Introduction
Mitochondria is a small compartment in every cell that produces the energy required for the cells. Mitochondrial disorders affect the functioning of mitochondria. It will make different signs and symptoms depending on the type of cells that got affected. When it affects the cells in the pancreas, diabetes can be a symptom. Diabetes mellitus is the most common endocrine disorder caused by mitochondrial diseases. A mutation in the mitochondrial or nuclear DNA causes mitochondrial disease. It can be transmitted hereditarily. The mitochondrial mutation is common and transmitted from the mother to the child. Mitochondrial encephalomyopathy, lactic acidosis, stroke-like episodes (MELAS), and maternally inherited diabetes and deafness (MIDD) are the common forms of mitochondrial diabetes caused by mutation of gene m.3243A>G.
What Are the Different Types of Diabetes?
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Type 1 Diabetes - Is an autoimmune type in which the immune system attacks the insulin-producing cells in the pancreas. It is usually present in children and young adults. 10% of the total diabetic people have type 1 diabetes.
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Type 2 Diabetes - Is the most common type of diabetes. In this type, the body does not produce enough insulin or cannot take up the available insulin (insulin resistance). Commonly affects adults more than children.
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Gestational Diabetes - During pregnancy, some people may develop diabetes. This is called gestational diabetes. It disappears after the delivery. Although, these people may develop type 2 diabetes later in their life.
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Type 3c Diabetes - When the pancreas is damaged by pancreatitis, pancreatic cancer, or cystic fibrosis, it will affect insulin production. Patients who have removed their pancreas also develop type 3c diabetes.
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Neonatal Diabetes - It is the type of diabetes present in a newborn baby. Either it disappears after a few months, or it continues to persist.
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Latent Autoimmune Diabetes in Adults (LADA) - It is also a form of autoimmune diabetes, but it usually starts after 30 years of age.
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Maturity Onset Diabetes of the Young (MODY) - It is a genetically inherited type of diabetes. It occurs due to a genetic mutation affecting insulin production and usage.
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Brittle Diabetes - It is a kind of type 1 diabetes with episodes of high and low glucose levels.
What Are the Causes of Mitochondrial Diabetes?
Mutations in the mitochondrial or nuclear DNA are the main causes of mitochondrial diseases. Diseases caused by these mutations are usually inherited from the mother to the child. Mitochondrial diabetes is caused by the mutation of gene m.3243A>G. This mutation affects the functions of insulin-producing cells in the pancreas and causes insulin resistance. Another cause that can trigger mitochondrial disease is environmental toxins.
What Are the Symptoms of Mitochondrial Diabetes?
Symptoms of mitochondrial diabetes are similar to that of type 1 and type 2 diabetes. They are as follows;
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Polyuria-increased urination.
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Increased thirst (polydipsia).
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Weight loss despite increased appetite.
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Nausea and vomiting.
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Blurred vision.
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Mood swings and irritability.
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Dehydration.
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High blood sugar levels.
Mitochondrial diabetes predominantly affects organs that require a high amount of energy to function, like the nervous system, kidneys, retina, muscles, and pancreas.
Clinical features of MELAS are episodes of stroke below the age of 40, seizures, dementia, vomiting, and recurrent headaches. Clinical features of MIDD include diabetes, deafness, muscle weakness, kidney disease, lactic acidosis, and retinal damage.
Another important clinical feature is superior mesenteric artery syndrome (SMAS). It is the compression of the duodenum (a part of the intestine) between the abdomen and the superior mesenteric artery. The symptoms include vomiting, loss of appetite, constipation, and difficulty in swallowing.
How Is Mitochondrial Diabetes Diagnosed?
Diabetes is diagnosed based on signs and symptoms along with blood and urine examination that shows high levels of sugar. Mitochondrial diseases are diagnosed with genetic testing. This involves analyzing a DNA sample from the affected individual to recognize any mitochondrial mutations.
A muscle biopsy is done in some cases to look for abnormalities in the mitochondria, such as ragged red fibers, which is an important sign in mitochondrial diseases. The sample is taken from the Vastus lateralis muscle (a muscle in the thigh). This is considered to be the gold standard in the diagnosis of mitochondrial diseases. Magnetic resonance imaging (MRI) is done to confirm neurological symptoms.
What Is the Treatment of Mitochondrial Diabetes?
There is no absolute cure for mitochondrial diabetes, so the treatment mainly focuses on managing the symptoms and complications associated with the condition. The primary goal is to maintain normal sugar levels to prevent kidney damage, nervous system damage, and vision problems. Usually, high sugar levels are treated with a medicine called Metformin, but in the case of mitochondrial diabetes, Metformin is contraindicated as it can cause lactic acidosis in patients.
In addition to managing blood glucose levels, treatment may also involve the management of muscle weakness, hearing loss, vision problems, and other neurological problems.
Other supportive treatment involves;
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Intravenous Arginine to reduce episodes of stroke.
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Folinic acid to treat neural damage.
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Gastric decompression in patients with superior mesenteric artery syndrome (SMAS).
Genetic counseling is also recommended for patients and their families affected by mitochondrial diabetes to help them understand the hereditary nature of the disease and make informed decisions about family planning. Females with mitochondrial diabetes can avoid transmitting the disease to the child by using “three-parent IVF.” It involves combining the father's sperm with a healthy ovum donor's mitochondria and cytoplasm and the nuclear DNA of the mother.
Conclusion
In a nutshell, mitochondrial diabetes is a rare and important disease. Individuals with mitochondrial diabetes, both children and adults, need regular monitoring of sugar levels and other symptoms need to be observed closely. As it is a genetic condition, it cannot be prevented. But with early diagnosis and proper management of the symptoms, the disease progression can be controlled.
