Prediabetes
Prediabetes is a state in which blood glucose is above the normal range but does not meet diagnostic criteria for diabetes. It is an important risk marker for future type 2 diabetes and cardiovascular disease, and it creates an opportunity to reduce risk before diabetes develops.
At a glance
Quick facts
- Category
- Intermediate hyperglycemia
- Typical symptoms
- Usually none
- A1C range
- 5.7–6.4%
- Fasting glucose
- 100–125 mg/dL
- 2-hour OGTT
- 140–199 mg/dL
- Main goal
- Prevent or delay type 2 diabetes
Dr. Augustine Chinemerem Anadu
Consultant Family Physician · University of Calabar Teaching Hospital
Reviewed for clinical accuracy, practical wording and general-medicine context.
Names & terminology
How this entity may be named or searched
- Prediabetes
- An umbrella term for glucose or A1C values above normal but below the diabetes range.
- IFG
- Impaired fasting glucose: fasting plasma glucose 100–125 mg/dL (5.6–6.9 mmol/L) in ADA criteria.
- IGT
- Impaired glucose tolerance: 2-hour plasma glucose 140–199 mg/dL (7.8–11.0 mmol/L) during a 75-g OGTT.
Structured entity profile
Clinical profile
Overview
Prediabetes describes glucose values that are higher than normal but below the diagnostic range for diabetes. ADA 2026 defines prediabetes by an A1C of 5.7–6.4%, fasting plasma glucose of 100–125 mg/dL (5.6–6.9 mmol/L), or a 2-hour plasma glucose of 140–199 mg/dL (7.8–11.0 mmol/L) during a 75-g oral glucose tolerance test. [1]
These tests do not always identify exactly the same people because they measure different aspects of glucose metabolism. Prediabetes should therefore be interpreted in the context of the test used, the person’s risk factors and conditions that can affect test accuracy. [1]
Symptoms and warning signs
Prediabetes usually causes no clear symptoms. Symptoms such as marked thirst, frequent urination, unexplained weight loss or blurred vision can occur with more significant hyperglycemia and should prompt testing for diabetes rather than being assumed to represent uncomplicated prediabetes. [1]
SYMPTOM MATRIX
Prediabetes is usually detected by testing rather than symptoms
Risk factors and laboratory results are more useful than symptoms for identifying prediabetes.
- No noticeable symptoms
- Abnormal A1C or plasma glucose on testing
- Often found during routine screening
- May coexist with overweight or obesity
- Hypertension
- High triglycerides or low HDL cholesterol
- Polycystic ovary syndrome
- History of gestational diabetes
- Family history of diabetes
- Marked thirst and frequent urination
- Unexplained weight loss
- Persistent blurred vision
- Symptoms with very high glucose readings
Symptoms of significant hyperglycemia require assessment for diabetes or acute metabolic illness rather than a prediabetes label alone.
Diagnosis
A1C, fasting plasma glucose and the 2-hour value during a 75-g oral glucose tolerance test can all be used to identify prediabetes. Each test has limitations, and A1C can be less reliable when red-cell turnover or some hemoglobin variants affect the measurement. [1]
Prediabetes is also a signal to assess overall cardiometabolic risk, including blood pressure, lipids, weight, smoking and other factors that may change cardiovascular risk. ADA recommends monitoring people with prediabetes for progression to diabetes at least annually, with frequency individualized by risk. [1] [2]
Diagnostic pathway
Use validated glucose tests and interpret them in context
Different tests can identify overlapping but not identical groups of people.
The glucose and A1C ranges shown here are ADA 2026 criteria for nonpregnant individuals; pregnancy uses different diagnostic frameworks. Source [1]
Who is at higher risk of progression?
Risk of type 2 diabetes is not the same for everyone with prediabetes. Higher-risk features include greater obesity, higher glucose values within the prediabetes range, younger age with substantial metabolic risk, prior gestational diabetes and combinations of hypertension and dyslipidemia. ADA recommends using the overall risk profile to guide prevention intensity. [2]
Treatment and management
The core intervention is a structured lifestyle program aimed at sustainable weight reduction, healthy eating and regular physical activity. ADA 2026 recommends referral of people with overweight or obesity at high risk for type 2 diabetes to an intensive diabetes prevention program, with a goal of maintaining at least 5–7% weight reduction when appropriate. [2]
For people at particularly high metabolic risk, including some with marked obesity, I discuss whether metformin is appropriate rather than relying on observation alone; the decision still needs to be individualized.
Metformin can be considered for selected adults at particularly high risk rather than for every person with prediabetes. The decision depends on age, BMI, glucose values, previous gestational diabetes and the overall risk-benefit context. [2]
Treatment & care hub
Reduce progression risk and treat the whole cardiometabolic profile
Prevention is broader than glucose alone.
Use an intensive prevention approach
Nutrition, physical activity and sustainable weight management have the strongest evidence base.
Track glycemia over time
Repeat A1C or plasma glucose testing according to risk and clinical context.
Consider metformin when appropriate
Medication is not automatic; it is considered for people with higher progression risk.
Address blood pressure and lipids
Prediabetes commonly clusters with other cardiovascular risk factors.
Metformin and prediabetes
DiseasesConditions has a separate evidence profile for this specific medicine–condition relationship: Metformin for Prediabetes: What Does the Evidence Show?
United States estimate
Prediabetes is common and often unrecognized
CDC estimates show a large population at increased risk before type 2 diabetes is diagnosed.
Common questions
Frequently asked questions
No. Glucose levels are above normal but below the diagnostic range for diabetes.
Usually not. Clear symptoms of hyperglycemia should prompt testing for diabetes or another cause.
Glucose levels can improve, especially with sustained lifestyle changes and weight reduction when appropriate, but ongoing monitoring is still important.
No. Metformin is considered for selected people at higher risk rather than used automatically for everyone.
ADA 2026 recommends monitoring for progression to diabetes at least annually, with frequency adjusted to individual risk.
Sources
- American Diabetes Association — Diagnosis and Classification of Diabetes: Standards of Care in Diabetes—2026
- American Diabetes Association — Prevention or Delay of Diabetes and Associated Comorbidities: Standards of Care in Diabetes—2026
- CDC — Diabetes: A US Report Card
This article is based on trusted medical sources and has undergone clinician review. It is not a substitute for personalized medical advice.
A1C can be less reliable when red-cell turnover or hemoglobin variants affect the result. In those situations I place more weight on plasma glucose testing and the wider clinical context.