Misdiagnosis of Diabetes

The most likely diagnostic problem with diabetes is failure to diagnose it early because patients do not recognize its early mild symptoms. Once a doctor is seen, diabetes is not often completely misdiagnosed because it is well-known to physicians and has fairly definitive diagnostic tests (blood glucose test; urine glucose test). However, more difficulty is found in determining the correct type of diabetes, diagnosing any complications of diabetes, or associated diseases.

Undiagnosed Diabetes. The most likely misdiagnosis related to diabetes is that it remains undiagnosed in many people. This mostly refers to Type 2 Diabetes, where the disease can take years to progress to major symptoms, but undiagnosed Type 1 Diabetes can occur (though usually becomes visible within weeks or months). Read more about: Symptoms of Diabetes.

Undiagnosed Pre-Diabetes: The milder precursor to Type 2 Diabetes called “pre-diabetes” is often so mild that it can remain undiagnosed for years. Read more about: Pre-Diabetes.

Undiagnosed Gestational Diabetes: Gestational Diabetes can also remain undiagnosed in a pregnant woman. Read more about: Gestational Diabetes.

Acute Complications of Undiagnosed Diabetes: If diabetes is undiagnosed, some of the symptoms and complications can become very dangerous. These can often remain undiagnosed until too late, or can be misdiagnosed as something else. Fatality is possible. The complications include:

Most Dangerous Misdiagnosis: One of the most dangerous errors in diagnosis is to incorrectly diagnose a person with Type 2 Diabetes, sending them home with instructions about diet and how to monitor their blood sugar levels. If they actually have Type 1 Diabetes, insulin is required, and trying to treat it with diet changes alone is likely to result in DKA and even death.

There are real-world examples of this diagnostic mistake. A six-year-old girl died after being sent home in this way, with a Type 2 Diabetes diagnosis, and a diet treatment plan (insulin was required; DKA was the result).

But Type 2 Diabetes is extremely rare in children under 10; it’s almost certainly Type 1 Diabetes in that age group. And an older child or a teenager is actually the most likely age to get Type 1 Diabetes requiring insulin (although the reverse misdiagnosis is possible since some teens are being diagnosed correctly with Type 2 Diabetes).

Another example case is a 29-year-old man sent home with instructions about dieting and monitoring, with a diagnosis of Type 2 Diabetes. Although it’s more likely for a 29-year-old than a 6-year-old to have Type 2 Diabetes, the age is still an unusual age for Type 2 Diabetes. And at 29, the possibility of Type 1 Diabetes is still there, and this was the actual correct diagnosis (insulin was required).

MODY Diabetes is another possibility for a younger adult in their 20’s or 30’s with Type 2 Diabetes, rather than the classic ages of onset for Type 2 Diabetes (40’s or 50’s or later).

Misdiagnosed: The list of conditions that mimic diabetes is not really that long. A total misdiagnosis is highly unlikely.

There are other disorders that cause glycosuria (usually without hyperglycemia). See other uncommon causes of glycosuria.

Hidden Causes (Secondary Diabetes): There are a number of medical conditions that can cause hyperglycemia, diabetes symptoms, or diabetes-like conditions, mainly due to their impact on the pancreas. These conditions may cause disorders that mimic either “insulin deficiency” or “insulin resistance”.

Drug-Related Diabetes: There are a number of drug medications that can sometimes cause diabetes or diabetes-like conditions.

Genetic Syndromes with Increased Diabetic Risk: There are a number of genetic diseases or disorders where the person is at higher risk of diabetes.

Wrong Type of Diabetes: Sometimes people are correctly diagnosed with diabetes, but the wrong subtype is diagnosed. There are two main types of diabetes and a few rare types.

