Changes in insulin sensitivity and insulin release in relation to glycemia and glucose tolerance in 6,414 Finnish men.
OBJECTIVE
We evaluated insulin sensitivity and insulin secretion across the entire range of fasting (FPG) and 2-h plasma glucose (PG), and we investigated the differences in insulin sensitivity and insulin release in different glucose tolerance categories.


METHODS
A total of 6,414 Finnish men (aged 57 +/- 7 years, BMI 27.0 +/- 3.9 kg/m2) from our ongoing population-based METSIM (Metabolic Syndrome in Men) study were included. Of these subjects, 2,168 had normal glucose tolerance, 2,859 isolated impaired fasting glucose (IFG), 217 isolated impaired glucose tolerance (IGT), 701 a combination of IFG and IGT, and 469 newly diagnosed type 2 diabetes.


RESULTS
The Matsuda index of insulin sensitivity decreased substantially within the normal range of FPG (-17%) and 2-h PG (-37%) and was approximately -65 and -53% in the diabetic range of FPG and 2-h PG, respectively, compared with the reference range (FPG and 2-h PG <5.0 mmol/l). Early-phase insulin release declined by only approximately -5% within the normal range of FPG and 2-h PG but decreased significantly in the diabetic range of FPG (by 32-70%) and 2-h PG (by 33-51%). Changes in insulin sensitivity and insulin secretion in relation to hyperglycemia were independent of obesity. The predominant feature of isolated IGT was impaired peripheral insulin sensitivity. Isolated IFG was characterized by impaired early and total insulin release.


CONCLUSIONS
Peripheral insulin sensitivity was already decreased substantially at low PG levels within the normoglycemic range, whereas impairment in insulin secretion was observed mainly in the diabetic range of FPG and 2-h PG. Obesity did not affect changes in insulin sensitivity or insulin secretion in relation to hyperglycemia.
Stancáková
Alena
A
Department of Medicine, University of Kuopio and Kuopio University Hospital, Kuopio, Finland.
Javorský
Martin
M
Kuulasmaa
Teemu
T
Haffner
Steven M
SM
Kuusisto
Johanna
J
Laakso
Markku
M
D019540:Area Under Curve; D001786:Blood Glucose / Q000187:drug effects / Q000378:metabolism*; D003430:Cross-Sectional Studies; D005387:Finland / Q000453:epidemiology; D018149:Glucose Intolerance / Q000097:blood / Q000453:epidemiology*; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000378:metabolism* / Q000494:pharmacology*; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000378:metabolism / Q000502:physiology; D008297:Male; D024821:Metabolic Syndrome / Q000097:blood / Q000453:epidemiology*; D008875:Middle Aged; D012016:Reference Values
D001786:Blood Glucose; D007328:Insulin