ASSOCIATION BETWEEN LIPOPROTEIN(A) AND INSULIN-LIKE GROWTH-FACTOR-I DURING PUBERTY AND THE RELATIONSHIP TO MICROALBUMINURIA IN CHILDREN ANDADOLESCENTS WITH IDDM

OBJECTIVE-To study pubertal changes in serum lipoprotein(a) [Lp(a)] an d insulin-like growth factor I (IGF-I) in insulin-dependent diabetes m ellitus (IDDM) and the relationship to microalbuminuria. RESEARCH DESI GN AND METHODS-Seventy-nine children and adolescents (59 with normoalb uminuria, 20 with microalbuminuria) with greater than or equal to 5 ye ars of IDDM were investigated together with 54 healthy control subject s in a cross-sectional study. Fasting serum Lp(a); apolipoprotein (ape ) A-1 and B; total, low-density lipoprotein (LDL), and high-density li poprotein cholesterol; triglycerides; and IGF-I were analyzed as were HbA(1c) and overnight albumin excretion rate (AER). Pubertal developme nt was assessed by Tanner staging. RESULTS-Lp(a), apoB, triglycerides, and total and LDL cholesterol were higher (P < 0.001) and apoA-1 was lower (P = 0.03) in normoalbuminuric IDDM patients than in healthy con trol subjects. Lp(a) was increased during puberty (stages 2-4) in IDDM patients but not in healthy subjects, whereas IGF-I was significantly increased during puberty in healthy control subjects only. In IDDM pa tients Lp(a) correlated to insulin dose, total cholesterol, and LDL ch olesterol, but not to IGF-I, HbA(1c), systolic and diastolic blood pre ssure, diabetes duration, age, or sex. In multiple regression analysis with Lp(a) as the dependent variable, puberty was the only significan t contributor to the regression (r(2) = 0.33,P = 0.008). Microalbuminu ria was seen only in the pubertal stage 4-5. Lp(a) tended to be higher (P = 0.06) as did apoB, whereas IGF-I was lower (P < 0.001) in this g roup than in normoalbuminuric patients of the same pubertal stages. In multivariate analysis, with log AER as the dependent variable, apoB/a poA-1, systolic blood pressure, age, and IGF-I but not Lp(a) added to the regression (r(2) = 0.47, P < 0.0001). CONCLUSIONS-Lp(a) is elevate d during puberty in normoalbuminuric subjects with IDDM, independent o f metabolic control and IGF-I. Lp(a) tends to be further increased in microalbuminuria but does not seem to be a contributing determinant of log AER whereas low IGF-I does. Prospective studies are required to e stablish the temporal relationship between increased Lp(a) and microal buminuria in children and adolescents with IDDM.