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Changes in endogenous insulin secretion during childhood as expressed by plasma and urinary C-peptide
Z Laron1, Y Aurbach-Klipper, B Flasterstein
1Department of Pediatrics, Beilinson Medical Center, Sackler Faculty of Medicine, Tel Aviv University, Israel.
Insights
Basal fasting plasma C-peptide (CP) and insulin levels increase with age in children and adolescents. Female adolescents show higher CP and insulin levels than males during puberty.
Area of Science:
- Pediatric Endocrinology
- Metabolic Research
- Human Physiology
Background:
- Insulin and C-peptide are key biomarkers of pancreatic beta-cell function.
- Understanding normal physiological ranges is crucial for diagnosing metabolic disorders.
- Age-related changes in insulin and C-peptide secretion during childhood and puberty are not fully characterized.
Purpose of the Study:
- To establish normative basal fasting values for plasma C-peptide (CP), plasma insulin, and 24-hour urine CP.
- To analyze how these values change with age, sex, and pubertal development in healthy children and adolescents.
- To investigate potential sex differences in CP and insulin levels during puberty.
Main Methods:
- Cross-sectional study involving 224 normal, non-obese subjects aged 1 to 20 years.
- Measurement of basal fasting plasma C-peptide (CP) and insulin levels.
- Collection and analysis of 24-hour urine samples for C-peptide (CP) excretion.
- Data stratified by age, pubertal rating, sex, and bone age (BA).
Main Results:
- Plasma CP and insulin levels increased from early childhood (1-2 years) to pre-puberty (8-10 years) in both sexes.
- Urine CP levels also showed an increase with age during childhood.
- During puberty, plasma and urine CP and plasma insulin levels peaked at pubertal stage P3, with significantly higher values observed in females compared to males (P < 0.005 for CP).
Conclusions:
- Normal ranges for plasma CP, plasma insulin, and urine CP are established for children and adolescents aged 1-20 years.
- Significant increases in these markers occur with age and pubertal maturation.
- Females exhibit higher CP and insulin levels than males during puberty, indicating potential sex-specific physiological differences in beta-cell function.
Abstract:
Basal fasting values of plasma C-peptide (CP), plasma insulin and 24 h urine CP were determined in 224 normal non-obese subjects of both sexes ranging in age from 1 to 20 years. Analysis of the results by age, pubertal rating, sex and bone age (BA) during childhood showed that mean +/- SD plasma CP levels in both sexes rose from 0.07 +/- 0.08 pmol/ml at the age of 1-2 years to 0.21 +/- 0.11 pmol/ml at 8-10 years. Mean +/- SD plasma insulin levels in both sexes rose from 3.2 +/- 4.3 microU/ml at the age of 1-2 years to 5.9 +/- 4.5 microU/ml at 8-10 years. Mean +/- SD urine CP levels rose from 6.5 +/- 2.8 pmol/mg creatinine per 24 h at the age of 2-8 years to 7.7 +/- 3.5 pmol/mg creatinine per 24 h at 8-11 years in both sexes. During puberty, plasma and urine CP and plasma insulin levels rose further to peak at pubertal stage P3, the values in females being higher (CP = 0.32 +/- 0.06 pmol/ml) than those in males (CP = 0.22 +/- 0.06 pmol/ml) (P less than 0.005). Plasma insulin levels in females were 13.2 +/- 6.9 microU/ml and 6.4 +/- 3.1 microU/ml in males (P less than 0.05). Urine CP levels were 14.5 +/- 5.7 pmol/mg creatinine per 24 h and 10.8 +/- 5.4 pmol/mg creatinine per 24 h in females and males respectively (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)