Glipizide increases plasma insulin but not C-peptide level after a standardized breakfast in type 2 diabetic patients.
Peripheral blood glucose, plasma insulin and C-peptide levels were investigated after giving a standardized breakfast (500 kcal, 60 g carbohydrates) to 10 nonobese Type 2 diabetic patients previously treated by diet alone. Each patient received at random, at 1 week intervals, either 5 mg glipizide (meal + glipizide) or a placebo (meal alone) 30 min before breakfast. Basal values of blood glucose, plasma insulin and C-peptide were similar on both occasions. After meal + glipizide, the blood glucose increase was sharply limited whereas the rise in plasma insulin was steeper and reached twice as high a level. In contrast, the rise in plasma C-peptide was similar in both conditions. Consequently, the areas under the curves (0-300 min) showed a marked reduction in blood glucose after meal + glipizide (2289 +/- 149 versus 3101 +/- 169 mmol X min/1; 2p less than 0.001), associated with a significant increase in plasma insulin (14219 +/- 3261 versus 7591 +/- 1173 microU X min/ml; 2p less than 0.025) but no significant change in plasma C-peptide (342 +/- 45 versus 326 +/- 34 pmol X min/ml; N.S.). The insulin/C-peptide molar ratio was thus significantly increased after meal + glipizide (0.41 +/- 0.06 versus 0.23 +/- 0.04 at the 60th min; 2p less than 0.02). The dissociation between the responses of insulin and C-peptide suggests that a single dose of 5 mg glipizide in Type 2 diabetic subjects may enhance availability of peripheral insulin by extrapancreatic mechanism(s). This phenomenon may result in a higher circulating level of the hormone and therefore represent a further mode of action of sulphonylureas.(ABSTRACT TRUNCATED AT 250 WORDS)
D001786:Blood Glucose / Q000032:analysis; D002096:C-Peptide / Q000097:blood*; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000188:drug therapy; D004435:Eating; D005260:Female; D005913:Glipizide / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D006801:Humans; D007328:Insulin / Q000097:blood*; D008297:Male; D008875:Middle Aged; D013268:Stimulation, Chemical; D013453:Sulfonylurea Compounds / Q000494:pharmacology*
D001786:Blood Glucose; D002096:C-Peptide; D007328:Insulin; D013453:Sulfonylurea Compounds; D005913:Glipizide