It is important to know that other medical problems can also cause a higher-than-normal blood glucose level, including:

• Overactive thyroid *

• Pancreatic cancer

• Pancreatitis or inflammation and swelling of the pancreas

• Stress due to trauma, stroke, heart attack, or surgery

• Rare tumors, and Cushing syndrome

• Hypoglycemia

• Hypopituitarism

• Under active thyroid gland, or adrenal gland

• Tumor in the pancreas 

• Too little food

• Too much insulin or other diabetes medicines

• Liver or kidney disease

• Weight loss after weight loss surgery

• Vigorous exercise

Some medicines can raise or lower your blood glucose level. Before having the test, tell your provider about all the medicines you are taking.

Note: For some people, mainly those who are thin and young, a fasting blood sugar level below 70 mg/dL (3.9 mmol/L) may be normal.

What causes high blood sugar?

A variety of things can trigger an increase in blood sugar level in people with diabetes, including

• Stress

• An illness such as a cold 

• Eating too much, such as snacking between meals

• A lack of exercise 

• Dehydration

• Missing a dose of your diabetes medication, or taking an incorrect dose

• An increase in how often you need to urinate

• Recently gained a lot of weight

• Blurred vision

• Confusion or a change in the way you normally talk or behave

• Fainting Spells

• Seizures(for the first time)

• Unconsciousness or coma