GAD antibody testing and diabetes

Not sure what a GAD (Glutamic Acid Decarboxylase) antibody test is? Read on to find out why it’s so important.

GAD antibody testing

Lizè van der Walt shares the story of her and her daughter’s diabetes diagnoses, and how they learned the importance of GAD antibody testing.

A GAD antibody test is a blood test that shows the presence of Glutamic Acid Decarboxylase antibodies, which are often used to diagnose Type 1 diabetes. About 75% of people with Type 1 diabetes have GAD antibodies.

Could you tell us your diagnosis story – and your daughter’s diagnosis story?

I was diagnosed at the age of 13, a month before my 14th birthday. As an active teenager participating in a variety of sports and part of a household with healthy eating habits, my mom didn’t think much when I presented with symptoms such as weight loss and exhaustion, thinking it was end-of-the-year stress and hormonal changes. However, after a trip to the mall looking for a swimsuit, she was shocked by the amount of weight I had lost. As a registered nurse, some of the symptoms raised a certain awareness but as a mother, she was deeply concerned about my wellness. The predominant signs that got her anxious were the weight loss, unquenchable thirst, and low energy levels. She made a doctor’s appointment. With a quick finger prick and the blood glucose result of 36mmol/L (normal range 4-8mmol/L), it was confirmed and I was hospitalized immediately.

My youngest daughter was 4 years old when, over a weekend, we went from “normal family” to the ER on a Sunday night with a juvenile diabetic. Her diagnosis was quite a coincidence. I thought she had a bladder infection and did a urine test after I noticed she was urinating a lot and didn’t feel well. The urine test didn’t show any infection but instead ketones and glucose. I phoned our neighbour at the time, a GP, and she recommended we go to the emergency room to get her checked out.

We did 2 blood glucose tests and despite 25 years of experience and knowledge I still couldn’t wrap my head around the numbers that were shown to me.

It was only after the ER doctor gave her the first shot of insulin and placed the bright orange “DIABETIC” sticker on her hospital file I realized what we were facing.

Auto-immune condition

It is important to note that what preceded her diagnosis was that 2 months prior she had Respiratory Syncytial Virus (RSV). Type 1 Diabetes is an auto-immune condition and therefore can manifest in the body after it is under attack from a virus. Symptoms of Type 1 diabetes include the need to urinate often, thirst, constant hunger, weight loss, vision changes, and fatigue. These symptoms may occur suddenly, as we’ve seen with Liya-Lomé.

There have been longitudinal studies done to look at the relationship between enteroviruses and auto-immune disorders such as Type 1 diabetes for years (enteroviruses are a group of viruses and can affect many parts of the body, caused by any of several different viral strains).

It has been found that children who were exposed to enteroviruses are more likely to develop Type 1 diabetes. However, this seems to disproportionately apply to children who carry a genetic variant in a surface protein of pancreatic beta cells. Which means those that have a genetic predisposition to diabetes.

In general, the more enterovirus infections that occur in children, the greater their risk for Type 1 diabetes.

Enterovirus infections and diabetes

It was found that children with diabetes have had about three times more enterovirus infections than those without Type 1 diabetes. While there is no direct causal links identified, it’s believed that enteroviruses can cause damage to the pancreas, thus increasing a child’s risk of suffering from poor or inadequately performing insulin.

Unfortunately, a new study suggests that there may be a link between childhood COVID-19 cases and the development of Type 1 diabetes too. New diagnoses for Type 1 diabetes have almost doubled during the pandemic and many of the children affected have evidence of a COVID-19 infection. It is believed that the coronavirus spike proteins may attack insulin-producing cells in the pancreas and destroy them in the process, thus increasing the risk for Type 1 diabetes in children. A direct link has yet to be proven, but it should still be considered a plausible explanation for the increase in Type 1 diabetes diagnoses during the pandemic.

GAD antibody testing and diabetes

Type 1 diabetes is caused by an abnormality of the beta cells of the islet of Langerhans, which
reduces the production of the hormone insulin (an enzyme that stimulates cells to absorb and use glucose in the blood, and stimulates the liver to convert glucose into glycogen) to reduce blood sugar. Type 1 diabetes usually present quite early in children, however, several cases with similar abnormalities appear in adults called latent auto-immune diabetes of adults (LADA).

GAD (glutamic acid dicarbon hydroxylase) is one of the substances involved in beta cell-specific auto-immune activation. In other words, the interstitial insulin production by pancreatic beta cells requires the enzyme GAD. Therefore, if for some reason the body produces specific anti-GAD antibodies against GAD, then the body will not be able to produce insulin, leading to a build-up of sugar in the blood.

GAD antibody testing determines which type of diabetes you have by measuring the concentration of antibodies against the GAD enzyme in the body.

What is the GAD test for?

The GAD test is often used in the following cases:
1. Assist in the diagnosis of Type 1 diabetes.
2. Determine whether gestational diabetes in pregnant women is Type 1 diabetes or not,
3. Assess risk and monitor the progression of Type 1 diabetes.

