LIPE and Impaired glucose tolerance: In fact, FFA is one of the key factors that influence insulin activity, and elevated FFA levels are predictive of the progression from impaired glucose tolerance to clinical diabetes.33 Insulin is a potent inhibitor of lipolysis and suppresses the release of FFAs from the adipocyte by inhibiting hormone-sensitive lipase.34 High levels of circulating FFAs, which can be found in obese individuals, are thought to cause IR in the fibers of skeletal muscles.