The contribution of postprandial glycemia (PPG) to hyperglycemia has been shown to decrease as HbA1c increased in type 2 diabetic patients. This study aimed at examining, in a series of overweight/obese patients without known glycemic disorder, the contribution of PPG to a “relative” hyperglycemia (glucose values ≥5.5 mmol/L) and the presence of glycemic variability according to HbA1c levels.
Seventy overweight/obese inpatients (body mass index 35.2 ± 6.8 kg/m2) without known glycemic disorder were included. Participants were classified according to an oral glucose tolerance test (according to the American Diabetes Association criteria) as patients with normoglycemia (n = 33), with intermediate hyperglycemia (n = 24) or diabetes (n = 13). They were separated into HbA1c quartiles (Q1 to Q4). A 24 hour continuous glucose monitoring was used under a 1800 kcal diet and minimal physical activity. We assessed PPG contribution (3 hour period after each meal) to the “relative” 24 hour hyperglycemia (glucose values ≥5.5 mmol/L); the remaining time was considered as the fasting/post-absorptive period.
HbA1c range was from 5.1% to 7.4% (32 to 57 mmol/mmol). From the lowest to the highest HbA1c quartile, the area under the curve (AUC) for the “relative” hyperglycemia presented a 17-fold increase for the fasting/post-absorptive (p < 0.001) period and a 7-fold increase postprandially (p < 0.001). The percent of PPG contribution to the “relative” hyperglycemia was calculated with the following formula [100 × (postprandial 3 hour AUC − 3 h AUC for a constant 5.5 mmol/L glycemia)/(total 24 h AUC − 24 h AUC for constant 5.5 mmol/L glycemia)] and decreased from Q1 to Q4 of HbA1c (81.2%, 66%, 65.8%, 57%; p < 0.001). Increasing HbA1c quartiles were associated with higher daily mean blood glucose level (p < 0.001) and higher levels of daily glucose variability indices, including mean amplitude of glycemic excursions (p < 0.01).
In overweight/obese patients, HbA1c was associated with lower PPG contribution to “relative” hyperglycemia and greater glycemic variability. The present findings support the importance of postprandial period in glycemic exposure even before the appearance of diabetes.
Abbreviations:HbA1c (Glycated Hemoglobin), CGM (Continuous Glucose Monitoring), PPG (Postprandial Glycemia), OGTT (Oral Glucose Tolerance Test), GV (Glycemic Variability), BMI (Body Mass Index), AUC (Area under the Curve), MBG (Mean Blood Glucose), MAGE (Mean Amplitude of Glycemic Excursions), SD (Daily Standard Deviation), CV% (Coefficient of Variation), CONGA (Continuous Overlapping Net Glycemic Action), HBGI (High Blood Glucose index), LBGI (Low Blood Glucose Index), LI (Lability Index), MAG (Mean Absolute Glucose), HOMA (Homeostasis Model Assessment)
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Published online: September 26, 2014
Accepted: September 19, 2014
Received: April 10, 2014
☆All authors declare no potential conflict of interest relevant to this article.
☆☆Funding: This research was made possible thanks to the kind provision of GCM devices by Medtronic.
© 2014 Elsevier Inc. Published by Elsevier Inc. All rights reserved.