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In addition to the most well-known types of diabetes, type 1 and type 2, there are also several other distinct varieties. All forms of diabetes are characterized by high blood glucose levels, but these lesser-known subclasses have distinct underlying disease pathologies and are less frequently observed in the general population.
Here are some of the other medically recognized forms of diabetes:
- Gestational Diabetes
- Latent Autoimmune Diabetes in Adults (LADA)
- Maturity-Onset Diabetes in the Young (MODY)
- Secondary Diabetes
This article focuses on summarizing the underlying causes and available treatments for these forms of diabetes.
Diabetes Overview
When the media talks about diabetes, they’re usually talking about type 2. Type 2 diabetes accounts for over 90 percent of all diabetes cases and primarily affects adults. The diagnosis and progression of type 2 diabetes are closely associated with family history and lifestyle factors, including diet, sedentary habits, and excess weight. Patients with type 2 diabetes will often have varying degrees of insulin production and insulin resistance. They are universally recommended lifestyle modifications, like healthier diet and exercise, and usually take medications, including oral drugs like metformin, injectable drugs like semaglutide (Ozempic), insulin, or a combination of these.
In contrast, type 1 diabetes is an autoimmune condition that results in the destruction of insulin-secreting cells in the pancreas, and accounts for only about two or three percent of diabetes cases worldwide, according to the World Health Organization. The causes of type 1 diabetes involve both genetic and environmental factors, but are ultimately mysterious. Patients with type 1 diabetes must regularly administer medicinal insulin to survive.
The forms of diabetes discussed below can share features with both type 1 and type 2 diabetes. In every case, some type of metabolic dysfunction results in hyperglycemia, but the details differ.
Gestational Diabetes
Gestational diabetes is defined by increased insulin resistance during pregnancy, leading to high blood sugar levels. The condition is often unsymptomatic and is usually caught by routine testing. Untreated gestational diabetes can lead to adverse complications for both mother and child.
Most often, gestational diabetes resolves after pregnancy, although women who experience gestational diabetes are more likely to experience it again in a future pregnancy, and researchers estimate that as many as 50 percent of women with gestational diabetes may develop type 2 diabetes.
Experts believe that hormonal changes, especially in the second half of pregnancy, are responsible for gestational diabetes. While all women experience increased insulin resistance in pregnancy, the pancreas is usually able to adjust by producing extra insulin, enough to keep blood glucose levels in the normal range. When the pancreas cannot produce enough insulin, rising blood sugars lead to the diagnosis of gestational diabetes.
According to the American Diabetes Association, approximately 1 in 10 pregnancies are affected. Typically, women are screened for gestational diabetes using an oral glucose tolerance test (OGTT) early in the third trimester, or earlier in the pregnancy if they are considered to be at higher risk for the condition.
Treatment may include diet and exercise, insulin, and sometimes, oral drugs. We have an entire article on gestational diabetes that explores the risk factors for the condition and the importance of treating it properly, both before and after the pregnancy ends: Gestational Diabetes and the Importance of Postpartum Care.
Women who have already experienced gestational diabetes may have a genetic proclivity to develop insulin resistance, one of the signatures of type 2 diabetes. The latest recommendations from the Women’s Preventive Services Initiative suggest that women with a history of gestational diabetes should be screened for type 2 diabetes within a year of giving birth and “at least every three years for a minimum of 10 years after pregnancy.”
LADA
Latent Autoimmune Diabetes in Adults (LADA) is a form of type 1 diabetes that is particularly slow-progressing. It is usually diagnosed in adults.
At diagnosis, LADA patients generally exhibit hyperglycemia that is less severe than that found in patients with new-onset type 1 diabetes.
Because the onset of the disease is slower than what is typically observed in type 1 diabetes, and usually presents over the age of 35, the condition is often misdiagnosed as type 2 diabetes. LADA patients may not need insulin immediately, and may initially respond well to oral medications such as metformin. It may take years for pancreatic beta-cell failure to progress to the point where the patient needs to manage their blood glucose intensively, as in type 1 diabetes.
LADA can be diagnosed via specific antibody tests. It is estimated that within about five years, all LADA patients will require insulin in some capacity. You can learn more about LADA here.
MODY
Maturity-Onset Diabetes of the Young (MODY) is a specific hereditary form of diabetes in which the pancreas cannot produce enough insulin.
This form of diabetes is rare, and practitioners often misdiagnose people with either type 1 or type 2 initially. The correct diagnosis can be made with genetic testing.
MODY superficially resembles type 2 diabetes: It causes chronic hyperglycemia, but patients do not necessarily require insulin. It can also lead to the same long-term complications as type 1 and 2 diabetes.
MODY is usually caused by a mutation to a single gene, and the severity of the condition varies somewhat depending on the specific inherited gene. Genetic testing can help refine exactly what subtype of MODY a patient has. Treatment may include oral drugs (sulfonylureas), insulin, and/or lifestyle modifications, depending on the situation.
You can learn more about MODY by reading this comprehensive article.
Type 3c Diabetes / Secondary Diabetes
Type 3c diabetes or secondary diabetes refers to blood sugar dysregulation that occurs due to direct trauma to the pancreas, such as that from surgery, chemical treatment, or unrelated endocrine diseases. For example, pancreatic cancer patients may experience damage to the pancreas as a result of the disease and/or treatment, resulting in insulin resistance or deficiency.
It is possible that type 3c diabetes is actually more common than type 1 diabetes, and that misdiagnoses are extremely common.
The use of certain medications, such as steroids and some antipsychotics, have also been associated with the development of secondary diabetes.
It’s difficult to generalize about treatment options, because the scale of glucose intolerance will vary from one patient to another. Treatment may more or less resemble the treatment for type 1 or type 2 diabetes, but clinicians have a better chance of identifying an optimal treatment regimen if they know that they are dealing with type 3c.
In extreme cases — such as after a total pancreatectomy — type 3c diabetes requires more than just insulin. The pancreas has many functions in the body, some of which are quite healthy in most people with diabetes, such as the secretion of digestive enzymes. A total loss of pancreatic function can be a challenging condition to manage.