IRIS II Study: Sensitivity and specificity of intact proinsulin, adiponectin, and the proinsulin/adiponectin ratio as markers for insulin resistance.
OBJECTIVE
This study was performed to compare the specificity and sensitivity of intact proinsulin, adiponectin, and their ratio (proinsulin/adiponectin) in the prediction of insulin resistance as assessed by the homeostasis model assessment (HOMA) score (> or =2 = resistant).


METHODS
Using a cross-sectional approach, 500 orally treated patients with type 2 diabetes (272 women, 238 men; mean +/- SD age, 64.8 +/- 11.6 years; hemoglobin A1c, 7.0 +/- 1.5%; disease duration, 5.8 +/- 6.1 years) were investigated. Various cutoffs for body mass index-adjusted adiponectin and proinsulin/adiponectin were compared with the established cutoff value of 10 pmol/L for fasting proinsulin.


RESULTS
Fasting proinsulin correlated more closely with the HOMA score (r = 0.560, P < 0.001) than fasting adiponectin (r = -0.204, P < 0.001) or proinsulin/adiponectin (r = 0.355, P < 0.001). For proinsulin, specificity and sensitivity for insulin resistance in correlation to the HOMA score results were 96% and 70%, respectively. At a comparable specificity level to proinsulin, adiponectin did not reach a comparable sensitivity (14%), while the proinsulin/adiponectin ratio almost reached the same sensitivity (65%). Overall, patients with elevated proinsulin had a higher prevalence of micro- and macrovascular disease [odds ratio 1.47 (adiponectin, 1.08; proinsulin/ adiponectin, 1.48) and 1.34 (adiponectin, 1.32; proinsulin/adiponectin, 1.27), respectively].


CONCLUSIONS
Elevation of fasting intact proinsulin seems to be the more specific marker for insulin resistance and increased cardiovascular risk than suppression of fasting adiponectin. Formation of the ratio does not lead to a further increase in the predictive value.
Langenfeld
Matthias R
MR
IKFE Institute for Clinical Research and Development, Mainz, Germany.
Forst
Thomas
T
Standl
Eberhard
E
Strotmann
Hermann-Josef
HJ
Lübben
Georg
G
Pahler
Sabine
S
Kann
Peter
P
Pfützner
Andreas
A
D052242:Adiponectin; D000284:Administration, Oral; D000328:Adult; D015415:Biomarkers / Q000097:blood*; D001786:Blood Glucose / Q000378:metabolism; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000188:drug therapy; D003925:Diabetic Angiopathies / Q000097:blood; D006442:Glycated Hemoglobin / Q000032:analysis; D006706:Homeostasis; D006801:Humans; D007004:Hypoglycemic Agents / Q000008:administration & dosage; D007333:Insulin Resistance / Q000502:physiology*; D036341:Intercellular Signaling Peptides and Proteins / Q000097:blood*; D008954:Models, Biological; D016017:Odds Ratio; D011384:Proinsulin / Q000097:blood*; D012680:Sensitivity and Specificity
D052242:Adiponectin; D015415:Biomarkers; D001786:Blood Glucose; D006442:Glycated Hemoglobin; D007004:Hypoglycemic Agents; D036341:Intercellular Signaling Peptides and Proteins; D011384:Proinsulin