Plasma concentration of IGF-I is independently associated with insulin sensitivity in subjects with different degrees of glucose tolerance.
OBJECTIVE
We studied the relationships between plasma IGF-I concentrations and insulin sensitivity in subjects with various degrees of glucose tolerance.


METHODS
A total of 357 nondiabetic subjects, 54 subjects with impaired glucose tolerance and 98 newly diagnosed type 2 diabetic subjects, were consecutively recruited, and anthropometric and biochemical characteristics were collected.


RESULTS
IGF-I concentrations were negatively correlated with age, BMI, waist-to-hip ratio, triglyceride levels, and systolic and diastolic blood pressure. IGF-I concentrations were positively correlated with HDL cholesterol and homeostasis model assessment of insulin sensitivity (HOMA-S). The correlations remained significant after adjusting for sex, age, and BMI. Correlations for HOMA-S with these metabolic and anthropometric variables were of a similar degree and direction to those for IGF-I concentrations. Stepwise linear regression analysis in a model, which included well-known modulators of insulin sensitivity such as sex, age, BMI, glucose tolerance status, family history of diabetes, waist-to-hip ratio, systolic and diastolic blood pressure, HDL cholesterol, and triglyceride levels, revealed that IGF-I concentrations were independently associated with insulin sensitivity accounting for 10.8% of its variation (P < 0.0001). IGF-I concentrations were significantly lower in subjects with World Health Organization (WHO)-defined metabolic syndrome compared with subjects without metabolic syndrome (P < 0.0001). Logistic regression analysis showed that each unit increase in log-transformed IGF-I concentrations was associated with a 90.5% reduction in the risk of WHO-defined metabolic syndrome.


CONCLUSIONS
These data indicate that IGF-I has the characteristics to be a marker for the insulin resistance syndrome. This suggests that low IGF-I levels may be a useful marker for identifying subjects at risk for cardiovascular disease.
Sesti
Giorgio
G
Department of Experimental and Clinical Medicine, University Magna Graecia of Catanzaro, Catanzaro, Italy. sesti@unicz.it
Sciacqua
Angela
A
Cardellini
Marina
M
Marini
Maria Adelaide
MA
Maio
Raffaele
R
Vatrano
Marco
M
Succurro
Elena
E
Lauro
Renato
R
Federici
Massimo
M
Perticone
Francesco
F
D015415:Biomarkers / Q000097:blood; D001786:Blood Glucose / Q000187:drug effects / Q000378:metabolism*; D001794:Blood Pressure; D015992:Body Mass Index; D049628:Body Size; D003924:Diabetes Mellitus, Type 2 / Q000097:blood*; D005260:Female; D018149:Glucose Intolerance / Q000097:blood*; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000097:blood / Q000494:pharmacology*; D007333:Insulin Resistance; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008055:Lipids / Q000097:blood; D008297:Male; D024821:Metabolic Syndrome / Q000097:blood; D008875:Middle Aged; D012016:Reference Values
D015415:Biomarkers; D001786:Blood Glucose; D007328:Insulin; D008055:Lipids; D007334:Insulin-Like Growth Factor I