What ICD-10 codes and screening tests are recommended for diagnosing diabetes in patients with symptoms or risk factors, such as polyuria, polydipsia, or unexplained weight loss, and how often should screening be performed?

ICD-10 Codes and Screening for Diabetes

For diabetes screening, use Z13.1 (encounter for screening for diabetes mellitus) as the primary ICD-10 code, and perform screening with fasting plasma glucose (FPG ≥126 mg/dL) or A1C (≥6.5%) in adults aged 35-45 years or earlier if overweight/obese with risk factors, repeating every 3 years if normal. 1, 2, 3

Primary ICD-10 Screening Code

• Z13.1 is the appropriate ICD-10 code for "encounter for screening for diabetes mellitus" 4
• This code should be used when ordering screening tests in asymptomatic patients or those with risk factors but no confirmed diagnosis 4

Who Should Be Screened

Age-Based Screening

• Begin screening at age 35 years for all adults regardless of risk factors 3
• Alternative guideline recommends starting at age 45 years for those without additional risk factors 1, 2, 5
• Screen at age 40-70 years if BMI ≥25 kg/m² 2

Risk Factor-Based Screening (Screen Earlier Than Age 35-45)

• BMI ≥25 kg/m² (≥23 kg/m² for Asian Americans) with any additional risk factor 1, 5
• First-degree relative with diabetes 1, 5
• High-risk ethnicity: African American, Latino, Native American, Asian American, Pacific Islander 1
• Hypertension (≥140/90 mmHg or on antihypertensive therapy) 1
• HDL cholesterol <35 mg/dL and/or triglycerides >250 mg/dL 1
• Physical inactivity 1
• Women with prior gestational diabetes or delivered baby >9 lb 1
• Polycystic ovary syndrome (PCOS) 1
• Previous impaired fasting glucose (IFG) or impaired glucose tolerance (IGT) 1
• History of cardiovascular disease 1
• Sustained blood pressure >135/80 mmHg 1

Recommended Screening Tests

First-Line Tests

• Fasting plasma glucose (FPG): Most practical, reproducible, and cost-effective screening test 1
• A1C: Convenient alternative, no fasting required 1
• Both tests have similar predictive value for microvascular complications 1

Diagnostic Thresholds (Requires Confirmation on Separate Day)

• FPG ≥126 mg/dL (7.0 mmol/L) after 8-hour fast 1, 6
• A1C ≥6.5% on two separate occasions 1, 6
• Random plasma glucose ≥200 mg/dL (11.1 mmol/L) with classic symptoms (polyuria, polydipsia, unexplained weight loss) 1, 6
• 2-hour oral glucose tolerance test (OGTT) ≥200 mg/dL (11.1 mmol/L) with 75-g glucose load 1

When Single Test Suffices for Diagnosis

• Random plasma glucose ≥200 mg/dL with unequivocal hyperglycemic symptoms does not require confirmation 1
• Classic symptoms include polyuria, polydipsia, weight loss, blurred vision, and fatigue 1

Screening Frequency

• Every 3 years if initial screening is normal 1, 2, 5
• More frequently (annually or more often) for patients with borderline results or multiple risk factors 1, 3
• Consider shorter intervals for patients with A1C 5.7-6.4% (prediabetes category) 1

Pre-Diabetes Categories (Increased Risk)

• Impaired fasting glucose (IFG): FPG 100-125 mg/dL (5.6-6.9 mmol/L) 1
• Impaired glucose tolerance (IGT): 2-hour OGTT 140-199 mg/dL (7.8-11.0 mmol/L) 1
• A1C 5.7-6.4% 1
• These patients require counseling on weight loss and exercise to reduce diabetes risk 1

Common Pitfalls to Avoid

• Do not wait until age 45 for overweight/obese patients with risk factors—screen immediately 5
• Always confirm abnormal results with repeat testing on a separate day unless patient has unequivocal hyperglycemic symptoms 1
• Do not rely on random blood glucose alone for screening—sensitivity is only 39-55% 1
• Avoid community screening outside healthcare settings—ensures proper follow-up and appropriate targeting of high-risk populations 1
• Do not use A1C alone to rule out diabetes—values <6.5% do not exclude diabetes if FPG or OGTT are elevated 1

Additional ICD-10 Codes for Confirmed Diagnosis

Once diabetes is diagnosed, use appropriate diagnostic codes:

• E11.9: Type 2 diabetes without complications
• E10.9: Type 1 diabetes without complications
• Add specific complication codes as applicable 4