What Are the Subtypes of Type 2 Diabetes?

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Type 2 diabetes is diagnosed based on high blood glucose (sugar) levels, or hyperglycemia. However, the degree to which the body is affected and the factors that led to type 2 diabetes determine how healthcare providers classify the disease.

The subtypes of type 2 diabetes differ in their characteristics and also have different risks of diabetes-related complications and outcomes. This article discusses the four main subtypes of diabetes related to type 2 diabetes, including their causes and risks for complications.

A healthcare provider shows a person with type 2 diabetes how to test blood sugar

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Severe Insulin-Deficient Diabetes (SIDD)

Severe insulin-deficient diabetes is a subtype resembling another subtype called severe autoimmune diabetes (SAID). People with SIDD tend to be young, have a lower-than-average body mass index (BMI), and have higher hemoglobin A1c levels (an indicator of average blood glucose over the past several weeks) at diagnosis.

Due to damaged beta cells (the cells that produce insulin) in the pancreas, with SIDD, insulin production also is low. Insulin is a hormone that allows cells to take in glucose to use for energy. Treatment for people with SIDD may include insulin as well as oral medications.

Retinopathy in SIDD

The SIDD subtype seems to have a high risk of retinopathy (disease of the retina, the light-sensitive retina of the eye), and subsequently, vision loss.

Diabetic eye disease develops when high blood glucose levels cause damage to tiny blood vessels in the eye. It can eventually lead to vision loss and blindness. If you have diabetes, it’s very important to get regular eye exams to help with early detection and treatment.  

Severe Autoimmune Diabetes (SAID) in Type 1 Diabetes

Severe autoimmune diabetes is a subtype of type 1 diabetes. In people with this subtype, the immune system produces antibodies that destroy the beta cells within the pancreas. This is known as an autoimmune response.

The difference between SAID and SIDD is that antibodies are not present in people with SAID, which means the immune system isn't the root cause of their diabetes. People with SAID and type 1 diabetes require insulin replacement therapy via injection or insulin pump due to their bodies not producing insulin on their own.

People with SIDD subtype diabetes have insufficient beta cell function, but the reason is unknown.

Severe Insulin-Resistant Diabetes (SIRD)

Severe insulin-resistant diabetes is a subtype characterized by high insulin resistance.  This means the body is still making insulin but doesn't properly respond to it. People with SIRD tend to be overweight, which can further contribute to insulin resistance.

People with SIRD have a higher risk of developing nephropathy (kidney disease) and nonalcoholic fatty liver disease (NAFLD).

Identifying people with this subtype of diabetes may help healthcare providers further identify those at the highest risk for kidney and liver disease. With this information, a provider can develop treatment plans to help prevent or delay kidney disease and NAFLD onset and progression.

SIRD and the Risk for Kidney Disease and Fatty Liver

The SIRD subtype of diabetes is strongly associated with a high risk of nephropathy (kidney disease) and nonalcoholic fatty liver disease (NAFLD).

Kidney disease can develop in people with diabetes when blood vessels within the kidneys are damaged due to high blood glucose levels. In turn, this may also lead to high blood pressure, which can cause additional damage to the kidneys.

NAFLD is strongly associated with overweight/obesity and insulin resistance. Other risk factors for NAFLD include having metabolic syndrome (a group of conditions that can lead to type 2 diabetes, heart disease, and stroke), high triglycerides (a type of fat in the blood), and low levels of high-density lipoprotein (HDL) cholesterol, considered the "good" cholesterol.

Mild Obesity-Related Diabetes (MOD)

Mild obesity-related diabetes (MOD) is characterized by a high body mass index, but not insulin resistance. This subtype is considered a milder form of diabetes. It does not come with as many metabolic issues as the other subtypes.

Due to low levels of insulin resistance and high BMI seen in people with MOD, it is believed to be brought on by problems caused by overweight and obesity.


Body mass index is a dated, biased measure that doesn’t account for several factors, such as body composition, ethnicity, race, gender, and age. Despite being a flawed measure, BMI is widely used today in the medical community because it is an inexpensive and quick method for analyzing potential health status and outcomes.

Mild Age-Related Diabetes (MARD)

Mild age-related diabetes (MARD) is characterized by older age and late-onset of diabetes. This subtype appears to be the most common. People with MARD have mild difficulty with managing their blood glucose levels and have a low risk of complications. This is the most common subtype of diabetes.


Research has identified different clusters, or subtypes, of type 2 diabetes. These subtypes are determined based on the degree to which the body is affected and the causes or factors that led to the development of diabetes in individuals.

The subtypes include severe insulin-deficient diabetes (SIDD), severe insulin-resistant diabetes (SIRD), mild obesity-related diabetes (MOD), and mild age-related diabetes (MARD).

A Word From Verywell 

With diabetes being a complex condition, classifying people into different subtypes of diabetes may help develop individualized treatment plans—targeting people who will benefit the most from certain therapies and prevention measures. Knowing your subtype of diabetes can lay the foundation for more personalized diabetes care.

Frequently Asked Questions

  • What’s the difference between type 1 and type 2 diabetes?

    Both type 1 and type 2 diabetes are chronic (long-term) medical conditions. While type 1 diabetes is an autoimmune condition, type 2 diabetes is often a result of insulin resistance (the body is not able to properly use insulin).

    People with type 2 diabetes can usually still make some insulin in their body, whereas people with type 1 diabetes cannot and require exogenous (from outside the body) insulin in order to survive.

  • Which type of diabetes is most serious?

    All types of diabetes are serious medical conditions. However, when looking at the subtypes of diabetes, patients who have SIRD are at the highest risk of developing nephropathy (kidney disease) and nonalcoholic fatty liver disease (NAFLD). People with SIDD are at the highest risk of developing retinopathy, a type of eye disease.

    Early detection and proper treatment are important in preventing or delaying disease progression and complications. 

  • Are there different degrees of type 2 diabetes?

    Research has identified different clusters, or subtypes, of type 2 diabetes based on the causes or factors that led to an individual's diabetes, as well as the disease progression and development of complications.

    This includes severe insulin-deficient diabetes (SIDD), severe insulin-resistant diabetes (SIRD), mild obesity-related diabetes (MOD), and mild age-related diabetes (MARD).

8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Sarría-Santamera A, Orazumbekova B, Maulenkul T, Gaipov A, Atageldiyeva K. The identification of diabetes mellitus subtypes applying cluster analysis techniques: a systematic review. Int J Environ Res Public Health. 2020;17(24):9523. doi:10.3390/ijerph17249523

  3. National Eye Institute. Diabetic retinopathy.

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  6. American Liver Foundation. NASH causes and risk factors.

  7. National Guideline Centre (UK). Non-Alcoholic Fatty Liver Disease: Assessment and Management. London: National Institute for Health and Care Excellence (NICE); July 2016.

  8. Centers for Disease Control and Prevention. What is diabetes?

By Brittany Poulson, MDA, RDN, CD, CDCES
Brittany Poulson, MDA, RDN, CDCES, is a registered dietitian and certified diabetes care and education specialist.