MODY is a form of monogenic diabetes that may not present any symptoms or could appear like type 1 or type 2 diabetes. This can also lead to misdiagnosis and treatments that don’t work effectively.
It wasn’t until a quarter century after being diagnosed with type 1 diabetes (T1D) that Lori Salsbury in Arkansas realized the condition she’d been living with since she was 15 years old might not be what she thought it was.
Though her mom and sister were both initially misdiagnosed with type 2 diabetes (T2D) and later correctly diagnosed with T1D, Lori didn’t have a reason at first to be suspicious of her own T1D diagnosis.
Not until much later did she realize something was off. The particulars of her T1D just “didn’t match” what she saw others in the community sharing, or what doctors and nurses described as the symptoms most experience when they’re newly diagnosed.
For Salsbury, the diagnosis in her mid-20s brought a number of observations:
- she seemed quite healthy
- no nausea or illness, even a full day after missing an insulin dose when many with T1D may experience high blood sugars leading to those symptoms
- her insulin dosing needs would change frequently, often sending her into super high glucose levels for weeks until adjusting her insulin or carb ratios
- the same would happen on the low end of the scale
One day, Salsbury heard about a rare, inherited form of diabetes called
That piqued her interest, and it led her to a new diabetes diagnosis, better management, and improved overall health.
MODY is that it’s a
This is different than the typical features observed with new T1D and T2D.
Research estimates suggest less than 5% of people with diabetes have a monogenic form of diabetes, and only
The term MODY was first coined in the 1970s by pioneering researchers who identified what appeared to be a mild form of diabetes in children that didn’t necessarily require insulin as was needed for those with the more common “juvenile diabetes” (before it was later renamed type 1).
At that time, MODY was
MODY is
While MODY is most often diagnosed in children and young adults before they reach 25, it may also be diagnosed after that age. Research points to people diagnosed after 35 or 40, when there is clinical suspicion and appropriate genetic testing.
While children have a roughly
Gene mutations aren’t the same for everyone and affect different organs in the body, making them difficult to diagnose without genetic testing. It can also be more challenging to recognize glucose fluctuations commonly found in newly diagnosed patients.
How many types of MODY exist?
Currently, there are
The different genes vary with respect to age of onset, response to treatment, and the presence of extra-pancreatic manifestations.
However, not all carry the same validity, and they may not all be included in diagnostic panels for gene testing.
Three of the most common types of MODY are:
- MODY 1. Gene mutation in the hepatocyte nuclear factor 4 alpha (HNF4A). Although it’s less common, it may account for 5% to 10% of MODY cases.
- MODY 2. Gene mutations in the glucokinase (GCK) enzyme account for 30% to 50% of the cases of MODY. Patients with a GCK mutation typically display “mild and nonprogressive hyperglycemia,” which is generally not symptomatic, meaning they don’t notice it.
- MODY 3. Gene mutation in the hepatocyte nuclear factor 1 alpha (HNF1A) accounts for 30% to 50% of MODY cases. This is a progressive beta cell dysfunction, and diagnosis is typically made between ages 21 and 26.
In recent years, finding out the probability of developing MODY has become more accessible. This is in part due to awareness, and also because of newer public-facing tools like an online probability calculator and subtype app developed by the Exeter Centre of Excellence for Diabetes Research (EXCEED) in the United Kingdom.
Yes, MODY misdiagnosis is relatively common.
Research estimates indicate that as many as 90% of people with MODY may receive a misdiagnosis of either T1D or T2D.
This is because there are no distinct clinical markers for MODY compared to the other types. Many with MODY experience the same common diabetes symptoms:
- extreme thirst
- increased urination
- weight loss.
Some forms of MODY also do not produce any symptoms.
That is why genetic testing is the only true way to diagnose MODY, compared to other types of diabetes — including T1D, which researchers now believe begins at an early pre-clinical stage and eventually leads to symptoms that can become life threatening.
While MODY is still less common and infrequently discussed in clinics, it often comes down to that particular doctor or patient recognizing something might be “different” about their diabetes.
