Value of assessing post prandial blood glucose as a surrogate for fasting blood glucose in an outpatient medical clinic: a descriptive study

Abstract

Objectives: To assess the value of estimation of postprandial blood sugar (PPBS) as a surrogate for fasting blood glucose (FBS) and to estimate the prevalence and profile of patients with diabetes with normal fasting blood sugar and elevated postprandial blood sugar (Isolated postprandial hyperglycaemia). Setting: Diabetic patients attending an outpatient medical clinic. Methods: In 60 consecutive patients with diabetes attending an out-patient medical clinic, capillary blood glucose estimations were carried out in the fasting state (at least after 8 hours of fasting) and postprandial state (two hours after lunch) on the same day. Data on age, sex, and duration of diabetes, weight and type of oral hypoglycaemic therapy were also collected. Results: 47 out of 60 patients studied had both FBS and PPBS moving in the same direction (either normal FBS and PPBS or elevated FBS and PPBS on the same day). Only 8 patients had elevation of postprandial glucose level in the presence of normal FBS. Patients with long duration of diabetes and who are taking multiple oral hypoglycaemic therapies were more likely to show this phenomenon. Conclusion: Estimation of PPBS is reliable as a surrogate for FBS in 4 out of 5 patients with diabetes. Considering the convenience to some patients who find it difficult to undergo fasting, PPBS is a reliable alternative for FBS, especially in the absence of a gold standard test of glycaemic control such as glycosylated haemoglobin estimations.