Has Your Type 2 Diabetes Been Misdiagnosed?

Rosemary Black

Reviewed by QualityHealth's Medical Advisory Board

You've been told that you have type 2 diabetes, you’re taking the prescribed medications, and you’re carefully monitoring your diet. Yet no matter how diligent you are, your blood sugar is still elevated.

If this sounds familiar, you might not have type 2 diabetes. Instead, you may have latent autoimmune diabetes in adults (LADA), a tricky-to-diagnose form of the disease that shares symptoms with both type 1 and type 2 diabetes.

What Is LADA?

Diabetes patients have elevated blood glucose (sugar) levels, meaning that sugar, the body’s main source of energy, cannot get from the blood into their cells. It’s insulin, a hormone produced by the pancreas, that allows sugar to enter the cells. In patients with type 1 diabetes, the pancreas don’t produce enough insulin; in type 2 diabetes, insulin isn’t used efficiently.

It’s not easy to classify or identify LADA, which, like type 2 diabetes, "develops slowly in adults and occurs in people who are older than 30 years, with the majority diagnosed at 60 to 65 years old," explains Joel Zonszein, MD, director of the Clinical Diabetes Center at Montefiore Medical Center in New York City. (Patients with type 1 diabetes are usually younger when diagnosed). But like type 1, LADA is actually an autoimmune disease in which an individual's immune system begins to attack insulin-producing beta cells in the pancreas. Because LADA has features associated with both type 1 and type 2 diabetes, it is often called type 1.5 diabetes.

Delayed Diagnoses

While "Type 1 diabetes is usually diagnosed within one to six weeks from the onset of symptoms," according to Amber Taylor, MD, director of the Diabetes Center at Mercy Medical Center in Baltimore, "LADA can take six months to a couple of years to diagnose."

"LADA is often misdiagnosed and treated as type 2 diabetes," Zonszein says. This is due in part to the overlap in features between these forms of the disease. In addition, after LADA patients are diagnosed with type 2 diabetes, "The blood sugars initially improve with lifestyle changes and oral medications, so many physicians believe that the person has type 2 diabetes. The proper diagnosis of LADA remains a challenge for the physician," he adds.

All this adds up to LADA being "much more prevalent than you might think," says Spyros Mezitis, MD, MPH, of Lenox Hill Hospital in New York City. In fact, "as many as 10 percent of people diagnosed with type 2 diabetes have LADA," according to the National Diabetes Information Clearinghouse. This means it is probably more common than type 1 diabetes.

Do You Fit the Profile for LADA?

Here are some signs that you may have LADA rather than type 2 diabetes:

You're thin. The vast majority of individuals with type 2 diabetes are overweight or obese, explains Zonszein. "If the person is not obese, this can indicate LADA," he says.
You don't have a family history of type 2 diabetes. If you don’t have a parent or sibling with type 2, you’re less likely to have type 2 diabetes yourself.
You have another autoimmune disease, such as lupus or rheumatoid arthritis. If you have one autoimmune disease, you're more likely to get another one.

None of these signs on their own is enough to diagnose LADA, but "When someone develops diabetes as an adult, it's easy to assume that it is type 2," Zonszein says. "But if the person has no family history of type 2 diabetes, the person is not obese, and the person has another autoimmune disease, we immediately suspect LADA."

How Is LADA Diagnosed?

To confirm a diagnosis of LADA, your health care provider will do a thorough physical examination and take a detailed family history. He or she will also run blood tests to check for signs of damage to the insulin-producing beta cells of the pancreas in the form of islet cell antibody and C-peptide levels. Islet cell antibodies are proteins produced by the immune system; they damage beta cells. C-peptides are released by the pancreas along with insulin; C-peptide levels show how much insulin you’re producing, Zonszein explains. "These tests tell us how much beta cell function a person has," he says. "If the islet cell antibodies are high and the C-peptide level is low, this indicates LADA."

Treating LADA

Since it comes on so gradually, a person with LADA may take oral medications for a while. But oral medications stop working at a certain point, Mezitis says.

Ultimately LADA patients are prescribed insulin. "Our job is to mimic what the pancreas could do, if it could make insulin," Taylor says. "Once the disease process has run its course, the treatment for LADA is insulin."

If you do have LADA, the sooner you find out, the sooner you can start a treatment that will help you feel better, bring your blood sugar into the normal range, and help prevent the health-threatening complications that can occur with uncontrolled diabetes.

Amber Taylor, MD, reviewed this article.