Ketones Positive in Urine: Fasting or a Diabetes Emergency?

Short Answer

Ketones in urine show that the body is burning fat for energy. Mild ketones are common during prolonged fasting, religious fasting, very-low-carbohydrate (keto) eating and vomiting, and are usually harmless. According to the TEMD 2026 guideline, excess ketones in urine or blood suggest diabetic ketoacidosis (DKA) or may be a warning sign of it. If you have diabetes and ketones are found while your blood sugar is high, this requires urgent evaluation. Read your result together with the laboratory reference range on your report.

How does it appear on your report?

• Strip in a complete urinalysis: It is the "Ketone" or "KET" line. According to TEMD, the strip result is graded from -/+ to ++++.
• What does the strip measure? The urine strip measures acetoacetic acid and acetone using the nitroprusside method. It does not measure beta-hydroxybutyrate, the predominant ketone in DKA.
• Blood ketones: Listed as "Beta-hydroxybutyrate" or "β-OHB." Guidelines give thresholds in mmol/L. The Turkish Ministry of Health's Test Measurement Units document, however, lists the unit mg/dL for serum beta-hydroxybutyrate. Check the unit before comparing.
• Blood sugar unit: In Türkiye, glucose is reported in mg/dL. A mmol/L value in foreign guidelines is converted to approximately mg/dL by multiplying by 18.
• e-Nabız (Türkiye's national health record app): In the "My Lab Tests" (Tahlillerim) section, results are listed with their reference values; out-of-range values are shown in color.
• Decision limit and critical value: According to the Ministry's procedure, a fasting glucose of 126 mg/dL or higher is the decision limit for diabetes; it is marked with an asterisk (*) on the report. If glucose is 400 mg/dL or higher, the laboratory reports this to the doctor as a critical value.

Normal value and reference range

Test	Result	Possible meaning	Source
Urine strip	Negative	No ketones detected	TEMD 2026
Urine strip	-/+ or +	May be seen with prolonged fasting or very-low-carbohydrate eating	TEMD 2026
Urine strip	2+ and above	In diabetes, together with high blood sugar, one of the DKA criteria	TEMD 2026
Blood beta-hydroxybutyrate	≥3 mmol/L	One of the DKA criteria	TEMD 2026
Blood beta-hydroxybutyrate	<0.6 mmol/L	One of the criteria showing that DKA has resolved	TEMD 2026

A reference range covers 95% of healthy people; about 1 in 20 healthy people may fall slightly outside the range. Ketones alone do not make a diagnosis; they are read together with blood sugar and blood gas.

How is DKA defined? According to TEMD 2026, DKA requires plasma glucose >200 mg/dL, serum beta-hydroxybutyrate ≥3 mmol/L or urine ketones ≥2+. In addition, blood pH is ≤7.30 and bicarbonate is ≤18 mEq/L. The British JBDS 2023 guideline uses slightly different thresholds; it takes above 3.0 mmol/L for blood ketones and below 15 mmol/L for bicarbonate.

What does a high value mean?

Causes are listed from common and harmless to serious.

• Prolonged fasting and religious fasting: According to TEMD, mild ketones can be seen during fasting. According to JBDS, starvation ketosis develops over several days; the acid-base disturbance is usually mild.
• Very-low-carbohydrate (keto) eating: -/+ or + ketones in urine can be expected. TEMD emphasizes that this mild positivity may not be a disturbance due to high blood sugar.
• Vomiting and febrile illness: Starvation ketosis develops in a person who cannot eat enough. In a person with diabetes, however, acute illness can trigger DKA.
• Nausea and vomiting in pregnancy: Starvation ketosis can also be seen in pregnancy. JBDS defines ketosis of pregnancy as a condition separate from DKA.
• Alcohol: In alcohol-related ketoacidosis, blood sugar is usually normal. According to JBDS, urine ketones can be misleading in this situation; beta-hydroxybutyrate is checked in the blood.
• Diabetes and high blood sugar: This is the most important cause. If sugar is high together with ketones, DKA is possible. According to TEMD, type 1 diabetes in children and young people can present with DKA. DKA can also occur in type 2 diabetes.
• Use of SGLT2 inhibitors: These diabetes drugs increase the risk of DKA. Ketoacidosis can develop even when blood sugar is normal or slightly high; this is called euglycemic DKA.

