SLC6A4 and Glucose intolerance: Figure 3C and D show that insulin-induced clearance of blood glucose was compromised in 3- and 6-month old SERT−/− mice fed ND. SERT+/− mice also exhibited glucose intolerance and insulin intolerance, albeit the deficits at the age of 3 months were modest (Figure 3), showing that even a partial SERT deficiency may impair glucose homeostasis and insulin responses.