Data from 191 post-mortem cases where post-mortem blood beta-hydroxybutyrate (βHB) and acetone concentrations and vitreous humor glucose concentrations (where available) had been measured were retrospectively investigated to determine the markers required to identify and distinguish between Alcoholic Ketoacidosis (AKA), Diabetic Ketoacidosis (DKA) and Hyperosmolar Hyperglycemic State (HHS). Blood βHB concentrations above 250 μg/mL were considered significant and it was shown to be the preferred marker of ketoacidosis. All cases with significant βHB detected also had acetone present (greater than 2mg/dL) demonstrating that acetone can be used as a marker to identify ketoacidosis and can be used to indicate when βHB measurement is necessary. Vitreous humor glucose concentrations above 6.9 mmol/L were considered high and indicative of hyperglycemia prior to death. Vitreous humor glucose concentrations can be used to distinguish between DKA and ketoacidosis from other causes and to identify deaths due to HHS. The data showed that ketoacidosis can occur without a history of alcoholism or diabetes. Many diabetics are undiagnosed for many years. Therefore, DKA or HHS should be considered in sudden or unexplained deaths and glucose should be routinely measured especially in cases with risk factors for diabetes including obesity, old age, a history of mental health problems or treatment with atypical antipsychotic drugs including clozapine, olanzapine, quetiapine and risperidone.