Contributions of Fasting and Postprandial Plasma Glucose Increments to the Overall Diurnal Hyperglycemia of Type 2 Diabetic Patients

TLDR

Controversy surrounds the relative contributions of postprandial versus fasting glucose to overall hyperglycemia, possibly due to interfering factors. The study investigated how overall glycemic control, as reflected by HbA1c levels, influences diurnal glucose profiles in type 2 diabetic patients. Researchers measured fasting and postprandial plasma glucose at 8:00, 11:00, 14:00, and 17:00 in 290 non‑insulin, non‑acarbose patients, calculating areas under the curve above fasting and above 6.1 mmol/L to quantify postprandial and fasting contributions. Postprandial glucose accounted for 69.7 % of overall hyperglycemia in the lowest HbA1c quintile but fell to 30.5 % in the highest, while fasting glucose rose from 30.3 % to 69.5 %, showing that fasting hyperglycemia becomes dominant as diabetes worsens and reconciling previous conflicting findings.

Abstract

The exact contributions of postprandial and fasting glucose increments to overall hyperglycemia remain controversial. The discrepancies between the data published previously might be caused by the interference of several factors. To test the effect of overall glycemic control itself, we analyzed the diurnal glycemic profiles of type 2 diabetic patients investigated at different levels of HbA(1c).In 290 non-insulin- and non-acarbose-using patients with type 2 diabetes, plasma glucose (PG) concentrations were determined at fasting (8:00 A.M.) and during postprandial and postabsorptive periods (at 11:00 A.M., 2:00 P.M., and 5:00 P.M.). The areas under the curve above fasting PG concentrations (AUC(1)) and >6.1 mmol/l (AUC(2)) were calculated for further evaluation of the relative contributions of postprandial (AUC(1)/AUC(2), %) and fasting [(AUC(2) - AUC(1))/AUC(2), %] PG increments to the overall diurnal hyperglycemia. The data were compared over quintiles of HbA(1c).The relative contribution of postprandial glucose decreased progressively from the lowest (69.7%) to the highest quintile of HbA(1c) (30.5%, P < 0.001), whereas the relative contribution of fasting glucose increased gradually with increasing levels of HbA(1c): 30.3% in the lowest vs. 69.5% in the highest quintile (P < 0.001).The relative contribution of postprandial glucose excursions is predominant in fairly controlled patients, whereas the contribution of fasting hyperglycemia increases gradually with diabetes worsening. These results could therefore provide a unifying explanation for the discrepancies as observed in previous studies.