Measuring glucose control
In health, the blood glucose rarely strays outside a range of 3.5–7 mmol/l (65–125 mg/dl). If blood glucose falls below about 3.5 mmol/l (65 mg/dl), typical symptoms of hypoglycaemia appear, although these may diminish over time, causing difficulties in recognition (hypoglycaemia unawareness) and impaired central nervous system function; hypoglycaemia avoidance is therefore a prime aim of therapy. Glucose levels in excess of about 10 mmol/l lead to loss of glucose in the urine, leading to loss of salt and other electrolytes, excessive urine production and thirst. Uncontrolled glucose levels may progress to diabetic ketoacidosis if insulin is omitted or stress factors such as infection are encountered, but this is an avoidable condition. The risk of long-term harm to the cells lining larger arteries and small blood vessels increases in proportion to the level at which glucose exceeds the normal range, and treatment must aim to minimise this risk. It has further been shown that good glucose control in the early months and years of type 1 diabetes can prolong the life of remaining beta cell in the pancreas, which in turn makes longer term control easier to achieve.