DISSIMILAR ASSOCIATION OF CONVENTIONAL IMMUNE-REACTIVE VERSUS SPECIFIC INSULIN WITH CARDIOVASCULAR RISK-FACTORS - A CONSEQUENCE OF PROINSULINAEMIA

In this study involving 365 non-diabetic elderly Caucasians, we examin ed the relationship of immune-specific insulin (ISI), total immune-rea ctive insulin (IRI), proinsulin (PI) and proinsulin-insulin ratio (PI: ISI) to serum high-density lipoprotein cholesterol (HDL-C), triglyceri de (TG); systolic blood pressure (SBP) and diastolic blood pressure (D BP), mean blood pressure (MBP) and pulse pressure. In a multiple regre ssion analysis, adjusted for age, sex and obesity, a 1.3-fold stronger inverse association with HDL-C levels was found for IRI than for ISI, with a 1.6-fold better fit of the regression equation. The positive a ssociation of insulin with TG was 1.6-fold stronger for IRI compared t o ISI, with a 2.5-fold better fit. In contrast, the positive associati on of IRI with the various blood pressure parameters was 1.5-1.9-fold weaker than for I:SI, with a 2.1-3.8-fold worse fit. Both PI:ISI ratio and PI were independently associated with TG levels, but not with HDL -C. The PI:ISI ratio, but not PI, was associated with blood pressure, but dependent on glycaemia. In conclusion, compared to ISI, IRI overes timates the association of insulin with serum lipids and underestimate s the association of insulin with blood pressure. The use of non-speci fic insulin assays may explain the inconsistencies in the findings of previous epidemiological studies. (C) 1998 Elsevier Science Ireland Lt d. All rights reserved.