What is diabetes?
Diabetes is a condition where blood sugar levels (glucose) are too high and difficult to control. Insulin, produced by the pancreas, is the main blood glucose regulating hormone. It ensures that there is enough glucose needed for energy throughout the body, particularly the brain. Glucose is produced in the liver and also absorbed from the diet. Excess glucose is stored in the liver and muscles. Hyperglycaemia is when too much glucose circulates in the blood, either because your body does not make enough insulin or has become resistant to the effects of insulin.
Diabetes exists in two forms. Type 1 diabetes is usually hereditary, develops early in life, and is caused by damage to the pancreas due to attack by the body’s immune system. Type 2 diabetes usually begins later in life and is related to lifestyle factors, including obesity, poor diet, smoking, and lack of exercise.
Diabetes increases the risk of serious health complications caused by damage to blood vessels. Damage to large blood vessels like arteries (macrovascular) can cause cardiovascular disease resulting in heart attack and stroke. Damage to small blood vessels like capillaries (microvascular) can cause kidney failure (diabetic nephropathy), and eye damage with loss of vision (diabetic retinopathy). Damage to nerves (diabetic neuropathy) can result in amputation, particularly of the toes.
How do diabetic medications work?
Diabetic medications that are taken as tablets are known as oral antihyperglycaemics and are classed according to how they work. They should be used alongside improving diet and increasing exercise and they include:
- Biguanides like metformin improve your body’s response to the effects of insulin, increase the amount of glucose that is stored, and reduce the amount of glucose produced in the liver and absorbed from the diet.
- Acarbose inhibits the action of the enzyme alpha-glucosidase that converts carbohydrates in the diet to simple sugars like glucose, and this reduces the amount of glucose that enters the blood after a meal.
- Thiazolidinediones like rosiglitazone and pioglitazone reduce insulin resistance by increasing the body’s response to insulin and acting directly on cells of the liver, muscle, and fat tissue.
- Sulphonylureas like glipizide increase insulin production by directly stimulating the pancreatic beta cells to produce more insulin.
- Gliflozins like empagliflozin and canagliflozin act directly on the kidneys to inhibit glucose reabsorption from the urine back into the blood, to lower blood glucose levels.
- DPP-4 inhibitors like sitagliptin work by inhibiting the enzyme dipeptidyl peptidase 4 (DPP-4) and preventing the destruction of incretins, which are small proteins released from the intestine after a meal that stimulate insulin production and reduce glucose production by the liver.