What is the best course of action for a 50-year-old male with a 3-year history of polyuria, polydipsia, and weight loss, presenting with vomiting, abdominal pain, glycosuria, hematuria, hypokalemia, impaired renal function, and mild anemia?

Diabetic Ketoacidosis (DKA) with Acute Kidney Injury

This patient requires immediate hospitalization for treatment of diabetic ketoacidosis (DKA), which is the most likely diagnosis given the 3-year history of classic diabetes symptoms (polyuria, polydipsia, weight loss), acute presentation with vomiting and abdominal pain, glycosuria, hypokalemia, and acute kidney injury.

Immediate Diagnostic Confirmation

Measure urine or blood ketones immediately to confirm DKA, as this patient presents with the classic clinical picture: polyuria, polydipsia, weight loss, vomiting, abdominal pain, and dehydration evolving over a short timeframe 1. The presence of glycosuria (3.0) with acute symptoms strongly suggests hyperglycemic crisis 1.

• Send C-peptide, islet autoantibodies (anti-GAD, IA-2, ZnT8), and insulin levels during the acute event to distinguish autoimmune type 1 diabetes from other forms, which has critical implications for long-term management 2.
• Do not delay insulin therapy while waiting for these results—treat the DKA immediately according to standard protocols 2.
• Measure HbA1c to confirm diabetes diagnosis (≥6.5% diagnostic) and assess chronic glycemic control 3.

Acute Management Protocol

Initiate intravenous insulin therapy immediately along with aggressive fluid resuscitation and electrolyte replacement 1. The patient's hypokalemia (3.21 mmol/L) and acute kidney injury (creatinine 1.38 mg/dL, urea 60.3 mg/dL) indicate significant volume depletion from osmotic diuresis 1.

• Correct hypokalemia aggressively before or concurrent with insulin therapy, as insulin will drive potassium intracellularly and can precipitate life-threatening hypokalemia and paralysis 1.
• Monitor blood glucose and ketones frequently (every 1-2 hours initially) during treatment 1.
• Provide continuous intravenous hydration with normal saline initially, then switch to half-normal saline once hemodynamically stable 1.

Addressing the Hematuria

The hematuria (Blood +3, RBC 3-10) requires investigation after DKA stabilization, as it is not a typical feature of DKA and may indicate a concurrent urological problem or infection 1. However, this should not delay DKA treatment.

• Rule out urinary tract infection as a precipitating factor for DKA, though the urinalysis shows negative leukocytes, nitrites, and bacteria 1.
• Consider renal imaging (ultrasound or CT) after stabilization to evaluate for structural abnormalities, stones, or other causes of hematuria.

Managing Acute Kidney Injury

The acute kidney injury (AKI) is likely prerenal from volume depletion secondary to osmotic diuresis, and should improve with fluid resuscitation 1. The elevated creatinine (1.38 mg/dL) and urea (60.3 mg/dL) with hypokalemia support this diagnosis.

• Monitor renal function closely during fluid resuscitation and insulin therapy 4.
• Adjust insulin dosing based on renal function recovery, as patients with renal impairment are at increased risk of hypoglycemia 4.

Addressing the Anemia

The mild anemia (Hemoglobin 12.1 g/dL) should be investigated after DKA resolution, as it may be related to chronic disease, nutritional deficiency, or the underlying diabetes 1.

• Measure serum ferritin, transferrin saturation (TSAT), vitamin B12, and folate levels as part of the anemia workup 1.
• Consider iron supplementation if iron deficiency is confirmed (ferritin <100 ng/mL or TSAT <20%) 1.

Critical Pitfalls to Avoid

Do not assume this is hyperosmolar hyperglycemic state (HHS) instead of DKA simply because the patient is 50 years old—DKA can occur in type 2 diabetes, and the acute presentation with vomiting and abdominal pain is more consistent with DKA 1.

• Do not give oral fluids if the patient cannot tolerate them or has altered mental status—use intravenous hydration exclusively 1.
• Do not stop insulin therapy abruptly once ketones clear—continue insulin infusion until the patient can tolerate oral intake and transition to subcutaneous insulin 1.
• Do not overlook infection as a precipitating factor—the patient may be normothermic or hypothermic despite infection 1.

Long-Term Management Planning

Once DKA resolves, initiate basal-bolus insulin therapy with rapid-acting insulin (such as insulin aspart) before meals and long-acting basal insulin 4.

• If C-peptide is <0.6 ng/mL and islet autoantibodies are positive, diagnose autoimmune type 1 diabetes and counsel the patient on lifelong insulin dependence 2.
• If C-peptide is >1.8 ng/mL with negative antibodies, consider ketosis-prone type 2 diabetes, which may allow eventual insulin discontinuation after DKA resolution 2.
• Provide diabetes education on insulin administration, blood glucose monitoring, sick day management, and recognition of DKA warning signs 1.