Subtypes of Type 2 Diabetes: There are actually subtypes of the main Type 2 Diabetes, which can affect how to treat it. The main issue is whether your body is producing too much insulin but resisting it (called “insulin-resistant”), or the less common case where your body is producing too little insulin (called “insulin-deficient” type). Detection of insulin resistance (and hyperinsulinemia) makes it very likely that the diabetes is classic Type 2 Diabetes, but the detection of an insulin-deficient type may increase the suspicion of another rarer type of diabetes or secondary diabetes.

Undiagnosed Chronic Complications of Diabetes. The onset of Type 2 Diabetes can be so slow that the complications of diabetes can have time to develop prior to the diabetes being discovered. And once diagnosed, the careful watching for any signs of diabetes complications becomes an ongoing management concern. Read more about diabetes complications, but some of the complications more likely to be undiagnosed include:

Associated (Comorbid) Conditions: Not only is there diabetes, and the various complications of diabetes, but people with diabetes can often have additional diseases. People with Type 1 Diabetes are more likely to have other types of Autoimmune Diseases (e.g. Addison’s Disease). A list of comorbid disorders for Type 1 diabetes includes:

People with Type 2 Diabetes often have three other disorders: hypertension, obesity, and high cholesterol, which is a cluster of four diseases (including diabetes) which is called Metabolic Syndrome (Syndrome X). There are various other associated diseases for diabetes. A list of these comorbid disorders for Type 2 diabetes includes:

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Back to: « Diabetes

Misdiagnosis of Diabetes

Can the A1C test result in a different diagnosis than the blood glucose tests?

Yes. In some people, a blood glucose test may indicate a diagnosis of diabetes while an A1C test does not. The reverse can also occur—an A1C test may indicate a diagnosis of diabetes even though a blood glucose test does not. Because of these variations in test results, health care providers repeat tests before making a diagnosis.

People with differing test results may be in an early stage of the disease, where blood glucose levels have not risen high enough to show on every test. Sometimes, making simple changes in lifestyle—losing a small amount of weight and increasing physical activity—can help people in this early stage reverse diabetes or delay its onset.

More information about diagnosing diabetes and prediabetes is provided in the NIDDK health topic, Diagnosis of Diabetes and Prediabetes, or by calling 1-800-860-8747.

Source: NIDDK (NIH)1

Misdiagnosis of Diabetes

Are diabetes blood test results always accurate?

All laboratory test results can vary from day to day and from test to test. Results can vary

  • within the person being tested. A person’s blood glucose levels normally move up and down depending on meals, exercise, sickness, and stress.
  • between different tests. Each test measures blood glucose levels in a different way. For example, the FPG test measures glucose that is floating free in the blood after fasting and only shows the blood glucose level at the time of the test. Repeated blood glucose tests, such as self-monitoring several times a day with a home meter, can record the natural variations of blood glucose levels during the day. The A1C test represents the amount of glucose attached to hemoglobin, so it reflects an average of all the blood glucose levels a person may experience over 3 months. The A1C test will not show day-to-day changes.

Health care providers take these variations into account when considering test results and repeat laboratory tests for confirmation. Diabetes develops over time, so even with variations in test results, health care providers can tell when overall blood glucose levels are becoming too high.

Comparing test results from different laboratories can be misleading. People should consider requesting new laboratory tests when they change health care providers, or if their health care provider’s office changes the laboratory or clinic it uses for blood testing.

Source: NIDDK (NIH)2

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Can the A1C test give false results?

Yes, for some people. The A1C test can be unreliable for diagnosing or monitoring diabetes in people with certain conditions that are known to interfere with the results. Interference should be suspected when A1C results seem very different from the results of a blood glucose test.

People of African, Mediterranean, or Southeast Asian descent, or people with family members with sickle cell anemia or a thalassemia are particularly at risk of interference. People in these groups may have a less common type of hemoglobin, known as a hemoglobin variant, that can interfere with some A1C tests. Most people with a hemoglobin variant have no symptoms and may not know that they carry this type of hemoglobin.

Not all of the A1C tests are unreliable for people with a hemoglobin variant. People with false results from one type of A1C test may need a different type of A1C test for measuring their average blood glucose level. The NGSP provides information for health care providers about which A1C tests are appropriate to use for specific hemoglobin variants at www.ngsp.org .

