DM, 25% regressing to normoglycaemia and 50% remaining in the group over time, identifying factors associated with early regression to normoglycaemia can be a potentially time- and cost-saving strategy to guide resource allocation for IFG patients. This study aims to evaluate the determinants of regression from IFG to normoglycaemia based on the fasting plasma glucose (FPG) levels and other non-invasive variables, and to develop and validate a nomogram that can be used to predict the regression in primary care clinical settings. Methods: A total of 1,197 IFG individuals were invited to repeat a FPG test and 75-gram 2-hour-OGTT to determine the glycemic change within a period of 18 months. 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: 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). Discussion: By simply checking the presence or absence of central obesity, hypertension and assessing physical activity level, all of which are easily obtained yet very important clinical information, clinicians can identify IFG subjects with low-risk of progression to DM and prioritize resource use in the primary care setting. The simple-to-use nomogram further allows clear visualization of the individual risk and inform both the clinicians and the patients on the treatment targets for promoting regression to normoglycaemia.