Insulin resistance is an intrinsic defect independent of fat mass in women with Turner's syndrome.
OBJECTIVE
Turner's syndrome (TS) is associated with increased insulin resistance and adiposity, which might be associated with type 2 diabetes in later life. We aimed to determine whether the defect in insulin sensitivity is a primary intrinsic defect in TS or dependent on variation in body composition.


METHODS
Sixteen women with TS not on growth hormone replacement but receiving oestrogen replacement therapy [age (mean +/- SD): 30.2 +/- 8.5 years; height-corrected fat-free mass: 26.1 +/- 3.1 kg/height] and a control group of 16 normal healthy women (age: 30.1 +/- 8.2 years; height-corrected fat-free mass: 25.9 +/- 2.4 kg/height) were studied. Fasting blood samples were obtained for measurement of glucose, insulin, IGF-I, IGFBP-1, IGFBP-3 and lipid levels. The hyperinsulinaemic euglycaemic clamp was performed to assess peripheral insulin sensitivity (M value), and the Homeostasis Model Assessment (HOMA-S) was used to estimate fasting insulin sensitivity. Body composition was assessed using a dual-energy X-ray absorptiometry scan.


RESULTS
Fasting insulin sensitivity (HOMA-S 103.2 +/- 78.6 vs. 193.9 +/- 93.5, p = 0.006) was lower in TS subjects compared to controls as was whole-body insulin sensitivity (M value 2.9 +/- 1.9 vs. 5.5 +/- 2.6 mg/kg/min, p = 0.003). In a multiple regression analysis the Turner karyotype was significantly related to insulin sensitivity (p = 0.008) independent of any differences in fat-free mass and percent whole-body fat mass.


CONCLUSIONS
The increased insulin resistance in women with TS is independent of measures of body composition and may represent an intrinsic defect related to their chromosomal abnormality.
Salgin
Burak
B
University Department of Paediatrics, University of Cambridge, Cambridge, UK.
Amin
Rakesh
R
Yuen
Kevin
K
Williams
Rachel M
RM
Murgatroyd
Peter
P
Dunger
David B
DB
D000293:Adolescent; D000328:Adult; D001823:Body Composition / Q000502:physiology*; D016022:Case-Control Studies; D002784:Cholesterol / Q000097:blood; D004967:Estrogens / Q000627:therapeutic use; D005215:Fasting / Q000097:blood; D005260:Female; D015309:Glucose Clamp Technique; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D008875:Middle Aged; D012044:Regression Analysis; D014424:Turner Syndrome / Q000188:drug therapy / Q000503:physiopathology*
D004967:Estrogens; D002784:Cholesterol