Relative and absolute contributions of postprandial and fasting plasma glucose to daytime hyperglycaemia and HbA(1c) in subjects with Type 2 diabetes.
OBJECTIVE
To determine the relative and absolute contributions of postprandial glucose (PPG) and fasting or preprandial plasma glucose (FPG) to daytime hyperglycaemia and HbA(1c) respectively, in persons with type 2 diabetes (T2DM).


METHODS
Subjects (n = 52; 37 men) had 12hr plasma glucose (PG) profiles determined in response to three serial identical test meals. PPG exposure was calculated for each meal. Excess hyperglycaemia was calculated above a PG concentration of 5.5 mmol/l. Fasting hyperglycaemia was the difference between excess hyperglycaemia and PPG exposure. Subjects were divided into three groups according to HbA(1c)-(Gp1:<7.3%;Gp2:7.3%-8.0%;Gp3:>8.0%) and the relative contribution of PPG exposure and fasting hyperglycaemia to excess hyperglycaemia calculated for each meal. The absolute contribution of PPG and fasting hyperglycaemia to excess HbA(1c) (mean HbA(1c)-5.1%) was also calculated.


RESULTS
The relative contributions of PPG exposure to excess hyperglycaemia for the three groups were: 58.3%, 54.3% and 35.4% (P = 0.483-Group 1 vs. Group 2; P = 0.002-Group 2 vs. Group 3) for meal 1; 69.8%, 54.7% and 23.7% (P = 0.163-Group 1 vs. Group 2; P = 0.005-Group 2 vs. Group 3) for meal 2; 85.8%, 70.2% and 48.6% (P = 0.153-Group 1 vs. Group 2; P = 0.046-Group 2 vs. Group 3) for meal 3. Absolute contributions of PPG to excess HbA(1c) in the three groups were 1.4%, 1.6% and 1.3% (P = NS).


CONCLUSIONS
The relative contribution of postprandial glucose to excess hyperglycaemia decreases as glycaemic control deteriorates, being dominant with HbA(1c)</= 7.3%, irrespective of the timing of the meal during the day. However, the absolute contribution of postprandial glucose to excess HbA(1c) does not differ significantly ( approximately 1.5%) with varying glycaemic control.
Peter
R
R
Diabetes Research Unit, University Hospital Llandough, Penarth, UK.
Dunseath
G
G
Luzio
S D
SD
Chudleigh
R
R
Choudhury
S R
SR
Owens
D R
DR
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001786:Blood Glucose / Q000378:metabolism*; D003924:Diabetes Mellitus, Type 2 / Q000097:blood; D005215:Fasting / Q000502:physiology; D005260:Female; D006442:Glycated Hemoglobin / Q000378:metabolism*; D006801:Humans; D006943:Hyperglycemia / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D019518:Postprandial Period / Q000502:physiology
D001786:Blood Glucose; D006442:Glycated Hemoglobin