How do you detect ketosis in a type 2 diabetic patient with a history of cardiovascular disease or impaired renal function?

How to Detect Ketosis in Type 2 Diabetic Patients

Measure serum β-hydroxybutyrate directly rather than relying on urine ketones, as this provides the most accurate assessment of ketosis, particularly in patients with cardiovascular disease or impaired renal function who may be on SGLT2 inhibitors. 1

Primary Detection Methods

Blood Ketone Testing (Preferred)

• Serum β-hydroxybutyrate measurement is the gold standard for detecting ketosis in type 2 diabetes, offering superior accuracy compared to urine testing 1
• Blood ketone meters provide quantitative results that directly reflect the metabolic state
• This method is especially critical when SGLT2 inhibitors are being used, as these medications can cause euglycemic ketoacidosis where glucose levels appear reassuringly normal while dangerous ketoacidosis progresses 2, 1

Urine Ketone Testing (Alternative)

• Urine ketone strips detect acetoacetate and acetone but are less accurate than blood testing 1
• Urine testing may be falsely negative in patients with impaired renal function due to decreased ketone clearance 2
• Despite limitations, urine ketone monitoring can be useful for home screening when patients feel unwell 1, 3

Diagnostic Criteria for Diabetic Ketoacidosis

When ketosis is detected, confirm DKA using the triad of criteria 2, 4, 5:

• Blood glucose >250 mg/dL (though euglycemic DKA can occur with near-normal glucose on SGLT2 inhibitors) 2, 1
• Arterial pH <7.3 2, 4
• Serum bicarbonate <18 mEq/L 2, 4
• Elevated serum ketones (β-hydroxybutyrate and acetoacetate) 2
• High anion gap metabolic acidosis 2, 5

Clinical Scenarios Requiring Ketone Monitoring

Patients on SGLT2 Inhibitors

• High clinical suspicion is mandatory in patients presenting with nausea, vomiting, abdominal pain, dyspnea, or generalized weakness, even when glucose appears normal 1
• SGLT2 inhibitors increase ketone production through multiple mechanisms: reduced insulin doses, increased glucagon leading to lipolysis, and decreased renal clearance of ketones 2
• The most dangerous error is dismissing ketoacidosis because glucose is normal—SGLT2 inhibitors cause glycosuria that prevents glucose accumulation while ketoacidosis progresses unchecked 1

High-Risk Situations Requiring Immediate Testing

• Acute illness, infection, or surgical stress 1, 6
• Reduced oral intake, vomiting, or dehydration 1, 3
• Recent insulin dose reductions or discontinuation 2, 1
• Periods of prolonged fasting or carbohydrate restriction 2

Monitoring Protocol

Frequency of Testing

• Check blood or urine ketones when feeling unwell 1, 3
• During suspected DKA, monitor serum β-hydroxybutyrate every 2-4 hours until resolution 1
• Blood glucose should be checked every 1-2 hours until stable 1
• Electrolytes, BUN, creatinine, and venous pH require monitoring every 2-4 hours 1

Laboratory Panel for Complete Assessment

• Serum glucose 2, 4
• Arterial blood gases (pH) 2, 4
• Serum bicarbonate 2, 4
• Serum ketones (β-hydroxybutyrate preferred) 1
• Complete metabolic panel including electrolytes 2, 4
• Anion gap calculation 2, 4
• Blood urea nitrogen and creatinine (especially important with renal impairment) 2, 4

Patient Education for Prevention

Sick Day Protocol

• Pause SGLT2 inhibitors during acute illness, surgery, or periods of reduced oral intake 1, 3
• Never discontinue insulin during illness—maintain at least low-dose insulin if on combination therapy 1, 3
• Provide blood or urine ketone monitoring supplies for home use 1, 3

Warning Signs Requiring Immediate Medical Attention

• Nausea, vomiting, or abdominal pain 1, 3
• Dyspnea or generalized weakness 1
• Persistent symptoms despite appropriate dietary education 2

Critical Pitfalls to Avoid

• Do not rely solely on glucose levels in patients on SGLT2 inhibitors—euglycemic ketoacidosis can occur with glucose <250 mg/dL 2, 1
• Do not use urine ketones alone in patients with impaired renal function, as decreased renal clearance affects accuracy 2, 1
• Do not dismiss symptoms when glucose appears reassuring—check ketones directly 1
• Starvation ketosis typically does not lower serum bicarbonate below 18 mEq/L, distinguishing it from DKA 2