title: Decrement of postprandial insulin secretion determines the progressive nature of type-2 diabetes.
abstract: 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.
authors.affiliation: Department of Internal Medicine, Inha University College of Medicine, Incheon, Korea.
authors.forename: Wan Sub
authors.initials: WS
authors.lastname: Shim
authors.forename: Soo Kyung
authors.initials: SK
authors.lastname: Kim
authors.forename: Hae Jin
authors.initials: HJ
authors.lastname: Kim
authors.forename: Eun Seok
authors.initials: ES
authors.lastname: Kang
authors.forename: Chul Woo
authors.initials: CW
authors.lastname: Ahn
authors.forename: Sung Kil
authors.initials: SK
authors.lastname: Lim
authors.forename: Hyun Chul
authors.initials: HC
authors.lastname: Lee
authors.forename: Bong Soo
authors.initials: BS
authors.lastname: Cha
mesh_terms: 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
chemical_list: D015415:Biomarkers; D002096:C-Peptide; D006442:Glycated Hemoglobin; D007328:Insulin