OBESITY, NON-INSULIN-DEPENDENT DIABETES-MELLITUS AND THE METABOLIC SYNDROME

Obesity is characterised by alterations in metabolic function which re sult from a combination of increasing total body fatness and the regio nal distribution of adipose tissue. Abdominal visceral obesity is part icularly associated with hyperinsulinaemia, increased portal vein free fatty acid concentration, hepatic gluconeogenesis, altered adrenocort ical activity and androgen secretion and reduced plasma sex hormone bi nding globulin levels. These alterations, which are accompanied by cha nges in visceral adipocyte sensitivity to plasma catecholamine stimula tion, enhance further visceral fat deposition and the perpetuation of the metabolic derangements. The characteristic dyslipidaemia associate d with upper body obesity and the Frequent development of NIDDM are pr edictable consequences. In contrast to the considerable knowledge abou t the biochemical background to these alterations, relatively little i s understood about the mechanisms through which an individual's ethnic background influences the changes. This chapter reviews these importa nt issues.