title: Improved meal-related beta-cell function and insulin sensitivity by the dipeptidyl peptidase-IV inhibitor vildagliptin in metformin-treated patients with type 2 diabetes over 1 year.
abstract: OBJECTIVE
  To examine the effects of dipeptidyl peptidase-IV (DPP-4) inhibition on meal-related beta-cell function and insulin sensitivity over 52 weeks in type 2 diabetes.
  
  
  METHODS
  In a 12-week core study, placebo (n = 51) or vildagliptin (n = 56; 50 mg OD) was added to metformin treatment (1.5-3.0 mg/day). A 40-week extension followed in 71 patients. Meal tests were performed at 0, 12, 24, and 52 weeks; glucose, insulin, and C-peptide were evaluated.
  
  
  RESULTS
  In subjects completing 52 weeks with participation in all meal tests (n = 57), HbA(1c) (A1C) decreased in the vildagliptin/metformin group (VM group, n = 31) but increased in the placebo/metformin group (PM group, n = 26; between-group difference -1.0 +/- 0.2%; P < 0.001; baseline of all subjects combined 7.7 +/- 0.1%). Also, fasting glucose decreased in the VM group but increased in the PM group (difference -0.9 +/- 0.3 mmol/l, P = 0.016; baseline 9.8 +/- 0.3 mmol/l). Insulin secretion (postmeal suprabasal area under the 0- to 30-min C-peptide curve divided by the 30-min increase in glucose) was increased in the VM group but was reduced in the PM group (difference +0.011 +/- 0.03 pmol/l 30 min/mmol/l, P = 0.018; baseline 0.036 +/- 0.02). Insulin sensitivity during meal ingestion (oral glucose insulin sensitivity) increased in the VM group but was not altered in the PM group (difference +27 +/- 4 ml x min(-1) x m(-2), P = 0.036; baseline 246 +/- 6). Insulin secretion related to insulin sensitivity (adaptation index) increased in the VM group but decreased in the PM group (difference +3.2 +/- 1.0, P = 0.040; baseline 9.1 +/- 0.5). The change in adaptation index correlated to the change in A1C (r = -0.39, P = 0.004).
  
  
  CONCLUSIONS
  This study presents evidence that DPP-4 inhibition by vildagliptin when added to metformin in type 2 diabetes over 52 weeks improves beta-cell function along with improved postmeal insulin sensitivity.
authors.affiliation: Department of Medicine, Lund University, B11 BMC, SE-221 84 Lund, Sweden. bo.ahren@med.lu.se
authors.forename: Bo
authors.initials: B
authors.lastname: Ahrén
authors.forename: Giovanni
authors.initials: G
authors.lastname: Pacini
authors.forename: James E
authors.initials: JE
authors.lastname: Foley
authors.forename: Anja
authors.initials: A
authors.lastname: Schweizer
mesh_terms: D000218:Adamantane / Q000031:analogs & derivatives* / Q000627:therapeutic use; D019540:Area Under Curve; D001786:Blood Glucose / Q000378:metabolism; D015992:Body Mass Index; D002096:C-Peptide / Q000097:blood / Q000378:metabolism; D018819:Dipeptidyl Peptidase 4 / Q000378:metabolism*; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use; D007328:Insulin / Q000097:blood / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008687:Metformin / Q000627:therapeutic use*; D008875:Middle Aged; D009570:Nitriles; D010919:Placebos; D011480:Protease Inhibitors / Q000627:therapeutic use*; D011759:Pyrrolidines; D000077597:Vildagliptin
chemical_list: D001786:Blood Glucose; D002096:C-Peptide; D007004:Hypoglycemic Agents; D007328:Insulin; D009570:Nitriles; D010919:Placebos; D011480:Protease Inhibitors; D011759:Pyrrolidines; D008687:Metformin; D018819:Dipeptidyl Peptidase 4; D000077597:Vildagliptin; D000218:Adamantane