Age-related change in insulin secretion, metabolic parameters, and body fat distribution among Japanese young obese males: Does 'thrifty phenotype' exist?

F. Katsukawa, S. Tsuji, S. Onishi, H. Yamazaki

Research output: Contribution to journalArticle

Abstract

Age-related change in insulin (IRI) secretion and its relation to metabolic profiles and abdominal fat distribution were studied among 225 obese males (age: 15-39 years). Subjects were divided into three groups according to their ages: those in their teens (10s), twenties (20s), and thirties (30s). IIbA1c and lipid profiles (total cholesterol (TC), triglyceride (TG), and HDL-cholesterol (HDL-C)) were evaluated after an overnight fast. Glucose (Glu) and IRI were measured during 75g-oral glucose tolerance test (GTT). The areas of both visceral (V-fat) and subcutaneous fat (S-fat) were evaluated using CT scan at the umbilical level. There was no difference in BMI among the three groups. A wide variance in IRI responses was observed, and not a few subjects showed typical hyperinsulinemia. Fasting IRI (r = -0.202), IRI area under the curves during GTT (r = -0.158), and insulinogenic index (r = -0.202) correlated negatively with age, whereas fasting Glu (r=0.333) and Glu area (r=0.306) showed positive correlations with age. IRI area correlated positively with fasting Glu (r = 0.256), Glu area (r = 0456), and HbA1c (r = 0.309) in 10s group, but negatively with fasting Glu (r = -0.466) in 30s. TC (r = 0.195), TG (r = 0.230), and diastolic blood pressure (r = 0.256) also correlated positively with age. In 10s group, significant positive correlations were found between IRI area and TC (r = 0.478), TG (r = 0.462), and LDL-C (r = 0.357). However, these correlations were not found in 20s and 30s groups. IRI area also correlated with systolic blood pressure only in 30s (r = 0.406). Correlations between IRI area and both systolic and diastolic blood pressure were weak and not significant among 10s and 20s groups. There was no change in S-fat between the three groups, but V-fat increased with age (r = 0.362). IRI area showed positive correlations with both V-fat and S-fat, but correlation was stronger with S-fat than with V-fat in every age group. In conclusion, various metabolic parameters including glucose and lipid profiles, blood pressure, and V-fat accumulation, showed deterioration with age. Although these metabolic disturbances were thought to be associated with insulin resistance and hyperinsulinemia, insulin secretion capacity among these subjects showed decline with age. This age-related discrepancy between insulin secretion and metabolic disturbances may be explained by 'thrifty phenotype' hypothesis: low protein intake in traditional Japanese diet may have imposed thrifty phenotype on the older group of these subjects, causing low insulin secretion capacity and impaired development of adipocyte precursor cells resulting preferential hypertrophic accumulation of intraabominal fat.

Original languageEnglish
Pages (from-to)67-76
Number of pages10
JournalBulletin of the Physical Fitness Research Institute
Issue number91
Publication statusPublished - 1996 Jan 1

Keywords

  • Adiposity rebound
  • Hyperinsulinemia
  • Syndrome X
  • Thrifty phenotype
  • Visceral fat

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Public Health, Environmental and Occupational Health
  • Physiology (medical)

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