In addition to expression, GK activity has been observed in tanycytes (S0.5 of 10 mM)15. Thus, it is the presence of this functional isoform of GK, together with GLUT2, that makes it possible for tanycytes to sense and respond to glucose changes with increased intracellular calcium in a mechanism that involves GK activity3. The fact that GK knock-out mice die a few days after birth due to acute hyperglycemia highlights the vital role of GK16, 17. Millán et al.18 reported hypothalamic GK to be expressed mainly in α and β tanycytes; GK expression was weak in neurons and absent in astrocytes18. Similarly, Salgado et al.15 cloned GK expressed in tanycytes and demonstrated its functionality. However, there is enough information that validates its location in hypothalamic neurons19–22. Additionally, GLUT2 is expressed in hypothalamic tanycytes12. Interestingly, hypothalamic AN neurons do not express GLUT2; however, they are connected to nerve endings from GLUT2-expressing neurons23. On the other hand, GLUT2 is so well-located in the nucleus of solitary tract in neurons, and there is no evidence of glia expression in this brain region24. Recent evidence obtained after molecular and pharmacological activation of GK in rats cannulated into the AN shows that GK activity specifically regulates glucose intake and dietary glucose uptake25. Expression of glucokinase regulatory protein (GKRP), a known GK inhibitor with a critical metabolic role in hepatocytes26, has also been demonstrated in tanycytes15. The presence of GKRP in tanycytes reinforces the importance of GK activity in these cells.