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Lp(a) concentrations and phenotypes in children with insulin-dependent diabetes mellitus
S M Haffner1, M Frangos, J Williamson
1Department of Medicine, University of Texas Health Science Center, San Antonio 78284-7873.
Insights
This study found no significant difference in lipoprotein(a) levels between children with insulin-dependent diabetes mellitus (IDDM) and non-diabetic children. Lp(a) levels were not elevated in young IDDM patients without albuminuria.
Area of Science:
- Cardiovascular Health
- Endocrinology
- Lipid Metabolism
Background:
- Insulin-dependent diabetes mellitus (IDDM) is linked to higher coronary heart disease risk.
- Elevated lipoprotein(a) [Lp(a)] levels are a potential risk factor, but previous studies in IDDM lacked detailed analysis.
- Urinary albumin excretion and apolipoprotein(a) [apo(a)] phenotype data were often missing in prior research.
Purpose of the Study:
- To compare Lp(a) concentrations in children with IDDM versus non-diabetic children.
- To investigate the influence of apo(a) phenotype and albuminuria on Lp(a) levels in young IDDM subjects.
- To assess the relationship between Lp(a) and glycemic control (HbA1c) in IDDM.
Main Methods:
- Compared Lp(a) concentrations in 66 children with IDDM and 18 non-diabetic children (all non-Hispanic white, no albuminuria).
- Analyzed Lp(a) levels in relation to age (pubertal status), sex, apo(a) phenotype, and glycosylated hemoglobin (HbA1c).
- Compared findings with adult non-diabetic subjects from the San Antonio Heart Study.
Main Results:
- Lp(a) concentrations were lower in IDDM subjects (12.0 +/- 2.2 mg/dl) than non-diabetic subjects (20.0 +/- 6.1 mg/dl), but not significantly different (P=0.276).
- Postpubertal subjects, especially males, showed higher Lp(a) levels (P=0.041).
- Higher apo(a) molecular weight correlated with lower Lp(a), but apo(a) size did not differ between diabetic and non-diabetic groups. No significant correlation between Lp(a) and HbA1c was found.
Conclusions:
- Young, normoalbuminuric IDDM subjects do not exhibit increased Lp(a) concentrations compared to non-diabetic peers.
- Lp(a) levels are influenced by pubertal status and apo(a) phenotype, not solely by IDDM status in this cohort.
- The findings do not support elevated Lp(a) as a primary risk factor for coronary heart disease in young, uncomplicated IDDM.
Abstract:
Subjects with insulin-dependent diabetes mellitus (IDDM) have an increased incidence of coronary heart disease. Several studies have suggested that Lp(a) levels may be increased in IDDM subjects, although these studies have been limited by the lack of information on apo(a) phenotype and urinary albumin excretion. We compared Lp(a) concentrations in 66 children with IDDM and 18 non-diabetic children; all were non-Hispanic whites and none had detectable albuminuria. Lp(a) concentrations (mg/dl) were lower in subjects with IDDM than in non-diabetic subjects (12.0 +/- 2.2 vs. 20.0 +/- 6.1, respectively), although these means were not significantly different (P = 0.276). Postpubertal subjects, particularly males, had increased Lp(a) concentrations relative to prepubertal subjects (P = 0.041). Higher apo(a) molecular weight was associated with decreased Lp(a) concentrations in both diabetic and non-diabetic subjects. However, apo(a) size was not different in diabetic and non-diabetic subjects. Lp(a) concentrations were not significantly correlated with glycosylated hemoglobin levels in diabetic subjects (r = 0.11, P = NS). We also found similar Lp(a) concentrations in postpubertal IDDM subjects compared with adult non-Hispanic white non-diabetic subjects (n = 208) from the San Antonio Heart Study, a population-based study. These observations do not support increased Lp(a) concentrations in young normoalbuminuric IDDM subjects.