LADA Diabetes (Type 1.5): Signs, Tests, Treatment

LADA — latent autoimmune diabetes in adults — is an autoimmune form of diabetes that develops slowly in adulthood. Because it starts after 30 and often responds to tablets at first, it is frequently mistaken for type 2 diabetes. Getting the diagnosis right matters: LADA needs insulin sooner, and some type 2 medicines are a poor fit.

LADA at a glance

	Type 1	LADA	Type 2
Cause	Autoimmune destruction of insulin-producing beta cells	Same autoimmune process, but much slower	Insulin resistance plus gradual loss of insulin secretion
Typical age at diagnosis	Childhood to young adulthood (can occur at any age)	30 and older	Usually over 40, increasingly younger
Islet autoantibodies (e.g. GAD)	Present	Present	Absent
Insulin needed	From diagnosis	Not at first, usually within months to years	Often not for many years, sometimes never
Body weight	Often normal	Often normal, but can be overweight	Usually overweight

LADA is sometimes called "type 1.5 diabetes". Medically, most experts regard it as a slowly progressing form of type 1 diabetes in adults.

How common is LADA?

LADA is not rare. Studies estimate that about 2 to 12 percent of adults with diabetes have it, and roughly 4 to 14 percent of adults first labeled as having type 2 diabetes turn out to carry the antibodies typical of LADA. Many cases are never identified because nobody tests for them.

What causes LADA?

As in type 1 diabetes, the immune system mistakenly attacks the beta cells in the pancreas that make insulin. In LADA this happens slowly, so for a while the remaining cells still produce enough insulin to keep blood sugar near normal with diet, exercise or tablets. As more beta cells are lost, blood sugar rises and insulin becomes necessary. Genetics play a role, and LADA is more common in people who have — or whose families have — other autoimmune conditions such as autoimmune thyroid disease or celiac disease. Some people with LADA also have a degree of insulin resistance, which blurs the line to type 2.

Symptoms

The symptoms are those of high blood sugar and often develop over weeks to months:

Increased thirst and frequent urination, including at night
Tiredness and lack of energy
Unintended weight loss
Blurred vision
Slow-healing cuts and frequent infections (skin, gums, urinary tract)
Tingling in the hands or feet (later)

As insulin production falls further, people with LADA can develop diabetic ketoacidosis (DKA) — a dangerous build-up of ketones. Nausea, vomiting, abdominal pain, deep rapid breathing or fruity-smelling breath with high blood sugar need emergency care.

Signs that "type 2" might actually be LADA

Ask your doctor about antibody testing if several of these apply:

You were diagnosed between about 30 and 50 years of age.
You are not overweight, or you lost weight before the diagnosis.
You or close relatives have another autoimmune disease (thyroid disease, celiac disease, vitiligo, type 1 diabetes).
Blood sugar stays high or keeps rising despite tablets, diet and exercise — often within a few years of diagnosis.
You do not have typical features of metabolic syndrome such as high blood pressure and high triglycerides.

Diagnosis: antibodies and C-peptide

Diabetes itself is diagnosed with the usual tests: fasting glucose of 126 mg/dL or more, HbA1c of 6.5% or more, or a 2-hour glucose tolerance result of 200 mg/dL or more. To tell LADA apart from type 2, two further blood tests are used:

Islet autoantibodies — most importantly antibodies against GAD65 (GADA). Others are IA-2, ZnT8 and islet cell antibodies. A positive result confirms the autoimmune nature; high GAD levels predict a faster need for insulin.
C-peptide — a by-product of the body's own insulin production. Low or falling C-peptide shows that the beta cells are failing and guides treatment.

Commonly used criteria for LADA are: age 30 or older at diagnosis, at least one positive islet autoantibody, and no need for insulin during the first six months after diagnosis.

Treatment

The goals are the same as in every type of diabetes — blood sugar in target, HbA1c usually below 7%, and protection of the heart, kidneys, eyes and nerves. What differs is how quickly insulin is needed. An international expert panel recommends basing treatment on C-peptide:

C-peptide	Typical approach
Very low (below about 0.3 nmol/L)	Treat like type 1 diabetes: insulin with mealtime and basal doses.
Intermediate (about 0.3–0.7 nmol/L)	Insulin is often started, sometimes combined with other medicines; C-peptide is re-checked regularly.
Preserved (above about 0.7 nmol/L)	Medicines used in type 2 diabetes can work for a while, with regular monitoring of C-peptide and glucose.

Points that often come up:

Sulfonylureas (such as glipizide or glimepiride) are generally avoided in LADA, because they push failing beta cells harder and may speed up their loss.
Metformin, DPP-4 inhibitors and GLP-1 receptor agonists can be used while enough insulin is still produced.
SGLT2 inhibitors need caution: in autoimmune diabetes they raise the risk of ketoacidosis, sometimes with near-normal blood sugar.
Starting insulin early is not a failure. It is often the safest way to keep glucose in range when beta cells are declining.

Your doctor will choose the treatment with you; never change or stop medication on your own.

Living with LADA

Monitor your glucose regularly — and more closely when starting insulin. A continuous glucose monitor (CGM) can help. See how to measure blood sugar.
Eat well: plenty of vegetables, legumes, whole grains, fish and nuts, and fewer sugary drinks and highly processed foods. Learning to match insulin to carbohydrates becomes important once you use mealtime insulin. Ideas: 10 foods for blood sugar control.
Stay active — at least 150 minutes a week — and learn how exercise affects your glucose.
Know how to treat a low once you use insulin: the 15-15 rule.
Get yearly checks of eyes, kidneys, feet, blood pressure and cholesterol, and screening for thyroid disease and celiac disease, which are more common with autoimmune diabetes.
Don't smoke, and keep alcohol moderate.

Outlook

With the right diagnosis and treatment, people with LADA can keep their blood sugar well controlled and lead full lives. Over time, the risk of diabetes complications in LADA is similar to other types of diabetes and depends mainly on long-term glucose, blood pressure and cholesterol control — which is why recognising LADA early, and not leaving blood sugar too high for too long on unsuitable treatment, makes a real difference.

General information, not medical advice. Follow the treatment plan agreed with your doctor or diabetes team. In an emergency, call 911 (US) or your local emergency number.