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Most people are familiar with the two main types of diabetes — type 1 and type 2. But for some, the path to diagnosis isn’t so straightforward. You might be diagnosed with one type, only to find later that your body shows signs of both. This mixed presentation can make it harder to understand your condition and figure out the right treatment.
This article looks at a condition called double diabetes, also known as type 1.5 diabetes or latent autoimmune diabetes in adults (LADA). We’ll explain what it is, how it develops, and why it’s sometimes confused with other forms of diabetes. We’ll also discuss signs that your diagnosis might not tell the full story — and when to talk with your doctor about more testing.
Double diabetes happens when a person shows signs of both type 1 and type 2 diabetes. In type 1, the immune system attacks cells in the pancreas that make insulin, a hormone that helps move glucose (sugar) from the blood into cells for energy. In type 2, the body still makes insulin but can’t use it properly, causing insulin resistance.
With double diabetes, both problems occur together — the body has trouble making and using insulin. This can make blood sugar levels harder to control and raise the risk of complications, such as cardiovascular (heart and blood vessel) disease or kidney disease.
Researchers believe that double diabetes may develop in different ways. Some people with type 1 may become insulin resistant over time, similar to someone with type 2. This can be linked to factors such as a higher body weight, a lack of physical activity, or certain genetic traits. Other people may first have type 2 but later develop an autoimmune response that attacks their beta cells (insulin-making cells in the pancreas).
A condition called metabolic syndrome often plays a role. This means a person has several health problems at the same time, such as:
These changes make the body more resistant to insulin and raise the risk of heart disease and type 2 diabetes. When someone with type 1 diabetes has metabolic syndrome, their chances of developing double diabetes go up. About 1 in 4 people living with type 1 also have metabolic syndrome.
Anyone with type 1 or 2 diabetes can develop double diabetes, but people with type 1 diabetes who gain a significant amount of weight are at greater risk than others. This is because excess body fat, especially around the waist, increases insulin resistance. Having a family history of type 2, high cholesterol levels, or high blood pressure also raises risk.
According to the American Diabetes Association, people with overweight or obesity can lower their risk of insulin resistance by losing 7 percent to 10 percent of their body weight. The American Diabetes Association also recommends staying active and quitting smoking to lower your risk.
Certain clues may indicate double diabetes. One of the first signs may be high blood sugar levels that are hard to control, even with typical type 2 diabetes treatment. Other possible signs and symptoms include:
In some cases, a person may develop diabetic ketoacidosis (DKA). This serious condition occurs when the body can’t use sugar for energy and starts breaking down fat instead. In DKA, the body releases acids called ketones into the blood, which can be life-threatening if not treated quickly. DKA is more common in type 1 diabetes. So, when it happens to someone with type 2 diabetes, doctors may suspect double diabetes.
Doctors rely on several blood tests to determine whether someone has type 1 or type 2 diabetes — or features of both. The glutamic acid decarboxylase (GAD) antibody test looks for GAD antibodies (immune proteins), which show that the immune system is attacking the pancreas. A positive test result indicates an autoimmune condition like type 1 diabetes.
A C-peptide test, which measures how much insulin the body still makes, may also be helpful. Very low C-peptide levels mean the pancreas has stopped producing enough insulin, pointing to type 1 diabetes. Normal or high levels suggest type 2, in which the body makes insulin but doesn’t use it properly.
Testing positive for GAD antibodies, along with signs of insulin resistance or high C-peptide levels, may lead to a diagnosis of double diabetes.
Getting the right diabetes diagnosis doesn’t always happen right away. Many adults who develop type 1 are first told they have type 2. Research from the American Diabetes Association and European Association for the Study of Diabetes shows that more than 40 percent of people diagnosed with type 1 after age 30 are initially treated for type 2. As a result, some people may spend years managing their diabetes with the wrong treatment.
Misdiagnosis can happen because the two types share many features. Older adults with type 1 might not be thin, and young people with type 2 may not have a higher body weight. Some people have traits of both conditions, which can make diagnosis even harder. GAD antibody levels can also drop over time, especially if type 1 diabetes has gone undiagnosed.
Certain signs may suggest that your diabetes type isn’t what you were originally told. You might be losing weight even though you’re eating as usual, or your blood sugar levels may stay high even if you have made lifestyle changes or take medication.
Frequent infections, intense thirst, or an episode of DKA could also be clues. If these changes occur, talk with your healthcare provider about further evaluation or blood testing.
Managing double diabetes means treating both insulin resistance and low insulin production. Most people need insulin therapy — through injections or an insulin pump — along with medicines like metformin to improve how well the body uses insulin. Regular blood sugar checks can help prevent both highs and lows.
Eating a nutritious diet, getting regular physical activity, and maintaining a healthy weight also play a big role in managing blood sugar. Because diabetes raises the risk of heart and kidney disease, your doctor will also keep an eye on your blood pressure and cholesterol levels, as well as other long-term complications.
On DiabetesTeam, people share their experiences with type 2 diabetes, get advice, and find support from others who understand.
Have you been diagnosed with double diabetes? Let others know in the comments below.
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