Objective To investigate the magnetic resonance imaging (MRI) features and classification of brainstem stroke with hyperglycemia in relation to the clinical outcome and the onset of brainstem stroke, and identify the risk factors and explore the pathogenesis of brainstem stroke. Methods This case-control study involved 218 hyperglycemic patients with acute cerebral stroke and 218 stroke patients with normal blood glucose (control group). The mRS scores of the patients were used to compare the clinical outcomes of the patients with different types ofbrainstem infarct. Results The risk factors and MRI features of the two groups were compared, and according to the MRI features,brainstem stroke was classified into 5 types, namely the midbrain infarct, pontine infarct, medullary infarct, entire brainstem infarct, and brainstem lacunar infarct. For midbrain, pontine, and medullary infracts, 3, 5 and 3 subtypes were identified, respectively. The incidence of brainstem stroke was significantly higher in hyperglycemic patients (P<0.05). Hyperglycemic stroke patients had significantly higher incidence of hypertension and higher systolic blood pressure (SBP), fibrin (Fib), triglyceride (TG),cholesterin (TCHO), and low-density lipoprotein (LDL-C) levels than normoglycemic patients (P<0.05), but the diastolic blood pressure (DBP) and high-density lipoprotein (HDL) showed no significant differences between them (P>0.05). No significant differences were found in TG, Fib, TCHO, HDL-C,LDL-C, number of patients with hypertension, time course of hypertension, SBP or DBP between hyperglycemic and normoglycemic patients (P>0.05). In hyperglycemic patients, the level of FBG, postprandial blood sugar, glycosylated hemoglobin and other risk factors were comparable between the patients with brainstem infarct and those with infarct in other locations (P>0.05). More than half (50.4%)of the patients with brainstem infarction had mRS scores of 2-5, and the rest (49.6%) had scores of 0-1.Conclusion Hyperglycemia is closely associated with brainstem infarction and more likely to compromise the perforating branches of blood vessels in the posterior circulation to cause brainstem stroke. Brain stem infarction causes higher rates of mortality and disability.