Does brown adipose tissue have a role to play in glucose homeostasis?

Obesity and type I1 diabetes co-exist within the same population and the term 'diabesity' has been coined to cover this vast group of patients.First-line therapy is a prudent low-fat, high-fibre diet together with an increase in the level of exercise.This therapy is designed to restore body-weight to normal and improve the insulin sensitivity of peripheral tissues, particularly muscle.James & Trayhurn (1976) developed the hypothesis that energy expenditure on regulatory non-shivering thermogenesis made a significant contribution to overall energy expenditure, and variations in this component might be important in explaining the variable propensity to obesity in both man and animals.Since then, in a range of animals including oblob mice, dbldb mice, falfa rats and mice given gold thioglucose, the co-existence of insulin resistance and obesity has been demonstrated.In each case, evidence has been obtained of early changes in both variables, before overt obesity.Another example of this correlation is the rat fed on a cafeteria-type diet.Rothwell & Stock (1982Stock ( ,1983) demonstrated that obesity is resisted in young rats but not in old rats.As shown in Table 1, young rats fed on a cafeteria diet show enhanced insulin sensitivity, as measured by the glucose disposal rate following intravenous administration of insulin, whereas old rats are insulin resistant.In human studies, Golay et al. (1986) found a correlation in a range of subjects between thermic response to a 100 g oral glucose load and insulin-mediated glucose uptake under euglycaemic-clamp conditions. Old Cafeteria2.75* 0.93