In homeostatic regulation of blood glucose, the receptor and effector is the Pancreas, but how does the control centre — the Hypothalamus — connect and link into this process?
Your question doesn’t make it clear whether you think that the pancreas must be under the control of the hypothalmus, or whether you are asking whether it has an influence on the pancreas in relation to the secretion of insulin and glucagon, which control the concentration of blood glucose.
First, it has been long known that secretion of insulin can be influenced by the concentration of glucose in isolated pancreatic islets in vitro, so it can not be true that the effects must involve the hypothalmus. This is implicit in most book or general information articles you might find on the web, but for an original reference a review by W.J. Malaisse in Diabetologia 9, 167–173 (1973) seems highly cited.
I know almost nothing about physiology, but on searching the web for the role of the hypothalmus in glucose homeostasis, found a most readable prize-winning postgraduate essay on the topic by Syed Hussein of Imperial College London. I trust that it is in order to append an edited extract of this:
How does your brain control sugar?
…altered delivery of glucose to specific parts of the hypothalamus can change insulin, glucagon and glucose levels . …alterations in hormones and nutrient sensing by the brain in rodents leads to marked changes in glucose control. Evidence suggests that distinct regions of the brain have roles in controlling blood glucose in response to changes in glucose, insulin and fatty acids [ref]. These discrete brain nuclei regulate glucose output from the liver, insulin resistance, counter-regulatory responses to hypoglycaemia, glucose-stimulated insulin and glucagon release from the pancreas.
How does your brain tell the pancreas and liver what to do?
…blood glucose levels and hormones, such as insulin and glucagon, are influenced by the autonomic nervous system [ref]. This system …consists of two parts: a sympathetic nervous system which deals with ‘fight or flight’ responses such as stress and a parasympathetic nervous system which deals with ‘rest and digest’ and ‘feed and breed’ responses. This system arises in the brainstem of the brain and is under the control of the hypothalamus. Nerves from the autonomic nervous system innervate almost every organ in the body including the cells and blood vessels of the pancreas and liver. The ‘wandering’ vagal nerve, a key component of the parasympathetic nervous system, is shown to play an important role in this. This nerve is necessary for the brain to influence blood glucose. The autonomic nervous system can influence insulin release, glucagon release, liver glucose output and even the size and number of insulin producing cells in the pancreas [ref]. …Exactly how these nerve fibres regulate hormone release is still being slowly unravelled [ref].
The essay cites references which you may wish to follow up for further information.