Correlation between fasting plasma glucose, post prandial glucose and glycated haemoglobin and fructosamine

This study was done to determine the correlation between glucose monitoring by fasting blood glucose or 2 hours postprandial blood glucose with HbA1c and fructosamine in type 2 diabetic patients. A total of 82 patients from the Primary Care Clinic were enrolled in the study. Fasting blood was drawn for fasting plasma glucose (FPG), glycated haemoglobin (HbA1c) and fructosamine. Two hours after a standard breakfast, blood was again drawn for prandial plasma glucose (PPG). Both PPG and FPG significantly correlated with both HbA1c and fructosamine but PPG showed better correlation to HbA1c than FPG (r= 0.604 vs.0.575) whereas that of FPG and PPG were equally correlated to fructosamine (r= 0.566 vs. 0.551). In predicting good glycaemic control (HbA1c < 7.0%), the sensitivity, specificity and positive predictive value of PPG were 75.0%, 80.6% and 82.5% whereas FPG were 81.8%, 58.3% and 70.6% respectively. These results show that PPG correlated better than FPG to HbA1c and both equally correlated to fructosamine levels. Thus, PPG predicted overall glycaemic control better than FPG. Compared to HbA1c, fructosamine correlated least well with mean glucose profiles. Hence, using HbAlc in monitoring overall glycaemic control is better than fructosamine.