Endocrine Abstracts

Background, subjects & methods: Visfatin, also known as pre-B cell colony enhancing factor (PBEF), is a cytokine that is highly expressed in visceral fat, and exerts insulin-mimicking effects in rodents through activation of an insulin receptor, though in a manner distinct from insulin. Visfatin levels do not change in response to acute hyperinsulinaemia in mice, but it is not clear whether this also applies to humans. In order to investigate this we measured serum visfatin, glucose and insulin concentrations during 75 gram oral glucose tolerance test (OGTT) in 17 subjects (2 males), age (mean±S.D.) 35.7±15.6 years, BMI 35.2±9.3 kg/m². Blood samples were taken before (0 minutes), and after 60 and 120 minutes after glucose administration.

Results: Two subjects were found to have impaired glucose tolerance and one subject was found to have diabetes mellitus. Glucose administration resulted in a highly significant increase in insulin (from 11.4±7.2 microU/ml at 0 min, to 98.9±68.6 microU/ml at 60 min and 72.6±45.1 microU/ml at 120 min of OGTT, P<0.001 for both 60 and 120 minutes in comparison to baseline). There was, however, no change in serum visfatin concentrations (84.6±11.6 ng/ml at 0 minutes, 82.6±12.7 ng/ml at 60 minutes and 81.1±14.5 ng/ml at 120 minutes of OGTT, P=ns).

Conclusions: There is a striking difference between the marked rise of insulin concentrations, and a lack of change in visfatin concentrations during oral glucose tolerance test. This implies, that it is highly unlikely that visfatin is involved in short-term regulation of glucose homeostasis in human subjects.