Fig. 1.

Model illustrating how physiological stress responses may be activated by loneliness (or by the absence of supporting relationships). Importantly, the sustained activation of physiological stress responses leads to changes in the cardiovascular system and cortisol production. This in turn may lead to increased food intake, in particular the intake of carbohydrates, and to increased insulin resistance. These processes play an important role in supplying the activated, metabolically demanding brain with sufficient glucose. Loneliness may also lead to depressive symptoms and/or sleep disturbances, which alter cortisol and glucose levels and increase the risk of type 2 diabetes. ^aThe following associations were tested: loneliness (exposure), depression and sleep (mediators) and type 2 diabetes (outcome). SAM, sympathetic adrenal medullary