When the blood sugar is too high, many people experience frequent urination and increased thirst, according to the American Diabetes Association. Other symptoms include a high reading when using a blood glucose meter and a high level of glucose in the urine.
As the blood sugar level increases, the individual is at risk for diabetic coma, according to Mayo Clinic. Before the coma, signs include fruity smelling breath, shortness of breath and fatigue. The patient often experiences a rapid heartbeat, nausea and fatigue. A diabetic coma is a medical emergency. When with a person who feels he may pass out from high blood sugar, it is essential to call the paramedics.
Glucose provides energy for the cells in the body. The endocrine system manages the levels of glucose in the blood by releasing insulin. Diabetics do not produce insulin or their bodies are unable to use the insulin they do produce, according to KidsHealth. This causes the blood sugar levels to increase, leading to serious health consequences.
Diabetics sometimes experience high blood sugar when their medication and food are not in balance. Other common causes of high blood sugar in these patients include infection, stress and illness, according to WebMD. While physical exercise usually lowers blood sugar levels, strenuous physical exercise when the insulin level is low increases blood glucose levels.