"People can get diabetes at any age. Type 1, type 2, and gestational diabetes are the three main kinds. Type 1 diabetes, formerly called juvenile diabetes or insulin-dependent diabetes, is usually first diagnosed in children, teenagers, or young adults. With this form of diabetes, the beta cells of the pancreas no longer make insulin because the body's immune system has attacked and destroyed them. Treatment for type 1 diabetes includes taking insulin and possibly another injectable medicine, making wise food choices, being physically active, taking aspirin daily-for some-and controlling blood pressure and cholesterol.
Type 2 diabetes, formerly called adult-onset diabetes or noninsulin-dependent diabetes, is the most common form of diabetes. People can develop type 2 diabetes at any age-even during childhood. This form of diabetes usually begins with insulin resistance, a condition in which fat, muscle, and liver cells do not use insulin properly. At first, the pancreas keeps up with the added demand by producing more insulin. In time, however, it loses the ability to secrete enough insulin in response to meals. Being overweight and inactive increases the chances of developing type 2 diabetes. Treatment includes using diabetes medicines, making wise food choices, being physically active, taking aspirin daily-for some-and controlling blood pressure and cholesterol."
Quote from: Your Guide to Diabetes: Type 1 and Type 2 - National Diabetes Information Clearinghouse
Sooooo...I think of Type 1 as "DOA" - the poor little pancreatic cells are dead on arrival. Kaput. Nada. They never had a chance to make insulin, poor souls. Never have made insulin, never will. This is why Type 1 folks need continuous insulin (some people call this "insulin dependent"), or they will die. Oral diabetes meds won't do the trick for these folks because none of them will produce insulin magically.
I think of Type 2 as Scotty from Star Trek ("I'm givin' her all she's got, Captain!!") In Type 2, the body can and does produce insulin. It's just that it doesn't do the job, because the cells aren't utilizing it properly (sometimes people say the cells are "insulin-resistant"). Initially, the body will try to keep up by producing more insulin ("I need more dilithium crystals!") but that won't last forever. Now, these people may or may not need insulin (some people call this type "non-insulin dependent"). Some Type 2 folks are diet controlled; some controlled with oral meds; some require insulin. Oral meds all work differently; some inhibit absorption of carbs; some stimulate the pancreas to make more insulin, some improve the body's response to insulin. It's a matter of finding what works for the patient.
You mentioned the sliding scale and Lantus. For Type 2 folks, again, this is a matter of what works for the patient. Just one scenario: when a Type 2 patient is not controlled with diet/oral meds alone, a doctor may start a patient on Lantus at night. This is long-acting and sloooooooooow, so it works overnight to maintain blood sugars, and you don't have to worry so much about bottoming a patient out. If the patient still has outrageous blood sugars, or varies greatly with meals, they may order "coverage." This is a bump of short acting insulin to "cover" the extra glucose ingested at mealtime. This might be something like Novolog, which is rapid-acting. (70/30 insulin is a mix of shorter acting and longer acting...again, it's all about what controls the blood sugar best for the patient with a minimum of highs and lows.)
Hope this helps