Type 1 and type 2 diabetes are chronic, life-long conditions that require careful monitoring and control. Without proper management they can lead to very high blood sugar levels which can result in long term damage to various organs and tissues.

 Cardiovascular disease: affects the heart and blood vessels and may cause fatal complications such as coronary heart disease (leading to heart attack) and stroke. Cardiovascular disease is the major cause of death in people with diabetes, accounting in most populations for 50% or more of all diabetes fatalities, and much disability.

 Kidney disease: can result in total kidney failure and the need for dialysis or kidney transplant. Diabetes is an increasingly important cause of renal failure, and indeed has now become the single most common cause of end stage renal disease, i.e. that which requires either dialysis or kidney transplantation, in the USA, and in other countries.

 Nerve disease: can ultimately lead to ulceration and amputation of the toes, feet and lower limbs. Loss of feeling is a particular risk because it can allow foot injuries to escape notice and treatment, leading to major infections and amputation.

 Eye disease: characterised by damage to the retina of the eye which can lead to loss of vision.

 Women with gestational diabetes may have children who are large for their gestational age.