Human adipose tissue glycogen levels and responses to carbohydrate feeding

Glycogen has long been known to be present in adipose tissue, but its role is not clear. It has not been measured in human adipose tissue. We have investigated methods for its measurement using rat adipose tissue, and measured levels in humans. Glycogen in rat adipose tissue was found to be labile, necessitating rapid sample preservation. Levels in random biopsies of human adipose tissue were variable, but consistent with values for other species (0.06-0.78 mg/g wet weight; n = 5). After overnight fast, consistent low levels were found (0.04-0.08 mg/g wet weight; n = 6); these increased after eating a high-carbohydrate diet (800 g/d for 2.5 d), to 0.10-1.95 mg/g wet weight (P less than 0.05). Human adipose tissue glycogen appears to play a minor role in whole-body glucose homeostasis, but may have an important local role in the regulation of lipogenesis.