How Is Diabetes Diagnosed & What Tests Are Used?

Understanding diabetes

diabetes tests

how is diabetes diagnosed

how to diagnose diabetes

Written by:Dr. Ergin

Publish Date:May 15, 2022

WHAT IS DIABETES?

Diabetes is defined as a condition in which blood sugar levels are consistently high. The reasons for this differ from one person to the next. This concept appeals to me since it prevents labeling someone "diabetic" simply because they have a high blood sugar level after receiving a cortisone shot, for example.

It doesn't imply you don't have difficulties controlling sugar in your body if your blood sugar rises after one of these steroid shots but remains normal at other times. In fact, you're probably having some trouble with this. However, it does not always imply that you have diabetes. Today we will talk about how is diabetes diagnosed, and what diabetes tests are used to establish the diagnosis.

The term "diabetes" is mostly a numerical issue. It indicates that your blood glucose levels are abnormally high, but the causes differ depending on the type of diabetes you have. I'll go into greater detail regarding the many types of diabetes that we are aware of. Whatever type you have, your blood sugar levels are used to diagnose it more than anything else.

In terms of the numbers, you can have multiple tests done in your doctor's office or have another screening test done to see whether you have diabetes. Your doctor can tell you whether or not you have the disease based on the numbers. Let's have a look at the many tests that are used to make an official diabetes diagnosis. To confirm your diabetes, two out of three tests must be positive.

Diagnostic Tests For Diabetes and How To Interpret Them

1. Fasting blood sugar:

This is a standard diabetes screening test. It necessitates an overnight fast (nothing but water and most medications for at least 8 hours). For this test, your blood will be drawn once. The following are the current test definitions:

« Blood sugar levels below 100 mg/dL (5.55 mmol/l) are considered normal.

« Prediabetes—a blood sugar level of 100 to 125 mg/dL (5.55 – 6.9375 mmol/l)

« Diabetes: 125 mg/dL (6.9375 mmol/l) or higher

« For recognized diabetics, the normal range is 80 to 130 mg/dL (4.44 mmol/l – 7.215 mmol/l).

It's usually a simple affair to reconfirm the number or confirm the diagnosis with another test if it's near to the dividing line between two levels.

2. Glycosylated hemoglobin (HbA1c):

HbA1c t basically measures how "sugar-coated" your red blood cells have been recently. Because red blood cells last about 120 days in your body, you can do this test at any time of day without fasting and find out how high your average blood sugar was in the previous three months. This is because glucose adheres to red blood cells for the rest of their lives. This number is used to make the following diagnoses:

« Average (less than 5.7%)

« Prediabetes—between 5.7 and 6.4 percent of the population

« Diabetes (6.5%) or greater

For various reasons, this is a wonderful test. 1) There is no need to fast. 2) In order to offer a beautiful "average" blood sugar value, it ignores isolated highs and lows. 3) It's a fantastic way to see if any diabetes treatments you've tried have been successful. As a result, it can be done as frequently as every three months in diabetics.

3. GTT (Glucose Tolerance Testing):

This is a test that is performed at the doctor's office. You must fast overnight and then consume a glucose-containing syrup containing precisely 75 grams of glucose. Two hours later, your blood sugar is checked. The following are the outcomes:

« Healthy—less than 140 mg/dL (7.77 mmol/l)

« Prediabetes (7.77 mmol/l – 11.04 mmol/l)—140 to 199 mg/dL

« Diabetes with a blood sugar level of 200 mg/dL or higher (11.1 mmol/l)

Note that a blood sugar level of 200 mg/dl (11.1 mmol/l) at any point during the test confirms diabetes.

Is it possible to test and diagnose diabetes using a fingerstick?

To screen and diagnose diabetes, fasting blood sugar, 2-hour post-meal blood sugar, and HbA1C tests are required. However, if you suspect you have diabetes and your blood sugar level isn't normal, you should avoid self-diagnosing with a fingerstick with a home blood glucose meter. There are standards that laboratories use to diagnose diabetes that a fingerstick will not provide.

As a result, you should request a laboratory test from your doctor's office. However, if you checked your blood sugar with someone else's meter and found a high blood sugar level of 200 mg/dL or more (11.1 mmol/l), it could mean you have diabetes. In that scenario, I strongly advise you to contact a doctor as soon as possible.

It's also crucial to speak with your Endocrinologist about how frequently you should monitor your blood sugars, such as fasting blood sugar or the HbA1C test. Also, know what your results signify and what your HbA1C and blood sugar targets are.

If your findings are above "normal" and you have never been diagnosed with diabetes, prediabetes, or insulin resistance, your endocrinologist may prescribe additional tests.

How is Diabetes Treated?

Weight loss, a balanced diabetic eating plan, and regular exercise may all be part of the treatment approach. When lifestyle adjustments fail, you may need to start using diabetic drugs, such as insulin, though this is usually the final choice.

If you've been diagnosed with diabetes, I recommend obtaining some training on how to check your blood sugars with a meter or a continuous glucose monitor (CGM) like the Dexcom or Freestyle Libre systems. Also, consult with your doctor on a treatment plan that is right for you.