According to TEMD 2026, about 2.6–3.2% of patients with DKA present with a blood sugar below 200 mg/dL. This may be associated with pregnancy, alcohol, prolonged fasting, liver disease and SGLT2 inhibitor use.

When read together

• Ketones + glucose in urine + high blood sugar: In diabetes, this suggests insulin deficiency. Same-day evaluation for DKA is needed.
• Ketones positive + glucose negative + history of fasting or dieting: Usually starvation ketosis. If you feel well, it is usually not an emergency.
• Ketones + SGLT2 inhibitor + normal sugar + nausea or abdominal pain: This may be euglycemic DKA. TEMD recommends measuring ketones in people taking these drugs when in doubt, even if sugar is normal.
• Ketones + low pH and bicarbonate on blood gas: This indicates ketoacidosis. Ketones alone cannot make this distinction.
• Urine ketones appear to rise during treatment: According to TEMD, with treatment, beta-hydroxybutyrate is converted to acetoacetate. This is why the urine strip can falsely show DKA as worsening.
• Ketones + protein + glucose: This suggests that diabetes is uncontrolled. Kidney monitoring is explained in the Protein in urine article.

Preparing for the test

• Tell your doctor: Mention whether you have gone without food or fasted in recent days, your diet, whether you have vomited, and your medications.
• When are ketones checked? In a person with diabetes, according to TEMD 2026, ketones should be checked when plasma glucose exceeds 300 mg/dL. In pregnancy, this threshold is 200 mg/dL.
• Other situations: Suspicious situations in people taking SGLT2 inhibitors, acute illness, trauma and surgery also require ketone measurement. Nausea, vomiting, abdominal pain, fever or an acetone smell on the breath are also reasons for measurement.
• Blood or urine? TEMD prefers blood ketone measurement, if conditions allow, for early detection of ketones and for monitoring treatment.
• Medications: Do not stop your diabetes medicines or insulin on your own. Discuss with your doctor in advance what to do on sick days.

Which doctor, which test?

• A person without diabetes who has gone without food or is dieting and feels well: Usually not an emergency. If needed, the family physician orders fasting glucose and HbA1c.
• Drinking a lot of water, frequent urination, weight loss and ketones with glucose in urine: Family physician or emergency department the same day. According to ADA 2026, with these symptoms, a random plasma glucose of 200 mg/dL or higher establishes a diagnosis of diabetes.
• Person with diabetes, high sugar and ketones positive: Diabetes team or endocrinology the same day. Blood ketones, venous blood gas and electrolytes are ordered.
• Pregnancy: Obstetrics and gynecology. In a pregnant woman with diabetes, according to JBDS, DKA can develop even with a blood sugar below 250 mg/dL (13.9 mmol/L).
• A person with diabetes planning to fast during Ramadan: TEMD 2026 recommends a medical evaluation 4–8 weeks before Ramadan.

In Türkiye

• National guideline: The TEMD (Society of Endocrinology and Metabolism of Turkey) Diabetes Mellitus Guideline 2026 defines in detail when ketone measurement should be done and the diagnostic criteria for DKA. The guideline was published in April 2026 as its 17th edition.
• Fasting and diabetes: According to TEMD, people with diabetes who fast may face the risk of high blood sugar, DKA, dehydration and severe hypoglycemia. Continuing to fast with a blood sugar below 70 mg/dL accompanied by symptoms can be life-threatening.
• SGLT2 and fasting: TEMD does not recommend fasting while taking an SGLT2 inhibitor for people using diuretics and for older people, because of the risk of dehydration.
• Critical value: According to the Ministry's procedure, in those older than 4 weeks, a glucose of 400 mg/dL or higher or 50 mg/dL or lower is a critical value. The laboratory reports this result to the doctor immediately.
• Unit difference: The national unit list gives beta-hydroxybutyrate in mg/dL, while guidelines give it in mmol/L. Check the unit when interpreting the report.

