Step 4: Diagnosing diabetes

How does a doctor identify diabetes? Once symptoms appear, type 1 diabetes rarely goes undiagnosed for more than a few weeks. The most important clue is frequent urination, sometimes accompanied by feeling thirsty all the time, poor weight gain, or flu-like symptoms. If you and your doctor suspect diabetes, testing is necessary to confirm the diagnosis. There are two tests done to check for blood sugar levels.

Random blood glucose test

A random blood, or plasma, glucose test can be done at any time, regardless if you have eaten or not. A blood sample is drawn from the arm or the back of the hand and analyzed for glucose level. If the glucose level is greater than or equal to 200 mg/dL, it generally means the person has diabetes. Glucose in the urine is strong additional evidence.

However, a random blood glucose test below this level does not eliminate the possibility of diabetes.

Fasting plasma glucose (FPG) test

This is the recommended diagnostic test for diabetes. "Fasting" means that no food can be eaten for 8 - 12 hours prior to the test -- only water may be consumed. A blood sample is drawn in the same manner as the random test.

If there is any doubt that a patient truly has diabetes, two or more FPG tests may be done on different days to verify the results.

What does the FPG test reveal?

Normal fasting glucose levels are lower than 100 mg/dL. Patients whose glucose is between 100 mg/dL and 125 mg/dL have "impaired fasting glucose" and are at risk for developing type 2 diabetes, although they do not yet have diabetes.

When fasting glucose levels are 126 mg/dL or higher, the patient has diabetes. Sometimes, at the moment of diagnosis, people with type 1 diabetes have glucose levels that are "off the charts," often higher than 400 mg/dL. It is very important to see a doctor right away if you suspect diabetes.

References

American Diabetes Association. Standards of medical care in diabetes--2009. Diabetes Care. 2009 Jan;32 Suppl 1:S13-61.

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. No warranty of any kind, either expressed or implied, is made as to the accuracy, reliability, timeliness, or correctness of any translations made by a third-party service of the information provided herein into any other language.

© 1997- A.D.A.M., a business unit of Ebix, Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

All content on this site including text, images, graphics, audio, video, data, metadata, and compilations is protected by copyright and other intellectual property laws. You may view the content for personal, noncommercial use. Any other use requires prior written consent from Ebix. You may not copy, reproduce, distribute, transmit, display, publish, reverse-engineer, adapt, modify, store beyond ordinary browser caching, index, mine, scrape, or create derivative works from this content. You may not use automated tools to access or extract content, including to create embeddings, vectors, datasets, or indexes for retrieval systems. Use of any content for training, fine-tuning, calibrating, testing, evaluating, or improving AI systems of any kind is prohibited without express written consent. This includes large language models, machine learning models, neural networks, generative systems, retrieval-augmented systems, and any software that ingests content to produce outputs. Any unauthorized use of the content including AI-related use is a violation of our rights and may result in legal action, damages, and statutory penalties to the fullest extent permitted by law. Ebix reserves the right to enforce its rights through legal, technological, and contractual measures.

© 1997- All rights reserved.