Diagnosis
Besides the clinical picture, fasting VIP plasma level may confirm the diagnosis, and  CT scan and somatostatin receptor scintigraphy are used to localise the tumor, which is usually metastatic at presentation.Tests include:

Blood chemistry tests (basic or comprehensive metabolic panel)
CT scan of the abdomen
MRI of the abdomen
Stool examination for the cause of diarrhea and electrolyte levels
Vasoactive intestinal peptide (VIP) level in the blood

Treatment
The first goal of treatment is to correct dehydration. Fluids are often given through a vein (intravenous fluids) to replace fluids lost in diarrhea. The next goal is to slow the diarrhea. Some medications can help control diarrhea. Octreotide, which is a human-made form of the natural hormone somatostatin, blocks the action of VIP.The best chance for a cure is surgery to remove the tumor. If the tumor has not spread to other organs, surgery can often cure the condition.For metastatic disease, peptide receptor radionuclide therapy (PRRT) can be highly effective. This treatment involves attaching a radionuclide (Lutetium-177 or Yttrium-90) to a somatostatin analogue (octreotate or octreotide). This is a novel way to deliver high doses of beta radiation to kill tumours. Some people seem to respond to a combination chemo called capecitabine and temozolomide but there is no report that it totally cured people of VIPoma. Prognosis
Surgery can usually cure VIPomas. However, in one-third to one-half of patients, the tumor has spread by the time of diagnosis and cannot be cured. References

Jensen RT, Norton JA. Endocrine tumors of the pancreas and gastrointestinal tract. In: Feldman M, Friedman LS, Brandt LJ, eds.
Amino-acid substitution at position 8 prevents chemical breakdown by dipeptidyl peptidase-4. In addition, the lysine at position 26 is in its derivative form (acylated with stearic diacid). Acylation with a spacer and C-18 fatty diacid chain increases the drugs binding to blood protein (albumin), which enables longer presence in the blood circulation. History
Semaglutide was developed in 2012, by a team of researchers at Novo Nordisk as a longer-acting alternative to liraglutide as a once-weekly diabetes therapy. It was given the brand name Ozempic. Clinical trials were started on 6 January 2016, and completed on 19 May 2017.Researchers at the University of Leeds and Novo Nordisk reported in 2017, that it can also be used for the treatment of obesity. It reduces hunger, food craving and body fat. A phase 3 randomized controlled trial found that once-weekly injection of 2.4 mg of the drug resulted in an average change of −14.9% body weight at 68 weeks compared to −2.4% for the placebo.The US FDA New Drug Application (NDA) was filed in December 2016, and in October 2017, the FDA Advisory Committee approved it unanimously. It can be administered by injection or orally.