Management of plasma biochemical changes plays an important role in determining the prognosis of patients with hyperglycemic emergencies. This biochemical aspect, which has not been examined in detail in Nigerians with hyperglycemic emergency was the focus of this study.Patients who presented with hyperglycemic emergency over a one-year period were studied. Demographic data and clinical evaluation findings were documented in a protocol. Plasma levels of glucose, electrolytes, and urea as well as urine samples for glucose, ketones, and protein were determined before and after initiating treatment for hyperglycemic emergency.Thirteen (40.6%) patients presented with diabetic ketoacidosis (DKA), 11 (34.4%) with hyperglycemic hyperosmolar state (HHS), while 8 (25%) had normo-osmolar nonketotic hyperglycemic state (NNHS). The mean glucose level at presentation in HHS was statistically significantly higher than in DKA and NNHS. Seventeen (53.1%) patients had hyperosmolality and 11 (64.7%) of these were in the HHS group, while 6 (35.3%) were in the DKA category. Mean anion gap in DKA was significantly higher when compared to patients with NNHS. Plasma bicarbonate was significantly lower in DKA than in HHS and NNHS.Presenting plasma glucose in Nigerian patients with hyperglycemic emergency appear to be generally lower than values reported elsewhere. A group of patients with hyperglycemic emergency have biochemical features intermediate between DKA and HHS; this NNHS accounts for approximately 25% of all our hyperglycemic emergency patients.