Diabetic coma is loss of consciousness occurring as a result of very high blood sugar. Its causes are similar in both type 1 and type 2 diabetes, but with the important difference that other abnormalities of the blood chemistry may contribute to the coma in type 1 diabetes. These other abnormalities occur as a result of the almost total lack of insulin that is present in type 1 diabetes. For this reason, while blood sugar is almost always very high in people with type 2 diabetes who are in diabetic coma, being several hundreds (of mg/dl) to 2000 or more, it can be less elevated in people with type 1 diabetes, sometimes as low as only 200 or 300.
In the case of type 1 diabetes, diabetic coma can occur solely as a result of having insufficient insulin in the body (e.g., running out of or not taking one’s insulin), while in the case of type 2 diabetes, there is almost always another stress to the body that precipitates the coma, such as infection, dehydration, etc. If the serious abnormalities of blood chemistry that led to diabetic coma are not corrected rapidly, death can occur. Although the derangements in blood chemistry are more complex and severe in type 1 diabetes than in type 2 diabetes, there is a higher mortality in type 2 diabetic coma because people suffering from it tend to be older, in less robust health, and with more cardiac risk factors.
Also, additional symptoms of nausea, vomiting, and abdominal pain occur in the derangements of type 1 diabetes leading to coma and the diagnosis may be made earlier as a result. In the early stages of coma in type 2 diabetes, abnormalities of brain function and conscious-ness are more prominent due to the extreme degree of dehydration. Moreover, the illness that precipitated the coma may carry its own serious health risks. Although only a minority of patients with diabetes will succumb to coma, it remains an important medical emergency that requires immediate intervention.