What urine tests are recommended for a diabetic patient to monitor kidney function and blood sugar control?

Urine Testing in Diabetic Patients

Urine glucose testing is not recommended for routine diabetes care, but urine albumin-to-creatinine ratio should be measured at least annually to screen for diabetic kidney disease, and ketone testing (preferably blood ketones) should be performed when patients have unexplained hyperglycemia or symptoms of ketosis. 1

What Should NOT Be Tested

Urine Glucose

• Urine glucose testing is explicitly not recommended for routine care of patients with diabetes mellitus 1
• Self-monitoring of blood glucose has supplanted urine glucose testing due to well-described limitations that make blood glucose monitoring the preferred method 1
• Urine glucose testing is an inappropriate and inaccurate methodology for assessing diabetes control 2
• Blood glucose monitoring provides more accurate and timely measurement of glycemic control compared to urine testing 2

What SHOULD Be Tested in Urine

Urine Albumin-to-Creatinine Ratio (Primary Recommendation)

• Assess urinary albumin (spot urinary albumin-to-creatinine ratio) at least once yearly in patients with type 1 diabetes with duration ≥5 years, all patients with type 2 diabetes, and all patients with comorbid hypertension 1
• First morning void urine samples are preferred to minimize variability 3
• More frequent testing (every 6 months) is needed if estimated glomerular filtration rate is <60 mL/min/1.73 m² and/or albuminuria is >30 mg/g creatinine 3
• This test screens for diabetic kidney disease, a critical microvascular complication affecting morbidity and mortality 1

Urine Ketones (Selective Use Only)

• Individuals prone to ketosis (type 1 diabetes, history of diabetic ketoacidosis, or treated with SGLT2 inhibitors) should measure ketones in urine or blood if they have unexplained hyperglycemia or symptoms of ketosis (abdominal pain, nausea) 1
• When glycosuria is present during illness or stress, monitoring for ketones is important to detect early ketoacidosis 2
• However, blood ketone testing measuring β-hydroxybutyrate is strongly preferred over urine ketone testing for diagnosis and monitoring of diabetic ketoacidosis 1, 2

Critical Pitfalls to Avoid

Why Blood Ketones Are Superior to Urine Ketones

• Urine ketone tests primarily detect acetoacetate, not β-hydroxybutyrate, which is the predominant ketone in blood during diabetic ketoacidosis 4
• As diabetic ketoacidosis resolves, β-hydroxybutyrate is oxidized to acetoacetate, causing urine ketone tests to potentially increase even as the condition improves—a dangerous lag that can mislead clinicians 4
• Blood ketone determinations using the nitroprusside reaction should not be used to monitor treatment of diabetic ketoacidosis 1
• Urine ketone tests using nitroprusside-containing reagents can give false-positive results in the presence of sulfhydryl drugs, including captopril 2

Special Considerations in Pregnancy

• Up to 30% of first morning urine specimens from pregnant women show physiologic ketonuria, which does not necessarily indicate gestational diabetes 2, 5
• Pregnancy lowers the renal threshold for glucose, potentially causing glycosuria even with normal blood glucose levels 2, 5

Practical Algorithm for Urine Testing

Annual routine screening:

• Measure urine albumin-to-creatinine ratio (first morning void preferred) 1, 3

During acute illness or unexplained hyperglycemia in high-risk patients:

• Check for ketones, but prioritize blood β-hydroxybutyrate measurement over urine ketones 1, 2
• Blood β-hydroxybutyrate >3 mmol/L is diagnostic of diabetic ketoacidosis 6
• Blood β-hydroxybutyrate <1 mmol/L is insignificant 6

Never routinely test:

• Urine glucose for diabetes monitoring or control assessment 1, 2