How long can a diabetic coma last?

Varies: Though most wake up significantly within a few hours of getting Insulin (or glucose if hypoglycemic), there can be permanent brain damage if the brain is starved of glucose (from either lack of Insulin to utilize the glucose or hypoglycemia) long enough, .

Variable duration: The duration of diabetic coma is related to correction of the metabolic abnormalities leading to coma. It may be short if treatment is instituted shortly after coma begins. The longer the coma remains untreated, the greater the likelihood of permanent neurologic damage or even death.

Varies: There are many variables to affect the coma. It depends on the degree of the coma and what complications have occurred as a result. Sadly, some patients do not recover.