In patients with AVP deficiency, the median copeptin at baseline was 2.1 pmol/l [1.8–2.3] and increased only slightly after glucagon injection to 3.0 pmol/L [2.4–4.1], resulting in a median increase of 0.5 pmol/l [0.2–1.7]. Here, AVP is linked to neurohypophyseal diabetes insipidus.