Increased systemic and adipose tissue inflammation differentiates obese women with T2DM from obese women with normal glucose tolerance.

Introduction: Obesity is strongly related to type-2 diabetes (T2DM), but there is a subset of obese individuals that remains relatively insulin sensitive and metabolically healthy. This study determined to what extent differences in metabolic health in obese women are associated with differences in adipose tissue and/or systemic inflammation.

Methods: The subject group consisted of age comparable lean (n=12) and obese women either with T2DM (n=28) or normal glucose tolerance (NGT; n=26). Number of crown like structures (CLS) and adipocyte size were measured in subcutaneous and visceral adipose tissue of the obese women. Circulating cytokine and free fatty acid (FFA) levels, as well as number and activation status of peripheral leukocytes were determined.

Results: Obese T2DM subjects showed higher circulating levels of IL-6, FFA and glycerol as compared to obese NGT subjects. Obese T2DM subjects had higher absolute numbers of peripheral leukocytes which were mainly due to an increase of T helper cells. Activation status of circulating cytotoxic T (CD8+CD25+) and B (CD19+CD38+) cells was significantly increased in obese NGT subjects as compared to lean but was not different between the two obese groups. Subcutaneous adipose tissue of obese T2DM subjects contained more CLS than adipose tissue of obese NGT subjects.

Conclusion: Obese T2DM subjects show higher FFA levels and adipose tissue macrophage infiltration in addition to higher levels of circulating IL-6 and numbers of CD4+ T cells than obese NGT subjects. Hence, obese T2DM subjects show a higher extent of inflammation at both the systemic and adipose tissue level.