title: Among overweight middle-aged men, first-borns have lower insulin sensitivity than second-borns.
abstract: We aimed to assess whether birth order affects metabolism and body composition in overweight middle-aged men. We studied 50 men aged 45.6 ± 5.5 years, who were overweight (BMI 27.5 ± 1.7 kg/m(2)) but otherwise healthy in Auckland, New Zealand. These included 26 first-borns and 24 second-borns. Insulin sensitivity was assessed by the Matsuda method from an oral glucose tolerance test. Other assessments included DXA-derived body composition, lipid profiles, 24-hour ambulatory blood pressure, and carotid intima-media thickness. First-born men were 6.9 kg heavier (p = 0.013) and had greater BMI (29.1 vs 27.5 kg/m(2); p = 0.004) than second-borns. Insulin sensitivity in first-born men was 33% lower than in second-borns (4.38 vs 6.51; p = 0.014), despite adjustment for fat mass. There were no significant differences in ambulatory blood pressure, lipid profile or carotid intima-media thickness between first- and second-borns. Thus, first-born adults may be at a greater risk of metabolic and cardiovascular diseases.
authors: Liggins Institute, University of Auckland, Auckland, New Zealand.
authors: Benjamin B
authors: BB
authors: Albert
authors: Liggins Institute, University of Auckland, Auckland, New Zealand.
authors: Martin
authors: M
authors: de Bock
authors: Liggins Institute, University of Auckland, Auckland, New Zealand.
authors: José G B
authors: JG
authors: Derraik
authors: Liggins Institute, University of Auckland, Auckland, New Zealand.
authors: Christine M
authors: CM
authors: Brennan
authors: Liggins Institute, University of Auckland, Auckland, New Zealand.
authors: Janene B
authors: JB
authors: Biggs
authors: 1] Liggins Institute, University of Auckland, Auckland, New Zealand [2] Gravida: National Centre for Growth and Development, University of Auckland, Auckland, New Zealand.
authors: Paul L
authors: PL
authors: Hofman
authors: 1] Liggins Institute, University of Auckland, Auckland, New Zealand [2] Gravida: National Centre for Growth and Development, University of Auckland, Auckland, New Zealand.
authors: Wayne S
authors: WS
authors: Cutfield
mesh_terms: D050154:Adiposity / Q000502:physiology; D000328:Adult; D001722:Birth Order; D001786:Blood Glucose / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology; D018660:Blood Pressure Monitoring, Ambulatory; D001823:Body Composition / Q000502:physiology*; D015992:Body Mass Index; D002318:Cardiovascular Diseases / Q000453:epidemiology; D059168:Carotid Intima-Media Thickness; D004734:Energy Metabolism / Q000502:physiology*; D005951:Glucose Tolerance Test; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009520:New Zealand / Q000453:epidemiology; D050177:Overweight / Q000453:epidemiology; D012307:Risk Factors
chemical_list: D001786:Blood Glucose