What is prediabetes?

Prediabetes: Definition and Clinical Significance

Prediabetes is a metabolic condition characterized by blood glucose levels that are higher than normal but not yet high enough to be diagnosed as diabetes, indicating increased risk for developing type 2 diabetes and cardiovascular disease. 1

Definition and Diagnostic Criteria

Prediabetes is diagnosed when one or more of the following criteria are met:

• Impaired Fasting Glucose (IFG): Fasting plasma glucose levels of 100-125 mg/dL (5.6-6.9 mmol/L)
• Impaired Glucose Tolerance (IGT): 2-hour plasma glucose levels during 75-g oral glucose tolerance test of 140-199 mg/dL (7.8-11.0 mmol/L)
• Hemoglobin A1C (HbA1C): 5.7-6.4% (39-47 mmol/mol) 1

It's important to note that the World Health Organization (WHO) defines the IFG cutoff at 110 mg/dL (6.1 mmol/L), which differs from the American Diabetes Association criteria. 1

Epidemiology and Risk

Prediabetes affects approximately:

• 1 in 3 adults in the US
• 720 million individuals worldwide 2

The progression rate from prediabetes to diabetes is significant:

• Approximately 10% of people with prediabetes progress to diabetes each year in the US 2
• The risk increases disproportionately as A1C rises 1

Risk Factors for Prediabetes

Individuals at higher risk for prediabetes include those who are:

• Overweight or obese (BMI ≥25 kg/m² or ≥23 kg/m² in Asian Americans)
• Physically inactive
• Have a first-degree relative with diabetes
• Belong to high-risk racial/ethnic groups (e.g., African American, Latino, Native American, Asian American, Pacific Islander)
• Have history of cardiovascular disease
• Have hypertension (≥130/80 mmHg or on therapy)
• Have HDL cholesterol <35 mg/dL and/or triglycerides >250 mg/dL
• Women with polycystic ovary syndrome
• Individuals with conditions associated with insulin resistance (e.g., severe obesity, acanthosis nigricans) 1

Health Implications

Prediabetes is not merely a risk factor for diabetes but carries its own health risks:

• Increased mortality (excess absolute risk of 7.36 per 10,000 person-years)
• Increased cardiovascular events (excess absolute risk of 8.75 per 10,000 person-years) 2
• Associated with microvascular and macrovascular disease 3

Screening Recommendations

The American Diabetes Association recommends:

1. Testing should begin at age 35 years for all individuals
2. Earlier testing for those who are overweight/obese with additional risk factors
3. Testing every 3 years if results are normal
4. Annual testing for those with prediabetes
5. Testing every 3 years (minimum) for women with history of gestational diabetes 1

Pathophysiology

Prediabetes involves:

• Insulin resistance
• Insulin secretory dysfunction
• Both abnormalities are present before diabetes develops 4

Clinical Significance

Understanding prediabetes is crucial because:

1. It identifies individuals at high risk for developing diabetes
2. It presents an opportunity for intervention before diabetes develops
3. It signals increased cardiovascular and mortality risk independent of progression to diabetes
4. Interventions at this stage can be highly effective in preventing or delaying diabetes 2, 5

Common Pitfalls in Prediabetes Management

1. Failing to recognize prediabetes as a serious health condition rather than just a risk factor
2. Using inconsistent diagnostic criteria (multiple definitions exist)
3. Not screening high-risk individuals according to guidelines
4. Missing opportunities for intervention in this critical window
5. Overlooking the cardiovascular and mortality risks associated with prediabetes itself

Prediabetes should be viewed as an opportunity for intervention rather than simply a "pre-disease" state, as effective treatments exist that can significantly reduce progression to diabetes and improve cardiovascular outcomes.