Screening for Type 2 Diabetes and Prediabetes
Screen all adults aged 35 years and older for type 2 diabetes and prediabetes using simple blood glucose tests (fasting glucose, A1C, or oral glucose tolerance test), and screen earlier if they have overweight/obesity plus additional risk factors. 1
Who to Screen and When
The 2025 ADA guidelines emphasize that type 2 diabetes frequently remains undiagnosed for years because hyperglycemia develops gradually without causing noticeable symptoms initially 1. This presymptomatic phase is critical because:
- Duration of glycemic burden strongly predicts adverse outcomes 1
- Even undiagnosed individuals face increased macrovascular and microvascular complications 1
- Effective interventions exist to prevent progression from prediabetes to diabetes 1
Risk-Based Screening Algorithm
Use the ADA Diabetes Risk Test (available at diabetes.org/diabetes-risk-test) to identify high-risk individuals 1. If someone scores ≥5 points, they need laboratory testing immediately.
Key risk factors that warrant earlier screening include:
- Age ≥40 years (higher points for older age)
- Male sex
- History of gestational diabetes
- First-degree relative with diabetes
- Hypertension diagnosis
- Physical inactivity
- Overweight/obesity (note: Asian Americans have increased risk at 15 pounds lower body weight than other populations) 1
Why Early Detection Matters for Outcomes
The NIH Diabetes Prevention Program Outcomes Study demonstrated that preventing progression from prediabetes to diabetes resulted in lower rates of retinopathy and nephropathy 1. Similarly, UK data showed that progression from prediabetes to diabetes augmented complication risk 1.
Critical Gap in Current Practice
Despite clear benefits of screening and early diagnosis, many people in the U.S. and globally remain undiagnosed or are diagnosed late when complications have already developed 1. Research shows that awareness of prediabetes diagnosis significantly increases:
- Personal risk awareness (65% vs 45% in those without diagnosis) 2
- Receipt of risk-reduction counseling (45% vs 11%) 2
- Likelihood of taking preventive action (71% vs 52%) 2
Common Pitfalls to Avoid
Do not wait for symptoms to appear before screening. The classic diabetes symptoms (dehydration, unintentional weight loss) only occur with more severe hyperglycemia 1. By that point, the patient may have already developed complications during the undiagnosed period.
Do not assume younger patients without obvious risk factors are safe. The guidelines recommend universal screening starting at age 35, but earlier screening is warranted with any additional risk factors 1.
Do not overlook racial/ethnic disparities. Type 2 diabetes is more common in African Americans, Hispanic/Latino individuals, Native Americans, Asian Americans, and Native Hawaiians and Pacific Islanders 1. These populations warrant heightened screening vigilance.
Testing Methods
Simple, readily available tests can detect preclinical disease 1:
- Fasting plasma glucose
- A1C (89% of people with diabetes are aware of this test, with narrowing racial/ethnic disparities) 2
- Oral glucose tolerance test
The A1C test has become widely recognized and accepted, making it a practical screening tool in most clinical settings 2.