When should you seek emergency care?

• If you have diabetes and ketones are positive while your sugar is high, and you have vomiting, abdominal pain or weakness, go to the emergency department.
• If you have deep and rapid breathing, an acetone smell on your breath, confusion or excessive sleepiness, call 112 (the emergency number in Türkiye).
• If you take an SGLT2 inhibitor and have nausea, vomiting and abdominal pain, even if your sugar is normal, ask for emergency evaluation.
• If you are pregnant and cannot keep fluids down, are passing less urine, or feel unwell while having diabetes, seek care without waiting.
• If the laboratory has called you about a critical glucose value, do what you are told without delay.

Related tests

• Lab Test Guide: all tests
• How to read urinalysis results
• Protein in urine (proteinuria)
• What do leukocytes in urine mean?

What changed? (October 2026)

• New page. Consistent with the diagnostic thresholds of the TEMD Diabetes Mellitus Guideline 2026 and the ADA Standards of Care 2026.
• The JBDS 2023 guideline and the 2024 joint consensus report of the ADA, EASD and JBDS were used as the basis for the definition and differential diagnosis of DKA.

Sources

• Türkiye Endokrinoloji ve Metabolizma Derneği. Diabetes Mellitus ve Komplikasyonlarının Tanı, Tedavi ve İzlem Kılavuzu. 2026 (17th edition, April 2026). https://file.temd.org.tr/Uploads/Publications/guides/documents/diabetesmellitus2026.pdf (accessed October 2, 2026)
• Joint British Diabetes Societies for Inpatient Care (JBDS-IP). The Management of Diabetic Ketoacidosis in Adults (JBDS 02). Revised March 2023. https://abcd.care/sites/default/files/site_uploads/JBDS_Guidelines_Current/JBDS_02_DKA_Guideline_with_QR_code_March_2023.pdf (accessed October 2, 2026)
• Umpierrez GE, Davis GM, ElSayed NA et al. Hyperglycaemic crises in adults with diabetes: a consensus report. Diabetologia 2024;67:1455-1479. https://doi.org/10.1007/s00125-024-06183-8 (accessed October 2, 2026)
• American Diabetes Association Professional Practice Committee. 2. Diagnosis and Classification of Diabetes: Standards of Care in Diabetes—2026. Diabetes Care 2026;49(Suppl 1):S27-S49. https://doi.org/10.2337/dc26-S002 (accessed October 2, 2026)
• T.C. Sağlık Bakanlığı Sağlık Hizmetleri Genel Müdürlüğü. Karar Sınırı (Eşik Değer), Kritik Değer (Panik Değer) ve Ölçüm Birimlerinin Harmonizasyonu Prosedürü. 22.09.2020. https://dosyamerkez.saglik.gov.tr/Eklenti/15143/0/karar-siniri-esik-deger-kriek42009846pdf.pdf (accessed October 2, 2026)
• T.C. Sağlık Bakanlığı Sağlık Hizmetleri Genel Müdürlüğü. Test Ölçüm Birimleri, Versiyon 2. 15.09.2021. https://dosyamerkez.saglik.gov.tr/Eklenti/41467/0/test-olcum-birimleri-versiyon-2-pdfpdf.pdf (accessed October 2, 2026)
• T.C. Sağlık Bakanlığı. e-Nabız Kullanım Kılavuzu V2.1. 31.05.2025. https://enabiz.gov.tr/document/User_Manual.pdf (accessed October 2, 2026)