One of the common clinical observations regarding long-standing diabetes is peripheral neuropathic pain, probably due to its destructive effects on the pain modulating neurons of the dorsal gray column of the spinal cord. Accordingly, the current study was aimed to analyze the effect of experimental hyperglycemia on pain modulating neurons in the lamina I-III of lumbar region of spinal cord of albino rats. Thirty-six albino rats with average weight ~250 g were grouped equally into six. Diabetes was induced with a single dose of streptozotocin (STZ, 60 mg/kg, i.p.). At the end of each experimental period, rats were euthanized by deep ether anesthesia, blood was collected and animals were perfused with Karnovsky fixative. Spinal cord was dissected and processed for histopathological and morphometric parameters and blood for biochemical analysis. Biochemical analysis of all diabetic groups revealed increased serum creatinine and reduced serum total protein. Histopathology and histomorphometry of dorsal gray column and ependymal cells and surrounding structures revealed that with the progressively increasing duration of hyperglycemia was associated with decreased number of pain modulating neurons in the lamina I-III as well as ependymal cell and in addition deposition of collagen fibers in the tunica adventitia of spinal arteries and around the small spinal vessels. The associations of long-standing hyperglycemia with reduction of dorsal gray column inter neurons, demyelination of nerve fibres and excessive deposition of collagen fibers in the tunica adventitia of blood vessels appear to be important contributing factors likely to be responsible for the diabetes-induced peripheral neuropathic pain