Having had Type 1 diabetes for nearly ten years now, I can handle most diabetic terms and acronyms thrown my way. Hemoglobin A1c? Got it. Carb ratios? Insulin sensitivity? No problem. But one term has continued to confuse me: LADA. Short for Latent Autoimmune Diabetes in Adults, it’s also known as Slow-Onset Type 1 Diabetes, Type 1.5 Diabetes or, occasionally, Late-Onset Autoimmune Diabetes of Adulthood. Four names for the same thing? That’s never a good sign.
Until recently, the most common definition I’d heard for LADA was that it was a Type 1-like form of diabetes diagnosed in adulthood. But I didn’t understand the details. Does being diagnosed with Type 1 diabetes as an adult automatically mean you have LADA? Is there a difference between LADA and the classical definition of Type 1?
To answer these questions, I spoke with Marie Nierras, the program officer of the genetics programs at Juvenile Diabetes Research Foundation. She cut right to the chase. “There is a lot of confusion about LADA,” she told me, “but Type 1 diabetes and LADA are not the same thing.”
Here, to get us started, is how JDRF’s Adults With Type 1 toolkit defines LADA:
“Type 1 diabetes diagnosed in adults over 30 may be Latent Autoimmune Diabetes in Adults (LADA), sometimes known as Type 1.5 Diabetes. LADA is often misdiagnosed as type 2 diabetes because of age; however people with LADA do not have insulin resistance like those with type 2. LADA is characterized by age, a lack of family history of type 2 diabetes, a gradual increase in insulin requirements, positive antibodies, and decreasing ability to make insulin as indicated by a low C-peptide.”
And here’s some further detail from the National Institutes of Health :
“Most people with LADA still produce their own insulin when first diagnosed, like those with type 2 diabetes. In the early stages of the disease, people with LADA do not require insulin injections. Instead, they control their blood glucose levels with meal planning, physical activity, and oral diabetes medications. However, several years after diagnosis, people with LADA must take insulin to control blood glucose levels. As LADA progresses, the beta cells of the pancreas may no longer make insulin because the body’s immune system has attacked and destroyed them, as in type 1 diabetes.”
Many people assume that the first line of the JDRF definition – i.e. an older age at diagnosis – is LADA’s most important characteristic. But it turns out that’s not true. According to Nierras, the key difference between Type 1 diabetes and LADA is not the age of the person when they’re diagnosed, but the gradual way the disease progresses. Whereas people with classical Type 1 diabetes tend to be completely insulin dependent within twelve months after diagnosis (usually less), people with LADA can often survive without artificial insulin for years. As Nierras explains, “It’s as though they have Type 1 diabetes, but something slows down the disease so they can stay off of insulin much longer than the classically definable Type 1.”
With that said, age does play a part: for reasons not entirely understood, the older you are when you’re diagnosed with autoimmune diabetes (i.e. Type 1), the longer it usually takes for your immune system to kill off all your insulin-producing cells. A five-year old with autoimmune diabetes typically becomes insulin-dependent more quickly than a 45-year old – a phenomenon researchers are struggling to understand. But it’s possible, says Nierras, for that same 45-year-old to present with a classic, fast-developing case of Type 1, or for a younger person to present with signs of LADA. According to Nierras, our tendency to emphasize age comes from arbitrary lines drawn by clinical trials — since most trials for Type 1 diabetes only accept people under 30 years old, new cases of Type 1 in people over 30 often are tossed into a generic LADA “junk drawer,” even though age itself is not the defining characteristic of the disease.
All of this might sound like semantics if you already know you have insulin-dependent diabetes. But for people whose diabetes is not quite so clear-cut, LADA is associated with a big, under-acknowledged problem: thanks to the ambiguity of its symptoms, it’s often misdiagnosed as Type 2 diabetes.
Imagine you’re a doctor and a patient comes in, 40 years old, not obese but also not lean, with high blood sugar but no signs of diabetic ketoacidosis (a warning sign for Type 1). What’s more, the patient responds well to meal planning and diabetes pills (both of which, according to Diabetes Monitor, are sometimes effective in early stages of LADA). If you aren’t aware of this weird hybrid – I like to think of LADA as the Prius of diabetes – wouldn’t you think she had Type 2?
Unfortunately, this example is not purely hypothetical – according to the National Institutes of Health, up to 10 percent of people who have been diagnosed with Type 2 diabetes may actually have LADA. This can lead to months, if not years, of incorrect treatment – which puts people at risk of going into diabetic ketoacidosis and developing long-term complications (not to mention spending a long period of time feeling inexplicably rotten).
So what’s the bottom line? If you’ve been diagnosed with Type 2 diabetes and your ability to control your blood sugar with oral medications and lifestyle changes has decreased over time, you might want to be tested for LADA – especially if you are normal weight and don’t have any relatives with Type 2 diabetes. (Tests for LADA are the same as for Type 1 – a blood test to see if any autoantibodies are present, and a measure of C-peptide levels to determine how much insulin you are producing.) The bad news of LADA is that if you have it, you will eventually need to take artificial insulin. But there’s positive news as well: once you’ve been diagnosed correctly and start the right treatment, you can get back on the road to good health.
Postscript: Although there aren’t many clinical trials focused on LADA (here’s one exception), it does pose several fascinating questions, such as whether there’s a genetic connection between Type 1 and LADA and, if so, why one form of the disease progresses more slowly than the other. The challenge, Nierras says, is that people with confirmed cases of LADA are “hard to find and clinically confusing.” Anyone want to lead a drive for more LADA research?
Additional information about LADA:
Catherine Price is a regular contributor to ASweetLife, she writes the blog The Reluctant Diabetic