Effects of nonglucose nutrients on insulin secretion and action in people with pre-diabetes.
To determine whether nonglucose nutrient-induced insulin secretion is impaired in pre-diabetes, subjects with impaired or normal fasting glucose were studied after ingesting either a mixed meal containing 75 g glucose or 75 g glucose alone. Despite comparable glucose areas above basal, glucose-induced insulin secretion was higher (P < 0.05) and insulin action lower (P < 0.05) during the meal than the oral glucose tolerance test (OGTT) in all subgroups regardless of whether they had abnormal or normal glucose tolerance (NGT). However, the nutrient-induced delta (meal minus OGTT) in insulin secretion and glucagon concentrations did not differ among groups. Furthermore, the decrease in insulin action after meal ingestion was compensated in all groups by an appropriate increase in insulin secretion resulting in disposition indexes during meals that were equal to or greater than those present during the OGTT. In contrast, disposition indexes were reduced (P < 0.01) during the OGTT in the impaired glucose tolerance groups, indicating that reduced glucose induced insulin secretion. We conclude that, whereas glucose-induced insulin secretion is impaired in people with abnormal glucose tolerance, nonglucose nutrient-induced secretion is intact, suggesting that a glucose-specific defect in the insulin secretory pathway is an early event in the evolution of type 2 diabetes.
Bock
Gerlies
G
Division of Endocrinology, Diabetes, Metabolism, and Nutrition, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA.
Dalla Man
Chiara
C
Campioni
Marco
M
Chittilapilly
Elizabeth
E
Basu
Rita
R
Toffolo
Gianna
G
Cobelli
Claudio
C
Rizza
Robert
R
D001786:Blood Glucose / Q000378:metabolism; D015992:Body Mass Index; D002096:C-Peptide / Q000097:blood; D005215:Fasting; D005260:Female; D005934:Glucagon / Q000097:blood; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000097:blood / Q000378:metabolism*; D000078790:Insulin Secretion; D008297:Male; D008875:Middle Aged; D011236:Prediabetic State / Q000097:blood / Q000503:physiopathology*
D001786:Blood Glucose; D002096:C-Peptide; D007328:Insulin; D005934:Glucagon