False A1C results may also occur in people with other problems that affect their blood or hemoglobin. For example, a falsely low A1C result can occur in people with

A falsely elevated A1C result can occur in people who

Other causes of false A1C results include

Source: NIDDK (NIH)3

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Sometimes health care professionals are unsure if diabetes is type 1 or type 2. A rare type of diabetes that can occur in babies, called monogenic diabetes, can also be mistaken for type 1 diabetes. Treatment depends on the type of diabetes, so knowing which type you have is important.

Source: NIDDK (NIH)4

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If genetic testing is not performed, people with monogenic diabetes may appear to have one of the polygenic forms of diabetes. When hyperglycemia is first detected in adulthood, type 2 is often diagnosed instead of monogenic diabetes.

Source: NIDDK (NIH)5

Undiagnosed: Diabetes

However, almost 25 percent of Americans with DM are undiagnosed, and another 57 million Americans have blood glucose levels that greatly increase their risk of developing DM in the next several years.3 Few people receive effective preventative care, which makes DM an immense and complex public health challenge.

Source: Healthy People (DHHS)6

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About 7 million Americans today have diabetes but don’t realize it. This puts them at risk for the serious complications that can arise when diabetes is left untreated.

Source: NIH News in Health (NIH)7

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More than 1 in 10 adults over age 20 has diabetes, but about 40% of them don’t know they have the disease, according to a large national survey.

Source: NIH News in Health (NIH)8

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About 2.8% of U.S. adults, a third of those who have diabetes, don’t even know they have it.

Source: NIH News in Health (NIH)9

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One of the key dangers of diabetes is that it often doesn’t display any symptoms at all, making it hard to diagnose until it’s severe.

Source: NICHD (NIH)10

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One in four people with diabetes don’t know they have the disease.

Source: NIDDK (NIH)11

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Many people have type 2 diabetes without realising. This is because symptoms don't necessarily make you feel unwell.

Source: NHS Choices UK12

Undiagnosed Stats: Diabetes

Seven million of these people are undiagnosed.1

Source: NICHD (NIH)13

Related Misdiagnosis Issues

Complex diagnosis issues or misdiagnosis may occur with conditions such as:

Misdiagnosis Articles

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  1. Source: NIDDK (NIH): niddk.nih.gov/ health-information/ diabetes/ overview/ tests-diagnosis/ a1c-test
  2. ibid.
  3. ibid.
  4. Source: NIDDK (NIH): niddk.nih.gov/ health-information/ diabetes/ overview/ tests-diagnosis
  5. Source: NIDDK (NIH): niddk.nih.gov/ health-information/ diabetes/ overview/ what-is-diabetes/ monogenic-neonatal-mellitus-mody
  6. Source: Healthy People (DHHS): healthypeople.gov/ 2020/ topics-objectives/ topic/ diabetes
  7. Source: NIH News in Health (NIH): newsinhealth.nih.gov/ issue/ apr2012/ capsule2
  8. Source: NIH News in Health (NIH): newsinhealth.nih.gov/ 2009/ March/ capsules.htm
  9. Source: NIH News in Health (NIH): newsinhealth.nih.gov/ 2006/ July/ docs/ 01features_02.htm
  10. Source: NICHD (NIH): nichd.nih.gov/ health/ topics/ diabetes/ conditioninfo/ Pages/ symptoms.aspx
  11. Source: NIDDK (NIH): niddk.nih.gov/ health-information/ diabetes
  12. Source: NHS Choices UK: nhs.uk/ conditions/ type-2-diabetes/ symptoms/ 
  13. Source: NICHD (NIH): nichd.nih.gov/ health/ topics/ diabetes/ conditioninfo/ Pages/ risk.aspx

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Note: This site is for informational purposes only and is not medical advice. See your doctor or other qualified medical professional for all your medical needs.