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Maturity-onset diabetes of the young (MODY) is an inherited form of diabetes. It does not fit into the traditional definitions of either type 1 diabetes or type 2 diabetes classifications but can often be misdiagnosed as either.
Confusion continues over the classification of MODY. For example, the U.S. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) and the American Diabetes Association (ADA) have both issued some materials describing MODY as a form of type 2 diabetes and other materials describing MODY as distinct from type 2. It is sometimes classified as a form of secondary diabetes.
MODY is sometimes referred to as type 1.5 diabetes. However, that term has also been used to describe other conditions including latent autoimmune diabetes of adulthood (LADA) and double diabetes.
MODY has four main characteristics:
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It develops at an early age, typically before age 25.
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MODY appears in families throughout several generations. Children have a 50 percent chance of developing MODY if a parent has the condition.
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A patient diagnosed with MODY rarely needs insulin treatment and can frequently manage the disease through diet or antidiabetic medications.
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MODY is different from type 1 and type 2 diabetes. In type 2 diabetes, patients produce insulin but their bodies do not respond to it properly. This insulin resistance is not seen in MODY. In addition, people with type 2 diabetes are often overweight and over 40 years of age, whereas MODY tends to develop much earlier, and patients generally have a thin build.
Patients with MODY do not produce enough insulin to meet their body’s needs. However, unlike people with type 1 diabetes whose bodies stop producing insulin, MODY does not involve an autoimmune response or usually require insulin administration.
| MODY |
Type 1 |
Type 2 |
| Accounts for about 1 to 5 percent of diabetes cases |
5 to 10 percent of diabetes cases |
Accounts for 90 to 95 percent of diabetes cases |
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Inherited – a parent with MODY has a 50 percent chance of passing it to a child
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Autoimmune disorder damages the pancreas |
Cause unknown, but risk factors include age, obesity, genetics and lifestyle |
| Problem with insulin secretion, not insulin resistance |
Pancreas makes little or no insulin |
Often an excess of insulin, but body cannot use it properly |
| Most often begins in teens and early 20s |
Most often develops in childhood or adolescence |
Most often begins in adulthood (after age 40) |
| Patients generally of thin or normal build |
Patients generally of thin or normal build |
Patients generally overweight or obese |
| Treated primarily with diet and antidiabetic agents; some forms require insulin therapy |
Treated primarily with insulin therapy |
Treated primarily with exercise, diet, antidiabetic agents and sometimes insulin |
| Often experience marked hyperglycemia |
Severe and rapid onset, generally |
Often develops slowly, sometimes undetected for many years |
With MODY, the main problem is an insulin secretion defect. When the pancreas fails to produce adequate amounts of insulin, problems develop in the transportation of glucose into cells. As a result, hyperglycemia can develop, which in turn, can lead to the body becoming resistant to insulin. With MODY, the inadequate secretion of insulin can resemble type 1 diabetes.
Though type 1 diabetes also involves damage to the pancreas, there is one distinct difference between the process in type 1 diabetes and MODY: time. In MODY, this process is slow to unfold and reduces rather than destroys the pancreas’ ability to secrete insulin. Instead, MODY impairs the secretion of insulin in such a way that the body is unable to control blood glucose levels.
This uncommon form of diabetes appears to be caused solely by genetics, as a single–gene mutation. The gene defect primarily affects the function of insulin-producing beta cells, causing the development of this disease. MODY is an autosomal dominant disease, meaning only one parent needs to have the abnormal gene for a child to inherit it.
MODY accounts for less than 5 percent of those diagnosed with diabetes, according to the ADA. In most cases, MODY occurs in several generations of a family and often develops in the teen years or early 20s.
More than 25 years ago, the U.S. National Diabetes Data Group (NDDG) and the World Health Organization (WHO) had recognized the two major types of diabetes. The first was called insulin-dependent diabetes mellitus, now known as type 1 diabetes, and the other was termed non-insulin-dependent diabetes, now known as type 2.
However, some physicians were beginning to notice a small group of young people (usually younger than 25 years of age and of normal weight) who had been diagnosed with diabetes but had been successfully treated without insulin for two years or more. These physicians were among the first to realize that there were other types of diabetes that did not fit the typical profiles of either type 1 or type 2 diabetes. The prime example is MODY.
For nearly a decade, researchers have known about two genes (PDX-1 and neuro-D1) and their role in generating insulin production in the beta cells of the pancreas. The absence of either of these two genes is believed to be partially responsible for MODY. However, additional research is under way to determine the exact trigger in the development of this form of diabetes.
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