75% of patients with Type 1 diabetes have anti-GAD antibodies in their blood, so the GAD antibody test is very important in classifying diabetes, thereby helping to choose the right treatment regimen for the patient. Anti-GAD antibodies may be present together with anti-insulin antibodies or may be the only antibodies in the patient’s blood. In addition, the Anti-GAD antibody test is also relevant to the prognosis of patients with future insulin-dependent transitions, which means it can predict whether or not someone will develop Type 1 diabetes. Although not when.

To have the most accurate results, patients should choose reputable medical facilities to perform screening tests for early diagnosis of diabetes.

This test allows for the detection of the presence of GAD antibodies, which provides early evidence of autoimmune disease activity. Its measurement is useful in assisting the physician in the prediction, diagnosis, and management of patients with diabetes.

What made you decide to get your other daughter tested for GAD antibodies?

We decided to get our other daughter tested for GAD antibodies after our Paediatric Endocrinologist suggested we do the test. I objected, mainly because I felt it was unnecessary… not because I thought it impossible to have both children living with diabetes but because I couldn’t get myself to accept that fate if the dice rolled that way.

My daughter said she wanted the test done so we did. It was a big surprise when it came back positive. After crying and protesting a bit I started my “investigation” and consulted with the doctor to get more information.

To be completely honest, it was only after I came across an awareness campaign of a young lady that passed away after being misdiagnosed, and when the doctor gave me more information that I truly saw the value in knowing your status.

Will you change anything now that you know your second daughter is at risk of developing Type 1?

Yes and no. As a family, we have established healthy eating habits, and she stays active, so there aren’t many lifestyle changes I would make. However, we will definitely do more regular blood tests and overall health check-ups. What my experience has taught me is that the mental health aspect is just as crucial as physical health when facing the possibility of a diagnosis. The shock and emotional toll after being diagnosed or having a child diagnosed with a chronic condition can be mentally exhausting.

Mental preparation is key. It’s important to manage a range of emotions and cultivate a mindset that helps you stay grounded in the present, rather than being consumed by ‘what-ifs.’

While we can’t control the outcome of a diagnosis, we can control how we respond emotionally. This includes finding ways to cope with stress and being mentally prepared to take steps forward, regardless of the diagnosis. Focusing on mental health ensures that we are not only prepared physically, but also emotionally equipped to support our children and ourselves through the process.

What is life like with two people with Type 1 diabetes in the house?

Life with two people who have Type 1 diabetes in the same household is a balance between routine and unpredictability. Some days everything runs smoothly, but other times, unexpected challenges — like dislodged sensors, dead batteries, or running out of insulin — can create moments of chaos. Over time, this has taught me to stay calm and appreciate the peaceful, uneventful days.

As a family, we work together to manage the daily demands. My husband is very capable of taking over when I have tough days, handling tasks like changing sensors and infusion sets. I take charge of organizing lunch boxes, restocking low-sugar supplies, managing prescriptions, and scheduling doctor’s appointments. It’s a team effort, and we keep each other informed if any issues arise.

Open communication and support are essential to keeping everyone safe and healthy.

Our household runs on the principle of ‘Peace, if possible, honesty at all times.’ This is especially important with young children, as feeling judged about what they eat can lead them to hide things or try to manage their diabetes on their own, which can be dangerous.

What do you wish you’d known when you were diagnosed?

Type 1 diabetes is not a life sentence or a terminal illness…I love the quote, “I can do anything… except make insulin”.

I am in charge and make decisions regarding my care, with the input of a great medical team, not the other way around. It is okay to have tough days. Building a strong support system is just as important as learning to manage the condition itself.

What advice would you offer to others who are struggling with diabetes?

My advice? Take it one day at a time, and don’t sweat the small stuff — there’s enough to manage without adding extra pressure!

Celebrate those little victories, whether it’s nailing your time in range blood sugar target or just making it through the day without losing your meter. Find someone who gets it, like a ‘diabetes running buddy,’ who you can share those cringe-worthy diabetes memes with or just vent to when things get tough.

I’ve been through it all — rebellious teenage years, student life, pregnancy, parenting, and now raising a child with a Type 1 diagnosis. It’s a rollercoaster, but I’ve learned that you don’t have to tackle it alone. Laugh when you can, cry when you need to, and remember: you’ve got this — even on the days when your pump doesn’t!

What makes your life sweet?

It’s all about the little things: the love and support of family and close friends, the peace found in nature, the comfort of faith in God, the beauty of art, and the joy of a good cup of coffee.

Dreams keep me looking forward, and all these things combined remind me that life is full of
sweetness—even when there are challenges. Diabetes is just a part of my story, but these joys make the journey richer.

Share your diabetes story

Would you like to share your story, either here or on Facebook (South Africans with Diabetes)? Please email us if you would!