Endocrine / Nervous System Based on Tanya's symptoms, and especially her out of shape condition, she is presumably showing signs of Type 2 Diabetes Mellitus, or insulin-resistant diabetes. Tanya is unlikely to have Type 1, an autoimmune condition in which the insulin-producing cells in the pancreas are killed off, as this manifests itself predominantly in children. While Type 1 can appear in an adult, Type 2 is very frequently caused by poor dietary and exercise habits like Tanya exhibits.

Tanya's blood has a high level of sugar (hyerglycemia) but her cells are starved of sugar. This is due to the mechanics of Type 2 Diabetes, in which the body produces the hormone insulin -- which is responsible for the regulation of delivering glucose as fuel for cells (such as muscle or fat cells, which cannot absorb glucose without the action of insulin) -- but the cells themselves become resistant to the presence of the insulin, and thus fail to absorb the glucose. As a result, the glucose levels in the blood mount. Ordinarily the liver is responsible for slowing down the release of glucose in hyperglycemic conditions, however the liver's cue to begin this process is the absence of insulin: because insulin-resistant diabetics have plenty of insulin (which simply does not function properly)...

The chief unmentioned symptom that probably affects Tanya's increased thirst is a frequent urination. The hyperglycemia of diabetic patients causes them to excrete excess glucose through urine. Ahmed (2002) in his historical survey of the disease notes that the formal name "diabetes mellitus," literally means "honey-sweet" and was added to the disease name in the seventeenth century by Thomas Willis, in recognition of the excess of glucose in the urine and blood of diabetics, which causes both to taste sweet (373).
4. Like insulin, glucagon is a hormone produced by the pancreas and is involved in the regulation of blood sugar. Glucagon is basically the opposite of insulin: it causes an increased release of glucose into the blood, while insulin ordinarily lowers blood glucose levels by promoting absorbption by the cells. The difficulty here is that any drug that would block the action of glucagon in Type 2 diabetes would essentially be causing the cells to become just as insensitive to glucagon as they already are to insulin. To a certain degree, this could make blood sugar levels altogether harder to regulate. Although glucagon-receptor antagonists remain a line of research…