Final answer:
Internuclear ophthalmoplegia could be the diagnosis for a diabetic patient with weakness only on abduction of the left eye, leading to double vision or diplopia. This condition is diagnosed by eye movement tracking and requires further medical investigation to determine the underlying cause.
Step-by-step explanation:
If a diabetic patient presents with weakness only on abduction of the left eye, the diagnosis could be internuclear ophthalmoplegia (INO). This condition is characterized by the failure of one eye to abduct, while the other eye adducts normally during horizontal movement. Patients with INO often experience diplopia, or double vision, as the eyes are not properly aligned and point at different stimuli.
This condition can be checked by having the patient follow the tip of a pen with their eyes without moving their head. Proper diagnosis and management by a medical professional are essential, and often scanning techniques like MRI may be employed to pinpoint the cause. Internuclear ophthalmoplegia is often associated with demyelinating diseases such as multiple sclerosis but can also be related to other causes such as stroke, infection, or trauma.