Thiazides are used to treat type 2 diabetes but it also causes severe hyperglycemia. Stress
A high proportion of patients with an acute stress such as stroke or myocardial infarction may develop hyperglycemia, even in the absence of a diagnosis of diabetes. (Or perhaps stroke or myocardial infarction was caused by hyperglycemia and undiagnosed diabetes.) Human and animal studies suggest that this is not benign, and that stress-induced hyperglycemia is associated with a high risk of mortality after both stroke and myocardial infarction. Somatostatinomas and aldosteronoma-induced hypokalemia can cause hyperglycemia but usually disappears after the removal of the tumour.Stress causes hyperglycaemia via several mechanisms, including through metabolic and hormonal changes, and via increased proinflammatory cytokines that interrupt carbohydrate metabolism, leading to excessive glucose production and reduced uptake in tissues, can cause hyperglycemia.Hormones such as the growth hormone, glucagon, cortisol and catecholamines, can cause hyperglycemia when they are present in the body in excess amounts. Diagnosis
Monitoring
It is critical for patients who monitor glucose levels at home to be aware of which units of measurement their glucose meter uses. Glucose levels are measured in either:
Millimoles per liter (mmol/L) is the SI standard unit used in most countries around the world. Milligrams per deciliter (mg/dL) is used in some countries such as the United States, Japan, France, Egypt and Colombia.Scientific journals are moving towards using mmol/L; some journals now use mmol/L as the primary unit but quote mg/dL in parentheses.Glucose levels vary before and after meals, and at various times of day; the definition of "normal" varies among medical professionals.
Causes
Hyperglycemia may be caused by: diabetes, various (non-diabetic) endocrine disorders (insulin resistance and thyroid, adrenal, pancreatic, and pituitary disorders), sepsis and certain infections, intracranial diseases (e.g. encephalitis, brain tumors (especially if near the pituitary gland), brain haemorrhages, and meningitis) (frequently overlooked), convulsions, end-stage terminal disease, prolonged/major surgeries, excessive eating, severe stress, and physical trauma. Endocrine
Chronic, persistent hyperglycaemia is most often a result of diabetes. Several hormones act to increase blood glucose levels and may thus cause hyperglycaemia when present in excess, including: cortisol, catecholamines, growth hormone, glucagon, and thyroid hormones. Hyperglycaemia may thus be seen in: Cushings syndrome, pheochromocytoma, acromegaly, hyperglucagonemia, and hyperthyroidism. Diabetes mellitus
Chronic hyperglycemia that persists even in fasting states is most commonly caused by diabetes mellitus. In fact, chronic hyperglycemia is the defining characteristic of the disease. Intermittent hyperglycemia may be present in prediabetic states. Acute episodes of hyperglycemia without an obvious cause may indicate developing diabetes or a predisposition to the disorder.In diabetes mellitus, hyperglycemia is usually caused by low insulin levels (diabetes mellitus type 1) and/or by resistance to insulin at the cellular level (diabetes mellitus type 2), depending on the type and state of the disease. Low insulin levels and/or insulin resistance prevent the body from converting glucose into glycogen (a starch-like source of energy stored mostly in the liver), which in turn makes it difficult or impossible to remove excess glucose from the blood.