There are different types of diabetes. The major types are referred to as type 1, type 2 and gestational diabetes mellitus (diabetes during pregnancy).
Type 1 Diabetes Mellitus
Type 1 diabetes mellitus affects most commonly children and teenagers and is due to defective insulin production as a result of the destruction of insulin-producing cells (beta cells) in the pancreas. It is not totally clear what causes the destruction of beta cells but there is an abundance of evidence indicating autoimmune factors to be of importance. Also, a strong hereditary pattern with a doubling of the risk in identical twins has been identified. Patients with Type 1 Diabetes are in need of several injections of insulin every day.
Type 2 Diabetes Mellitus
Type 2 Diabetes affects mostly adults and constitutes around 90% of all cases of diabetes in the world. Type 2 Diabetes is caused by insufficient production of insulin in the pancreas and a resistance to the action of insulin in the body's cells - especially in muscle, fat and liver cells. Exactly why this happens is unknown, although heredity and lifestyle factors such as excess weight and inactivity seem to be contributing factors. A high calorie intake and physical inactivity requires higher insulin production to regulate blood sugar. When beta cells cannot respond to these demands, the blood sugar levels rise. This process occurs gradually and the symptoms are less noticeable, which is the reason why the disease may be diagnosed several years after the initial onset. In many cases, there are already established complications when the diagnosis occurs.
Type 2 Diabetes is often associated with other diseases such as hypertension (high blood pressure) and hyperlipidemia (high levels of cholesterol in the blood) increasing the risk of coronary heart disease. Nowadays, this type of diabetes is being diagnosed in obese children due to a contemporary lifestyle that includes excessive calorie intake and the lack of physical activity.
LADA (Late Onset Autoimmune Diabetes in Adults) affects primarily individuals over the age of 35 years. In these patients usually there is no need for insulin treatment during the first six months after diagnosis but the insulin levels tend to drop with time and there will eventually be a need for treatment with insulin injections.
Diabetes developed or diagnosed during pregnancy is called gestational diabetes. It is estimated that about 2-5% of pregnant women develop gestational diabetes but the figures seem to be much higher in the Middle East countries. Gestational diabetes is more common in overweight women and women with a family history of diabetes. Due to weight gain and effects of hormones during pregnancy, there is an increase in insulin resistance causing a greater need of insulin. If the insulin producing cells in the pancreas cannot compensate for this need, then diabetes develops. Even if the condition resolves after delivery in most cases, women with gestational diabetes have a greater risk of developing diabetes later in life (around 50% develop diabetes within 5 years after childbirth).
In most cases, gestational diabetes causes no symptoms in the mother and poses no immediate threat to her health. However, it poses some real risks for the baby. If gestational diabetes goes undetected, the baby has an increased risk of stillbirth or death as a newborn. The major risk for babies of women with gestational diabetes is macrosomia (excessive weight at birth). Both the likelihood of caesarean birth and the risk of birth injuries are increased when the baby is macrosomic. Keeping the glucose level of a mother who has gestational diabetes within the normal range is thought to decrease this risk. Other problems that may develop as a result of gestational diabetes include hypoglycaemia (low blood sugar) in the baby shortly after birth. This may occur because the baby has been accustomed to receiving high levels of blood sugar across the placenta, and the supply is abruptly stopped when the umbilical cord is cut at birth.
Other forms of Diabetes
There are other forms of diabetes which are very rare and explain only a few percent of the diabetes cases. These forms can depend on gene mutations and in recent years, several risk genes have been identified.