Decrement of postprandial insulin secretion determines the progressive nature of type-2 diabetes.
OBJECTIVE
Type-2 diabetes is a progressive disease. However, little is known about whether decreased fasting or postprandial pancreatic beta-cell responsiveness is more prominent with increased duration of diabetes. The aim of this study was to evaluate the relationship between insulin secretion both during fasting and 2 h postprandial, and the duration of diabetes in type-2 diabetic patients.


METHODS
Cross-sectional clinical investigation.


METHODS
We conducted a meal tolerance test in 1466 type-2 diabetic patients and calculated fasting (M0) and postprandial (M1) beta-cell responsiveness.


RESULTS
The fasting C-peptide, postprandial C-peptide, M0, and M1 values were lower, but HbA1c values were higher, in patients with diabetes duration > 10 years than those in other groups. There was no difference in the HbA1c levels according to the tertiles of their fasting C-peptide level. However, in a group of patients with highest postprandial C-peptide tertile, the HbA1c values were significantly lower than those in other groups. After adjustment of age, sex, and body mass index (BMI), the duration of diabetes was found to be negatively correlated with fasting C-peptide (gamma = -0.102), postprandial C-peptide (gamma = -0.356), M0 (gamma = -0.263), and M1 (gamma = -0.315; P < 0.01 respectively). After adjustment of age, sex, and BMI, HbA1c was found to be negatively correlated with postprandial C-peptide (gamma = -0.264), M(0) (gamma = -0.379), and M1 (gamma = -0.522), however, positively correlated with fasting C-peptide (gamma = 0.105; P < 0.01 respectively). In stepwise multiple regression analysis, M0, M1, and homeostasis model assessment for insulin resistance (HOMA-IR) emerged as predictors of HbAlc after adjustment for age, sex, and BMI (R2 = 0.272, 0.080, and 0.056 respectively).


CONCLUSIONS
With increasing duration of diabetes, the decrease of postprandial insulin secretion is becoming more prominent, and postprandial beta-cell responsiveness may be a more important determinant for glycemic control than fasting beta-cell responsiveness.
Shim
Wan Sub
WS
Department of Internal Medicine, Inha University College of Medicine, Incheon, Korea.
Kim
Soo Kyung
SK
Kim
Hae Jin
HJ
Kang
Eun Seok
ES
Ahn
Chul Woo
CW
Lim
Sung Kil
SK
Lee
Hyun Chul
HC
Cha
Bong Soo
BS
D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D002096:C-Peptide / Q000097:blood; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism*; D018450:Disease Progression; D005215:Fasting / Q000097:blood; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D019518:Postprandial Period; D012044:Regression Analysis; D016008:Statistical Distributions
D015415:Biomarkers; D002096:C-Peptide; D006442:Glycated Hemoglobin; D007328:Insulin