Euglycemic Diabetic Ketoacidosis in Adult-Onset Autoimmune Diabetes

A case study has shed light on an unusual presentation of autoimmune diabetes in a previously healthy 34-year-old man. This patient experienced euglycemic diabetic ketoacidosis as the initial indication of his condition, which is often mistaken for type 2 diabetes, especially since his blood sugar levels were below conventional diagnostic thresholds.

Understanding the Condition

Adult-onset autoimmune diabetes can manifest in various ways, and in this instance, the man exhibited symptoms typically associated with diabetes. Notably, he did not initially have high blood sugar, but rather had symptoms that included fatigue, nausea, a reduced appetite, increased thirst, and mild difficulty in breathing. Despite no prior diabetes diagnosis or symptoms, he spent three days experiencing these progressive symptoms.

Initial Diagnosis and Findings

The patient had a notably low caloric intake prior to his hospital visit, consuming only around 700 kilocalories daily. Upon examination, his weight indicated a body mass index of 21.4 kg/m², supporting his classification as a lean individual.

Diagnostic tests revealed severe metabolic acidosis and significant ketone production, with an arterial blood pH recorded at 7.23 and a bicarbonate level of just 13 mmol/L. Interestingly, his blood glucose level was recorded at 198 mg/dL, indicating euglycemia despite the presence of ketoacidosis.

Autoimmunity Confirmed

Further tests indicated an autoimmune process at play. The patient's hemoglobin A1c was documented at 7.1%, paired with low fasting C-peptide levels suggested an impairment in insulin production. Essential autoantibodies were identified, including those targeting GAD65, IA-2, and ZnT8 islet markers.

Efforts to evaluate other potential causes for the metabolic acidosis were conducted, ruling out infectious, toxic, renal, and adrenal issues. The significant ketoacidosis observed could not be solely attributed to his limited caloric intake.

Treatment and Follow-Up

Management of the acute episode included intravenous fluids, insulin infusion supplemented with glucose, and potassium replacement. Remarkably, the patient saw improvement within 24 hours and was subsequently stabilized for discharge with a basal-bolus insulin regimen.

Three months post-discharge, during an outpatient follow-up, the patient had not experienced any further episodes of ketoacidosis, although his C-peptide levels remained low. The findings in this case emphasize the importance of molecular diagnostic testing for autoimmune diabetes, especially in adults presenting with atypical symptoms.

It is crucial for healthcare providers to consider underlying autoimmune diabetes, even when patients present with euglycemic diabetic ketoacidosis.

Implications for Practice

This case highlights the critical need for careful evaluation in instances of unexplained high anion gap acidosis, particularly when blood glucose readings are deceptively low. Clinicians must ensure appropriate ketone level testing is part of the diagnostic process. Additionally, prolonged follow-up is essential to differentiate between latent autoimmune diabetes in adults and adult-onset type 1 diabetes effectively.