Clinical Manifestations

There are five stages in the natural history of DM:

First stage: susceptibility based on a combination of

(1) genetic risk factors; (2) physiological states such as obesity for type II diabetes; (3) and environ­mental factors including diet, climate, activity, and other life-style patterns.

Second stage: glucose intolerance, which is recog­nized as a phase preceding both insulin-dependent and non-insulin-dependent diabetes. Not all indi­viduals having impaired glucose tolerance prog­ress to symptomatic diabetes.

Third stage: chronic hyperglycemia without compli­cations.

Fourth stage: frank diabetes with complications but without disability.

Fifth stage: disability due to functional impairment from the complications of diabetes, which involve primarily the vascular system. Common complica­tions include renal disease, blindness due to retinopathy, neuropathy, cerebral vascular dis­ease, cardiac disease, and peripheral vascular dis­ease often leading to lower limb amputation.