Monogenic diabetes

Definition

Some rare forms of diabetes result from mutations or changes in a single gene and are called monogenic.

Sometimes the gene mutation develops spontaneously, meaning that the mutation is not carried by either of the parents. Most mutations that cause monogenic diabetes reduce the body’s ability to produce insulin, a protein produced in the pancreas that helps the body use glucose for energy.

polygenic forms

• The most common forms of diabetes, type 1 and type 2, are polygenic, meaning they are related to a change, or defect, in multiple genes. Environmental factors, such as obesity in the case of type 2 diabetes, also play a part in the development of polygenic forms of diabetes.
• Polygenic forms of diabetes often run in families. Doctors diagnose polygenic forms of diabetes by testing blood glucose, also known as blood sugar, in individuals with risk factors or symptoms of diabetes.
• Genes provide the instructions for making proteins within the cell. If a gene has a change or mutation, the protein may not function properly. Genetic mutations that cause diabetes affect proteins that play a role in the ability of the body to produce insulin or in the ability of insulin to lower blood glucose. People typically have two copies of most genes, with one gene inherited from each parent.

Forms

Neonatal diabetes mellitus (NDM) and maturity-onset diabetes of the young (MODY) are the two main forms of monogenic diabetes. NDM occurs in newborns and young infants. MODY is much more common than NDM and usually first occurs in adolescence or early adulthood.

Signs and symptoms

Neonatal diabetes mellitus (NDM):

• NDM is a monogenic form of diabetes that occurs in the first 6 to 12 months of life.
• Clinical features of NDM depend on the gene mutations a person has. Signs of NDM include frequent urination, rapid breathing, and dehydration. NDM can be diagnosed by finding elevated levels of glucose in blood or urine. The lack of insulin may cause the body to produce chemicals called ketones, resulting in a potentially life-threatening condition called diabetic ketoacidosis.
• Most fetuses with NDM do not grow well in the womb, and newborns with NDM are much smaller than those of the same gestational age, a condition called intrauterine growth restriction. After birth, some infants fail to gain weight and grow as rapidly as other infants of the same age and sex. Appropriate therapy may improve and normalize growth and development.

Maturity onset diabetes of the young (MODY):

• MODY is a monogenic form of diabetes that usually first occurs during adolescence or early adulthood.
• Clinical features of MODY depend on the gene mutations a person has. People with certain types of mutations may have slightly high blood sugar levels that remain stable throughout life, have mild or no symptoms of diabetes, and do not develop any long-term complications. Their high blood glucose levels may only be discovered during routine blood tests. However, other mutations require specific treatment with either insulin or a type of oral diabetes medication called sulfonylureas.

Diagnosis

Genetic testing can diagnose most forms of monogenic diabetes. A correct diagnosis with proper treatment should lead to better glucose control and improved health in the long term.

Genetic testing is recommended if:

• diabetes is diagnosed within the first 6 months of age
• diabetes is diagnosed in children and young adults, particularly those with a strong family history of diabetes, who do not have typical features of type 1 or type 2 diabetes, such as the presence of diabetes-related autoantibodies, obesity, and other metabolic features
• a person has stable, mild fasting hyperglycemia, especially if obesity is not present

Treatment

• Treatment varies depending on the specific genetic mutation that has caused a person’s monogenic diabetes. People with certain forms of MODY and NDM can be treated with a sulfonylurea, an oral diabetes medicine that helps the body release more insulin into the blood. Other people may need insulin injections.
• Some people with MODY may not need medications and are able to manage their diabetes with lifestyle changes alone, which include physical activity and healthy food choices. Your physician and diabetes care team will work with you to develop a plan to treat and manage your diabetes based on the results of genetic testing.

NIH genetic and rare disease info

• NIH info on Monogenic diabetes

Monogenic diabetes is a rare disease.

Monogenic diabetes Resources
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