That’s what led Salsburg to eventually receive a MODY diagnosis.
Salsbury did some online research and then consulted her endocrinologist and received antibody tests that came back negative. Her doctor also ordered a C-peptide test that showed levels consistent with T1D, likely a reflection of her diminished insulin production during her time since diagnosis.
came back at T1D levels, but that was most likely due to her 20+ years of using insulin.
A referral to a geneticist led to more bloodwork, and the findings eventually showed a genetic mutation, which causes one of the several different known types of MODY.
MODY has the potential to change how you manage your diabetes, depending on the particular form you’re diagnosed with. Some changes could include stopping medications completely or switching from insulin to a different injectable or oral medication, while some MODY forms mandate changes in your diet.
In Salsbury’s case, the MODY diagnosis brought her some clarity, and finally an explanation of why her diabetes experience seemed so different than others in the T1D community. But she continues insulin therapy.
“Most often, if asked, I just tell people that I was diagnosed with type 1,” Salsbury said. “It’s easier than going through the whole ‘What is MODY?’ spiel.”
Once MODY is recognized and diagnosed, it can also be difficult to regulate glucose levels in the same ways that T1D and T2D often do, because the symptoms and glucose levels can vary significantly.
For Salsbury, the particular BLK gene mutation discovered in her genetic testing led to a
This has led to her needing to work with her healthcare team on adjusting insulin doses frequently and also adopting different glucose goals as her insulin needs change.
But that is not the same for everyone.
In New York, Laurie Jones shared her story of being diagnosed at 30 with gestational diabetes late in her first pregnancy through the test often given to pregnant people.
She changed her eating style and followed it to the letter on exact carb and calorie allowances, and took varying doses of long and short-acting insulins.
Though she describes it as “intense,” all signs of diabetes went away after her first pregnancy.
But within a few years, during her second pregnancy, gestational diabetes returned. She began insulin injections right away as well as a strict diet, but Jones found it more difficult than before to regulate high and low blood sugars.
A number of years later, her A1C results were rising, and that led to a T2D diagnosis. She took Metformin on the advice of her doctor, but it didn’t work to keep her blood sugars in check.
“Most adult medication endos do not push for MODY testing even when the medication is not working,” she explained. “Being overweight is usually assumed to be the reason; therefore, even star doctors don’t push for MODY testing unless weight is lost.”
Her son’s diagnosis changed everything. He developed T1D-like symptoms as a young child, but an endocrinologist eventually ordered genetic testing and led to a MODY 2 diagnosis. After her son’s diagnosis, Jones got her own genetic testing and learned she also had MODY 2.
Most controlled by diet, MODY 2 is one of the more common but less intensive forms of MODY that usually doesn’t require insulin or other glucose-lowering meds.
That led her to stopping Metformin, and she’s been eating healthier and managing her weight for better glucose levels.
“MODY 2 is not just about how you produce or use insulin, but mainly when you produce the insulin,” she said. “We were both told that our pancreas is like a house cooling or heating system that is off-kilter. Basically, our sugar levels have to get much higher than what is considered normal before the pancreas produces insulin. There are also insulin efficiency issues.”
Without her son’s diagnosis, Jones doesn’t think she would’ve ever had the needed genetic testing and would have remained with a T2D diagnosis, taking the wrong medications.
That’s likely the story for so many people in the Diabetes Community, she believes.
“With a 50% chance of being passed on, chances are MODY is not as rare as it is now believed,” Salsbury said. “If more people knew of it and were tested, we may come to find out that it is more common than currently diagnosed.”
MODY is a form of monogenic diabetes that may appear like new onset type 1 or type 2 diabetes, or without any symptoms at all. This can lead to a misdiagnosis, where you aren’t given an accurate T1D or T2D diagnosis to begin treating that as needed.
Genetic testing is the only concrete way to diagnose MODY, which can be passed down genetically in families.
If your diabetes treatment like insulin or pills is not working and you may feel that your symptoms “don’t match” what you understand from the other diabetes types, consult your care team to possibly discuss additional testing or diagnostic measures.