Prediabetes Diagnosis


When the blood sugar or blood glucose levels are quite high, the condition is known as diabetes. When the blood glucose levels are higher than normal but not high enough for the diagnosis of diabetes, the condition is recognized as ‘prediabetes’. It is also known as borderline diabetes. It is confirmed after performing a fasting plasma glucose test (FPG) or an oral glucose tolerance test (OGTT). A random plasma glucose test is used to measure blood glucose, and one doesn’t need to fast for this test. It means that it can be taken even if the person has just had something to eat or drink. This test, after examining the specific symptoms, is used to diagnose diabetes but not borderline diabetes.

Prediabetes Diagnostic Criteria

The fasting plasma glucose levels, according to the WHO, should be between 110 mg/dl to 125 mg/dl, and according to the ADA, it should be between 100 mg/dl to 125 mg/dl for a prediabetes diagnosis. Fasting blood sugar test is most reliable when it is done in the morning after fasting for at least 8 hours. Having an impaired fasting glucose (IFG) means that you have an increased risk of developing type 2 diabetes but do not have it as yet. A fasting blood glucose of greater than or equal to 126 mg/dl, noticed again in the test on some other day, is indicative of diabetes.

Plasma Glucose Result Diagnosis
99 mg/dL or below Normal
100 to 125 mg/dL (5.6 to 6.9 mmol/L) Impaired fasting glucose (prediabetes)
126 mg/dL (7.0 mmol/L) and above in more than one test result Diabetes

Experts say that OGTT is more sensitive than the FPG test for diagnosing prediabetes, but it is less convenient to administer. OGTT also requires a fasting for 8 hours. The plasma glucose level is measured twice, immediately before and 2 hours after a person drinks a liquid containing 75 grams of glucose dissolved in water. If the blood sugar level is between 140 and 199 mg/dl, 2 hours after drinking the liquid, prediabetes is confirmed. This condition is known as impaired glucose tolerance (IGT). An individual having IGT or IFG has an increased risk of developing type 2 diabetes but does not have it as yet. A two-hour glucose level of 200 mg/dl or above, noticed again when the test is repeated on another day, confirms that the person has acquired diabetes.

2-Hour Plasma Glucose Result Diagnosis
139 mg/dL or below Normal
140 to 199 mg/dL Impaired glucose tolerance (prediabetes)
200 mg/dL and above in more than one test result Diabetes

Prediabetes Diagnosis with A1c Test

The ADA has recently included the A1c test for detecting diabetes and prediabetes. A1c provides an additional option to confirm the diagnosis of prediabetes. The test may not be appropriate in certain situations, such as heavy bleeding, pregnancy, and certain types of anemia. This test informs us about what percentage of our hemoglobin has glucose sticking to it. The A1c test is also known as glycated hemoglobin or HbA1c test, and it provides a picture of the average blood sugar control for the past 2 to 3 months. According to the new A1c guidelines, an A1c between 5.7% – 6.4% (39 – 46 mmol/mol) is a sign of prediabetes, whereas an A1c level of 6.5% (47 mmol/mol) or higher indicates diabetes. People having A1c levels above 6%, need intensive interventions and vigilant follow-up.

Type 1 Diabetes Diagnosis

Type 1 diabetes is also known as juvenile diabetes, because it is usually diagnosed in children, teenagers, and young adults. In type 1 diabetes, the body’s immune system attacks and destroys the pancreatic cells specialized to make insulin (beta cells), as a result of which the pancreas is not capable of producing enough insulin. Therefore, high blood glucose levels are noticed. All types of diabetes are diagnosed by checking the blood glucose levels.

Type 2 Diabetes Diagnosis

Type 2 diabetes is the most common form of diabetes. People may have type 2 diabetes at any age, even during childhood. This disease usually begins with insulin resistance, a condition in which the muscle, liver, and fat cells do not use insulin properly. Therefore, the body requires more insulin to facilitate the entry of glucose into the cells. This glucose is needed for energy generation. In the initial stages, the pancreas produces more insulin to match the increasing demand of the body. But afterwards, it loses its ability to produce enough insulin in response to meals.

Increased urination, increased thirst, and unexplained weight loss are the main symptoms of diabetes. People aged 45 or older should regularly check for prediabetes or diabetes. Those who are younger than 45 should consider testing if they are overweight (slightly or extremely) and have one or more of the risk factors, such as having a parent, brother, or sister with diabetes, being physically inactive, having a history of cardiovascular diseases, etc.

All Medicare claims require a valid ICD-9-CM diagnosis code and a CPT procedure code in order to be reimbursed. ICD-9-CM codes are used to describe diseases, injuries, symptoms, and conditions, whereas CPT codes indicate medical and surgical services performed by health care providers. 790.29 is the ICD-9-CM medical code that can be used as a prediabetes diagnosis code on a reimbursement claim. Those diagnosed with prediabetes should remember that regular exercise and a low-fat or low-calorie diet can help delay or prevent type 2 diabetes.


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