How can a diabetic patient who is in unconsciousness be taking care of and survive?

Essentially, a quick-acting carbohydrate needs to be given, followed by longer-acting carbohydrate.

Initially

Glucose- g is given by mouth, either in liquid form or as granulated sugar (two teaspoons) or sugar lumps.

GlucoGel® - formerly known as Hypostop® Gel - may be used.

Repeat capillary blood glucose after- minutes; if the patient is still hypoglycaemic then the above can be repeated (probably up to1-3 times).[2] 

If hypoglycaemia causes unconsciousness, or the patient is unco-operative

- ml% glucose or- ml of% glucose (the volume will be determined by the clinical scenario).[2] 

ml of% glucose concentration is viscous, making it more irritant and more difficult to administer, and is rarely used now.

Once the patient regains consciousness, oral glucose should be administered, as above.

If the patient is at home, or intravenous (IV) access cannot be rapidly established

Glucagon1 mg should be given by intramuscular (IM), or subcutaneous (SC) injection.[5]

This dose is used in insulin-induced hypoglycaemia (by SC, IM, or IV injection), in adults and in children over8 years (or body weight over kg). NB:1 unit of glucagon =1 mg of glucagon.

Though I am not a doctor, I am having read about some precautions to be taken by a diabetic patient as one of my family members got this disorder.

When diabetic patient is un-concious be provided with glucose water.. Laydown the body on flat  level surface keeping the head elevated by providing a pillow/something similar to hospital bed. Open the mouth and now pour glucose water. Simultaneously start saline IP liquid administration into veins. 

Within a few minutes the body gets required energy to become conciousness , but let the patient be allowed to take rest for at least  4 to6 hours on the bed to take up his basic needs.