According to the United States National Center for Biotechnology Information, diabetes is a state in which a person has a high blood sugar level due to not having enough insulin because of pancreas disease(Type 1), or it may be because the body's cells do not respond to insulin(Type 2), or both. Type 1 usually occurs in children, while type 2 usually occurs in adults.  Sometimes women develop diabetes when they are pregnant, this is called gestational diabetes.  Over 20 million Americans have Type 2 Diabetes, and twice as many are at high risk for it. 

Symptoms of diabetes include increased thirst, increased hunger, and increased urination; as well as blurry vision, loss of sensation in the extremities, and fatigue.

The pancreas is innervated by Sympathetic and Parasymapthetic nerves.  The Celiac plexus is formed from the greater and lesser splanchnic nerves from T5-T11, as well as the right vagus nerve.  These nerves, as well as certain hormones, govern the function of the pancreas.

According to the American Journal of Physiology, sensory nerves play an important part in glucose tolerance, as was shown in the 2005 study, Sensory nerve inactivation by resiniferatoxin improves insulin sensitivity in male obese Zucker rats.  In the study, it was shown that by inactivating certain sensory nerves, the rats that had glucose insensitivity became more sensitive, thus reducing their blood sugar level as glucose was absorbed into the body's cells.

Some excerpts concerning Type 1 and possibly Type 2 Diabetes are below, from the science news site Science Daily:

ScienceDaily (Dec. 17, 2006) — Researchers at The Hospital for Sick Children (SickKids), the University of Calgary and The Jackson Laboratory, Bar Harbor, Maine have found that diabetes is controlled by abnormalities in the sensory nociceptor (pain-related) nerve endings in the pancreatic islet cells that produce insulin. This discovery, a breakthrough that has long been the elusive goal of diabetes research, has led to new treatment strategies for diabetes, achieving reversal of the disease without severe, toxic immunosuppression. This research is reported in the December 15 issue of the journal Cell.

According to Dr. Hans Michael Dosch, the study's pricipal investigator:
 ..."We started to look at nervous system elements that seemed to play a role in Type 1 diabetes and found that specific sensory neurons are critical for islet immune attack in the pancreas.... We are now working hard to extend our studies to patients, where many have sensory nerve abnormalities, but we don't yet know if these abnormalities start early in life and if they contribute to disease development."

As can be seen, nerves are are an important factor in the control of the pancreas, as well as in the tolerance of the body's cells in Diabetes.