Section 12: Diabetic Ketoacidosis in Cats

DKA is a life-threatening complication of DM. Although DKA is more commonly seen in naive diabetic patients,¹ it may occur in treated diabetics. Concurrent diseases (e.g., pancreatitis, urinary tract or other infections, hypercortisolism, and renal disease) often precipitate DKA. Insulin deficiency leads to reduced glucose transport into cells and increased release of free fatty acids, resulting in increased hepatic ketone production, acidosis, electrolyte imbalances, and dehydration.

Diagnosis of DKA relies on identifying compatible clinical signs in sick diabetic patients and confirming ketosis and acidosis. If acid/base status measurement is not available, treat sick, ketotic diabetic patients as DKA patients. Clinically well diabetic cats occasionally have ketonuria, so in the absence of consistent biochemical abnormalities and clinical signs of DKA (e.g., poor appetite, vomiting), do not treat them as DKA patients.

Measure ketones with a point-of-care handheld ketone meter (these measure BHB) or with standard urine test strips (these measure acetoacetate). Both may be helpful, but BHB more accurately identifies earlier stages of ketoacidosis.² Clinical laboratories also measure BHB if a point-of-care ketone meter is not an option, however, rapid identification of ketone elevation is important. Because of  the affordability and ease of point-of-care ketone meters, the task force advises having a handheld ketone meter available in the clinic.

DKA treatment involves rehydration, correcting electrolyte abnormalities, insulin administration, and treating any underlying disease.

Pay particular attention to the phosphorus concentration in cats owing to their sensitivity to hypophosphatemia-induced hemolysis. See Figure 12.1 for DKA treatment protocols.

Insulin is used primarily to eliminate ketosis but must be given in conjunction with fluid therapy and other supportive treatments. Fluid therapy alone often provides significant glucose, electrolyte, and acid-base correction in the absence of insulin, but insulin must be started within 4–6 hr of hospital admission, in most cases.

FIGURE 12.1: Diabetic Ketoacidosis Protocol for Cats

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DKA and EDKA: Treatment for Severely Compromised Patients

Refer to a 24 hr facility

DKA: Primary Care Treatment for Less Critical Patients

Consider referral if your clinic’s capabilities do not allow for optimum nursing care and hospitalization. Start supportive care if transfer to referral center is not immediately available.

• Start IV fluids to correct dehydration over 6–12 hr (12–24 hr for patients prone to fluid overload) and meet maintenance fluid requirements. Balanced crystalloids (e.g., lactated Ringer’s solution, Plasmalyte, or Normosol R) are ideal.
• Address electrolyte disturbances. Add potassium chloride (KCl) and/or potassium phosphate (KPhos) to fluids.* Address hypokalemia as a priority and consider that most DKA patients have a total body potassium deficiency. Potassium levels should ideally be >3.0-3.5 mEq/L before starting insulin. Initially monitor electrolytes every 4-6 hours, especially if high KCl or KPhos infusion rates are required.
• Use a PBGM to monitor BG. Can consider placing a CGM and then initially confirming accuracy as compared with a PBGM. If the CGM appears inaccurate, a PBGM should ideally be used to guide treatment adjustments.
• A regular insulin protocol can be initiated starting at 0.1 U/kg IM then repeated every 1–2 hr with dose adjustments made based on the serial BG monitoring.
• A glargine U-100 protocol can be used as an alternative to regular insulin.^a
  • Administer 1 U glargine U-100 IV and monitor glucose trends hourly via PBGM or CGM.
  • Administer additional 0.5–1 U glargine U-100 IM every 2–3 hr until BG is 150–250 mg/dL, and then give subcutaneous (SQ) glargine U-100 at 1–2 U every 12 hr.
• For either insulin protocol, add dextrose to fluids (2.5-5%) to maintain BG between 150-250mg/dL.^b
• Nursing care! Warmth, food, and love.^c
• Give antibiotics as needed for concurrent bacterial cystitis or other infection.
• Hospitalize until the patient is stable, rehydrated, and eating well.
• Monitor BHB every 12–24 hr until the patient is stable.
• Transition to long-term diabetic management when the patient is stable, rehydrated, and eating well.