Other sugar-related tests: A random blood sugar test taken at any time of day, regardless of whether or not you've eaten, can also be beneficial. Diabetes is defined as a blood sugar level greater than 200 mg/dL (11.1 mmol/l) at any time, especially if there are symptoms of the disease. Some patients will discover that they have "sugar in their urine," however this is a poor diabetes test.

Having this result, however, may signal that more testing is required.

Tests to diagnose diabetes type: You can undergo some testing to discover the type of diabetes you have. These tests are not required for everyone, but they can be beneficial in some cases. The C-peptide test is used to determine whether you are producing insulin.

C-peptide is a tiny protein fragment that breaks off after the pancreas produces insulin but before it can be "activated." If your results are low, you most likely have type I diabetes. You most likely have type 2 diabetes if this result is high or even normal.

What is C-peptide Test and What Is The Normal Range?

C-peptide has a normal range of 0.5 to 2.0 nanograms per milliliter, while reference ranges vary by laboratory. Furthermore, the results of a C-peptide test should be evaluated in light of the blood glucose levels at the time of the test. I would strongly advise having your C-peptide test values interpreted by an endocrinologist.

Another test for specific kinds of diabetes is antibody screening. The following are a few examples:

Antibodies against the cytoplasm of islet cells (for type 1 diabetes or latent autoimmune diabetes, also called LADA)

Antibodies against glutamic acid decarboxylase

Antibodies to IA-2 alpha

Antibodies to IA-2 beta

Type 1 diabetes and type 1.5 diabetes (LADA), as you shall learn, are true immune-related illnesses in which your immune system produces antibodies that damage insulin-producing cells (beta cells). Type 2 diabetes, for example, does not include these immune molecules. This is why antibody testing, particularly at the time of diagnosis, can be beneficial.

Antibody testing, on the other hand, is not required for all diabetic patients. Patients who are candidates for these antibody tests are those who are younger or who are not necessarily obese. For example, a 45-year-old male who is 5'10" and 170 pounds (not overweight) with high blood sugars and positive antibodies in his blood may have type 1.5 diabetes.

A 10-year-old girl with obesity, on the other hand, may develop type 2 diabetes rather than type I. I would order antibody testing to rule out type 1 diabetes due to her early age.

Almost every day, I see patients who have previously been misdiagnosed. Type 2 diabetes is the most common misdiagnosis, while the patient actually has type 1.5 diabetes.

Is Diabetes Caused By Having Too Much or Too Little Insulin?

This is a trick question because diabetes isn't defined by the amount of insulin you have, as you've probably figured out. It's understandable that some persons with diabetes have little or no insulin. Others have a lot of this hormone, but they have diabetes because they can't use it properly (an issue known as insulin resistance).

In summary,

In order to diagnose diabetes;

A blood sample will be drawn at random and a blood sugar level of 200 milligrams per deciliter (mg/dL) — 11.1 millimoles per liter (mmol/L) — or higher, regardless of when you last ate, indicates diabetes.

Fasting blood sugar level test Following an overnight fast, a blood sample will be taken. Fasting blood sugar levels of less than 100 mg/dL (5.6 mmol/L) are considered normal. Prediabetes is defined as fasting blood sugar levels ranging from 100 to 125 mg/dL (5.6 to 6.9 mmol/L). Diabetes is diagnosed when your blood sugar level is 126 mg/dL (7 mmol/L) or higher on two separate tests.

Test for oral glucose tolerance. You fast overnight for this test, and your fasting blood sugar level is measured. Then you drink a sugary liquid and your blood sugar levels are checked every two hours for the next two hours.

Normal blood sugar levels are less than 140 mg/dL (7.8 mmol/L). After two hours, a reading of more than 200 mg/dL (11.1 mmol/L) indicates diabetes. A blood sugar level of 140 to 199 mg/dL (7.8 mmol/L to 11.0 mmol/L) indicates prediabetes.

If you have type 1 diabetes, your urine will be tested for the presence of a byproduct produced when muscle and fat tissue are used for energy because the body lacks enough insulin to use the available glucose (ketones). Your doctor will also most likely run a test to see if you have autoantibodies, which are destructive immune system cells associated with type 1 diabetes.

About the author

Dr. Ahmet Ergin is the author of The Ultimate Diabetes Book and the Founder of the SugarMD youtube channel. He practices in Port Saint Lucie, FL as an endocrinologist physician.

Written By Dr. Ahmet Ergin

457 total articles

Meet Dr. Ahmet Ergin, a highly skilled and dedicated endocrinologist with a passion for diabetes care. Dr. Ergin earned his medical degree with honors from Marmara University in Istanbul. He completed internal medicine residency and endocrinology fellowship at Cleveland Clinic. Dr. Ergin is board-certified in Internal Medicine, Endocrinology, Diabetes, and Metabolism due to his vast medical expertise. He's a certified diabetes educator, author of “The Ultimate Diabetes Book,” and founder of “the SugarMD YouTube channel.” Dr. Ergin offers exceptional diabetes care to his patients in Port Saint Lucie, FL, helping them manage effectively. For a closer look into his insights and experiences, connect with Dr. Ahmet Ergin on LinkedIn, Instagram, and YouTube.”

Disclaimer: These statements have not been evaluated by the Food and Drug Administration. Information on this website isn't intended to treat, cure or prevent any disease. Discuss with your doctor and do not self-treat.