Circulating IGF-I concentrations are low and not correlated to glycaemic control in adults with type 1 diabetes.
OBJECTIVE
To study plasma concentrations of insulin-like growth factor-I (IGF-I) in adults with type 1 diabetes (IDDM) in comparison with a reference population, and the influence of glycaemic control, dose of insulin, and sex on the concentration of circulating IGF-I in IDDM.


METHODS
Patients with type 1 diabetes were recruited consecutively from our outpatient diabetes unit. In all, 79 men and 55 women aged 20-60 years with a disease duration >/=6 years (range 6-51 years) took part in the study. A reference population of 80 men and 83 women aged 20-60 years was randomly obtained from the population registry. IGF-I was measured with radioimmunoassay after acid-ethanol extraction.


RESULTS
Mean +/- s. d. values of IGF-I were lower in patients with diabetes (146+/-66 microg/l) than in controls (238+/-83 microg/l, P<0.001). Those with diabetes had lower IGF-I concentrations in all age groups and the differences were highly significant in all decades except in women aged 50-59 years. IGF-I was negatively correlated with age in patients and controls. No correlation was found between IGF-I and glycaemic control measured as haemoglobin A(1c) (HbA(1c)) in the patients. IGF-I was positively associated with the dose of insulin/kg body weight in male patients independently of age, HbA(1c) and body mass index (P<0.03), but not in female patients (P=0.14).


CONCLUSIONS
Our data show that IGF-I concentrations are low in adult patients with type 1 diabetes with a disease duration >/=6 years, independently of glycaemic control. This suggests that subcutaneous insulin substitution is inadequate to normalize circulating IGF-I concentrations in patients without endogenous insulin secretion.
Ekman
B
B
Division of Internal Medicine, Department of Medicine and Care, Faculty of Health Sciences, Linköping University, Linköping, Sweden. Bertil.Ekman@lio.se
Nyström
F
F
Arnqvist
H J
HJ
D000328:Adult; D001786:Blood Glucose / Q000378:metabolism*; D015992:Body Mass Index; D003922:Diabetes Mellitus, Type 1 / Q000097:blood* / Q000188:drug therapy*; D005260:Female; D006442:Glycated Hemoglobin / Q000378:metabolism; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use; D007328:Insulin / Q000627:therapeutic use; D007334:Insulin-Like Growth Factor I / Q000032:analysis / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D012042:Registries; D012727:Sex Characteristics
D001786:Blood Glucose; D006442:Glycated Hemoglobin; D007004:Hypoglycemic Agents; D007328:Insulin; D007334:Insulin-Like Growth Factor I