EDKA: Primary Care Treatment for Less Critical Patients

Consider referral if your clinic’s capabilities do not allow for optimum nursing care and hospitalization. Start supportive care if transfer to referral center is not immediately available

• Discontinue SGLT2 inhibitor.
  • Be aware that the BG-lowering effect of the SGLT2 inhibitor can persist for prolonged periods (multiple days) in cats with comorbid disease, such as hepatic dysfunction or lipidosis.
• Start IV fluids with at least 5% dextrose added at an appropriate rate to correct dehydration. Balanced crystalloids (e.g., lactated Ringer’s solution, Plasmalyte, or Normosol R) are ideal.
  • If hypoglycemic (BG <150 mg/dL) at presentation, a 0.25- to 0.5-mL/kg bolus of 50% dextrose diluted 1:4 with 0.9% saline can be given intravenously.
• Add KCl or KPhos as needed to fluids and initially monitor electrolytes at least every 4-6 hours.*
• Use a PBGM or CGM to monitor glucose.
• Initiate insulin therapy within 4 hr once the BG is consistently >150 mg/dL on dextrose supplementation and potassium is >3.0 mEq/L. (See regular insulin or glargine U-100 protocols described above under DKA treatment). If the initial dextrose support is inadequate to increase BG to 150 mg/dL within 4 hr, increase the dextrose concentration to 7.5% or higher.
• Give 0.25–0.3 g of dextrose/kg/hr for every 0.1 U/kg/hr of insulin. Insulin MUST be given continuously IV or repeatedly IM, and it may be necessary to increase dextrose to more than 5% to allow for this.
• Nursing care! Warmth, food, and love.^c
• Give antibiotics as needed for concurrent bacterial cystitis or other infection.
• Hospitalize until the patient is stable, rehydrated, and eating well.
• Monitor BHB every 8–12 hr until the patient is stable.
• Transition to long-acting insulin for diabetic management; do not restart an SGLT2 inhibitor.

BG, blood glucose; BHB, beta-hydroxybutyrate; CGM, continuous glucose monitor; DKA, diabetic ketoacidosis; EDKA, euglycemic
diabetic ketoacidosis; IV, intravenous; KCl, potassium chloride; KPhos, potassium phosphate; PBGM, portable blood glucose monitor

a. Zeugswetter FK, Luckschander-Zeller N, Karlovits S, et al. Glargine versus regular insulin protocol in feline diabetic ketoacidosis. J Vet Emerg Crit Care 2021;31:459–68.

b. Gallagher BR, Mahony OM, Rozanski EA, Buob S, Freeman LM. A pilot study comparing a protocol using intermittent administration of glargine and regular insulin to a continuous rate infusion of regular insulin in cats with naturally occurring diabetic ketoacidosis. J Vet Emerg Crit Care (San Antonio). 2015;25(2):234-239.

c. Carney HC, Little S, Brownlee-Tomasso D, et al. AAFP and ISFM Feline-Friendly Nursing Care Guidelines. J Feline Med Surg 2012;14(5):337–49.

*See the AAHA Fluid Therapy Guidelines at aaha.org/fluid-therapy for instructions on supplementing fluids.

In cats that develop EDKA while being treated with SGLT2 inhibitors, BG often remains below 250 mg/dL despite ketoacidosis. The BG-lowering effect of an SGLT2 inhibitor may persist for days following discontinuation in cats with significant hepatic disease, such as hepatic lipidosis.^3,4 Despite their euglycemia, these cats require insulin administration to inhibit ketone production, resolve DKA, and help normalize metabolism.

DKA and EDKA treatments are nearly identical, except EDKA patients need immediate dextrose administration until the BG is >150 mg/dL in order to safely start insulin.

The severity of illness varies in cats with ketoacidosis. Patients typically present with nonspecific signs such as lethargy, dehydration, weakness, hyporexia, vomiting, and weight loss. They may have a history of recent PU/PD/PP.⁵ Patients who present with severe compromise require referral for 24 hr critical care, but some patients with less severe clinical signs can be treated by the primary care veterinarian. Although regular insulin administration (given IV, by continuous rate infusion, or intramuscularly [IM]) has been the mainstay of care for cats with DKA for decades, some cats can be successfully managed with various glargine protocols (see Figure 12.1).^6,7

How to Formulate Dextrose-Containing Fluids^a

*Remove an equivalent volume of the isotonic crystalloid fluid from the bag before adding 50% dextrose solution.

a. Modified from Table 14, AAHA Fluid Therapy Guidelines is available for download here.

The 2026 AAHA Diabetes Management Guidelines for Cats are generously supported by Adapet Medical, Boehringer Ingelheim, Dechra, and Merck Animal Health.