Diabetes – a non-communicable epidemic
Diabetes mellitus is one of the major common diseases that represent an increasing challenge for the western industrial nations. Due to the increasingly high incidence of the disease, in 2006 the United Nations declared diabetes mellitus to be a global health threat and accorded it epidemic status as first non-infectious disease.
Diabetes is a collective term for diseases of the glucose metabolism characterized by loss of production or effect of the hormone insulin. The precise pathomechanisms of the disease have not yet been elucidated. It is known, however, that a combination of genetic and lifestyle factors leads to diabetes. In Germany alone, eight million people currently suffer from this disease – that is almost 10% of the population, and the number of unreported cases is probably just as high.
Type1 Diabetes mellitus
In type 1 diabetes, the insulin-producing cells in the islets of Langerhans are destroyed. The subsequent insulin deficiency leads to metabolic disturbances in the body. Typical changes in blood and urine include hyperglycemia (elevated blood glucose levels), hyperlipidemia (elevated blood lipid levels), glucosuria (increased excretion of glucose in the urine) and ketoacidosis (acidification of the blood due to accumulation of ketone bodies).
Clinically, type 1 diabetes manifests itself in increased urination, weight loss, muscle weakness, exhaustion, fatigue and severe thirst. Poor blood sugar control also promotes secondary diseases such as kidney, nerve and eye damage, and atherosclerotic changes in the blood vessels.
How high is the incidence of type 1 diabetes?
Overall, 0.4 percent of the population in Germany has type 1 diabetes; half of them are diagnosed with the disease when they are under 20 years of age. In contrast to type 2 diabetes, commonly known as adult-onset diabetes, type 1 diabetes primarily develops in childhood and adolescence.
As in Type-2-Diabetes, the incidence rates of type 1 diabetes have increased dramatically in recent years. To date, the reasons for this increase are not completely understood.
Type 2 Diabetes mellitus
Most diabetes patients have type 2 diabetes. Decreased sensitivity to the hormone insulin is characteristic for the development of type 2 diabetes – the body’s need for insulin rises sharply. This status is termed pre-diabetes, a precursor stage of type 2 diabetes. When the pancreas is no longer able to accommodate the body’s increased need for insulin, type 2 diabetes becomes clinically manifest. Antidiabetic medications and insulin therapy – the therapies available to date – alleviate the symptoms but do not fight the cause of diabetes.
A precise understanding of the mechanisms responsible for the development of the disease is still lacking. Advances in life sciences and modern technologies now facilitate new methods and research approaches to better understand metabolism and metabolic disorders.
How common is type 2 diabetes?
Diabetes mellitus is the most common metabolic disorder in the western industrial nations. According to statistics of the International Diabetes Federation (IDF) from 2007, there are approximately 246 million diabetics worldwide. Experts anticipate that by the year 2025 this number will increase to about 380 million people. In Germany there are currently around eight million known cases of diabetes. In reality, there are probably far more because many people are unaware that they have the disease. A realistic number in the group of the adult population is probably around 50 percent. About 90 percent of all diabetes patients have Type-2-Diabetes; over half are over 65 years old.
What is gestational diabetes?
Gestational diabetes is one of the most common complications during pregnancy. Women who have gestational diabetes are at increased risk of developing Type-2-Diabetes, even years to decades after giving birth. Moreover, the child’s risk of becoming overweight or diabetic is also affected by the mother’s gestational diabetes.
By definition, gestational diabetes (GDM) means any glucose tolerance disorder which is diagnosed during pregnancy for the first time. In principle, the term also includes newly discovered forms of Type-1- and Type-2-Diabetes but in practice it is usually a temporary Type-2-Diabetes, which can result in a manifest Type-2-Diabetes several years after giving birth. Because of its close association to Type-2-Diabetes, gestational diabetes is regarded as one of its precursors. In general, the metabolic complication has few symptoms; the typical signs of diabetes mellitus such as excessive thirst and increased urination are usually absent. However, if it remains untreated it bears risks both for the birth process and for the child.
How is gestational diabetes different from preconceptional diabetes?
A Type -1 or Type-2-Diabetes which is diagnosed prior to a pregnancy is not considered to be gestational diabetes. However, so-called preconception diabetes increases the risk for the child to become overweight or diabetic just as markedly as gestational diabetes. As with the impaired glucose tolerance that occurs only during pregnancy, poorly controlled blood glucose levels can increase blood glucose levels of the fetus (fetal hyperglycemia) and lead to elevated insulin levels in the amniotic fluid. The possible consequence is a programming error in the weight and metabolic regulation of the child.
However, the mother’s Type-1-Diabetes as such does not increase the child’s risk to become overweight; other contributing factors associated with the disease increase this risk. This is shown in the results of the BABYDIAB study conducted by the Institute of Diabetes Research at Helmholtz Zentrums München and the Forschergruppe Diabetes of Technische Universität München. For example, children of mothers with Type-1-Diabetes tend to have a higher birth weight than children of healthy mothers. Moreover, these babies are also breast-fed less frequently. Both factors increase the risk of children becoming overweight later, regardless of the diabetes of the mother. In the BABYDIAB study Munich researchers are investigating around 1,600 children and young adults with a positive family history of Type-1-Diabetes.
What are the risks for the child?
Various studies suggest that diabetes during pregnancy increases the risk of children becoming overweight in later life and developing Type-2-Diabetes. Fetal hyperinsulinism, elevated insulin levels in amniotic fluid, plays a key role here. Thus, in children of diabetic mothers with fetal hyperinsulinism, the risk of developing impaired glucose tolerance is three-and-a-half times higher than in children of diabetic mothers with normal fetal insulin levels. Experts speak of "intrauterine programming" in this context. This term refers to a process from the 28th week of pregnancy until the end of the first week of life, in which factors such as diet and hormones characterize the future function of organs and organ systems permanently. Fetal insulin secretion, for example, lays down the set point for the regulation of insulin secretion after birth.
What are the risks for the mother?
For the affected women, diabetes in pregnancy can have serious consequences. Although the metabolic disorder usually disappears after the birth of the child, many of these women develop Type-2-Diabetes later in life. This has been shown by a German Gestational Diabetes Study conducted by researchers at the Institute of Diabetes Research at Helmholtz Zentrum München and the Forschergruppe Diabetes of Technische Universität München.
Autoantibodies to GAD (glutamic acid decarboxylase), a typical sign of Type-1-Diabetes, were found in only about ten percent of the study participants. According to the German Gestational Diabetes Study, the women who are particularly at risk for developing diabetes after pregnancy are those who have to inject insulin during pregnancy, who have a BMI of more than 30 kg/m2 and who have had two previous pregnancies.