Misdiagnosed diabetes can lead to serious, life-threatening complications

Can diabetes be misdiagnosed? Here’s what patients should know.

Author: Sara Thompson

Published: February 4, 2025

Estimated reading time: 5 minutes

Diabetes is a condition that affects around 37 million Americans. This disease affects how your body uses glucose (sugar). High blood sugar can cause other health conditions over time, including nerve and eye damage, heart disease and kidney disease. In Type 1 diabetes and Type 2 diabetes, the diagnosis is made after confirming blood sugar is constantly high. In Type 1 diabetes, this is because the body does not produce insulin. In Type 2 diabetes, high blood sugars result when the body is no longer able to use insulin effectively. Prediabetes happens when your blood sugar is consistently above the normal range but not high enough to be considered diabetes. Prediabetes and diabetes diagnoses rely on precise blood sugar measurements and validated testing protocols. However, accuracy depends on proper testing. 

Prediabetes vs. Type 1 and Type 2 diabetes

In a healthy body, when sugar enters the bloodstream, the body releases insulin from the pancreas. The insulin unlocks the cells so they can accept the sugar as fuel. Chronically high blood sugar levels (hyperglycemia) cause damage to your veins and arteries, and over time can lead to kidney failure, loss of limbs or blindness, as well as contribute to metabolic syndrome. 

Prediabetes occurs when blood sugar levels are elevated but not high enough for a diabetes diagnosis. This is a sign that your body is having difficulty processing glucose efficiently, requiring more insulin to convert food into energy. Type 1 diabetes is an autoimmune disorder that affects the pancreas, the organ that produces the hormone insulin. People who have Type 2 diabetes either do not produce enough insulin or their bodies cannot use the insulin effectively.

How common is a prediabetes diagnosis?

According to the National Institutes of Health, more than 1 in 3 American adults over age 18 years had prediabetes in 2021. Prediabetes is more common in men (41%) than women (32%). Factors that may increase your risk for persistently abnormal high blood sugar levels include:

  • Weight: Those at a higher weight may have insulin resistance, which means the cells in the body aren’t able to accept blood glucose for energy as easily.
  • Family history: Those with a family history of diabetes, especially Type 2, have higher risk.
  • Diet: Red meat, ultra-processed foods and sugar-sweetened beverages increase your risk.

Misdiagnosed diabetes

Studies in 2023 estimated that up to 40% of adults over 30 with Type 1 diabetes may have been misdiagnosed with Type 2 diabetes. While Type 1 diabetes usually is diagnosed in children, it can develop at any age. Since adults are more likely to be diagnosed with Type 2 diabetes, doctors may mistakenly assume that any new diabetes diagnosis in older adults is Type 2 — leading to serious consequences if the wrong treatment is given.

One major risk of this misdiagnosis is diabetic ketoacidosis (DKA) a dangerous condition that happens when the body doesn’t have enough insulin. Without insulin, blood sugar levels rise too high, and the body begins to break down fat for energy, creating harmful acids called ketones. If left untreated, the buildup of ketones in the blood can lead to DKA — which requires hospitalization and intensive care. This is why getting the correct diabetes diagnosis is crucial — to prevent life-threatening complications like DKA and ensure the right treatment is given from the start. DKA most commonly happens to people with Type 1 diabetes, but it also can occur in people with Type 2 diabetes in rare cases. If an adult with Type 1 diabetes is mistakenly diagnosed with Type 2, they may not be prescribed insulin right away. This can lead to DKA, since their body can’t make insulin at all.

The American Diabetes Association specifies three diagnostic tests for prediabetes; these can  help you and your doctor determine the best course of treatment for you:

  • Fasting plasma glucose between 100 to 125 milligrams per deciliter
  • Hemoglobin A1C between 5.7% and 6.4%
  • Two-hour oral glucose tolerance test between 140 to 199 milligrams per deciliter

To prevent diabetes misdiagnosis, doctors confirm your results with a second test, either the same day or on a different day. When following this guideline, misdiagnosis is unlikely.

“There shouldn’t be any debate about how to make a diabetes diagnosis, but it is true that different tests can be different in different people,” said Lisal J. Folsom, M.D., adult and pediatric endocrinologist with Wendy Novak Diabetes Institute, a part of Norton Healthcare and Norton Children’s.

According to Dr. Folsom, who sees her adult patients at Norton Community Medical Associates – Endocrinology, it’s important to have the appropriate testing and typically confirm an abnormal result so the patient gets the right information about their health.

Treatment of prediabetes

Early detection is crucial, since 25% percent of people with a prediabetes diagnosis develop Type 2 diabetes within three to five years. 

Treatment focuses on lifestyle changes:

  • Eating whole foods and vegetables
  • Choosing whole grains
  • Limiting ultra-processed foods, simple and added sugars, and alcohol
  • Regular physical activity (150 minutes weekly)
  • Taking walks after eating meals

According to Dr. Folsom, accurate prediabetes and diabetes diagnosis enables timely intervention and better health outcomes.