Introduction: Hydropneumothorax and Hyperosmolar Hyperglycaemic State (HHS) are uncommon disorders with serious mortality. Both conditions need appropriate intervention and monitoring in comprehensive health facilities. Reports on the occurrence of spontaneous hydropneumothorax accompanied by HHS are still limited, due to the rarity of these two disorders.Case Presentation: A 42-year-old woman with abrupt shortness of breath started 1 day ago. No coughing or chest pain. Losing weight in last six months. There was no history of any disease and medication. Physical findings were drowsy consciousness with tachycardia and weak pulse, asymmetrical chest expansion with retraction, vesicular breath sounds diminished in the left lung following hyper resonant in percussion. The extremities were cold and dry. Skin turgor was reduced. Plain CXR revealed air and fluid in left pleural cavity. Laboratory test revealed very high blood glucose with hyperosmolarity.Discussion: Hydropneumothorax is the presence of air in the pleural space accompanied by ipsilateral effusion. The manifestations include shortness of breath, increased work of breathing, and sharp chest pain, or asymptomatic. It is unclear whether this patient's hyperglycaemia is related to the occurrence of spontaneous hydropneumothorax. HHS can be diagnosed by effective serum osmolality with glucose levels plus appropriate medical presentation. The management is based on the correction of dehydration, hyperglycaemia, hyperosmolarity, and precipitating conditions.Conclusion: Both hydropneumothorax and HHS have high mortality rates, particularly when the two conditions coexist. This case met some challenging issues that might increase the mortality.