Have a look at the website above - it helped me to understand Gene Therapy better. The website is really good in explaining the simple steps. Hope you find this useful.

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Sorry, but I couldn’t tell you what chromosome it’s on.
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my specialist

A previous answer mentioned LADA, which is a minor variant of type 1, but it is not simply "type 1 appearing in an adult". Type 1 is caused by a spectrum of antibodies ("GAD antibodies") attacking and killing the insulin-producing cells of the pancreas and it develops very quickly - I personally went from no evidence of diabetes to hospitalized with near-fatal ketoacidosis in the space of about 6 months. LADA, on the other hand, involves only a single antibody (GAD-65) attacking the pancreas and, therefore, tends to develop more slowly over the course of a year or more.

Type 1 diabetes is not strictly hereditary - as already mentioned, the chances of passing it on to your children are very low and some of us have developed it with no known family history of type 1 - but there is probably a genetic component making you susceptible, which then needs to be triggered by some environmental influence. We’re not sure yet what this environmental factor is, but it’s widely believed to be a virus.

Although I haven’t looked into the details, there have been many reports over the last week or two about a recent study suggesting that type 1 diabetes may be related to vitamin D deficiency early in life.

The major difference is that type 1 diabetes is an autoimmune disorder, in which your immune system destroys your body’s ability to produce insulin, while type 2 diabetes is a metabolic disorder in which your body fails to respond properly to insulin. Because insulin is an absolute requirement for (mammalian) life, people with type 1 diabetes must receive externally-supplied insulin (via injections or an insulin pump) or they will die in fairly short order. People with type 2, on the other hand, may require externally-supplied insulin to manage their blood glucose levels and prevent long-term complications, but will generally not be in immediate danger if it is unavailable. The primary treatments for type 2 diabetes are based in the use of exercise and medication to improve their body’s ability to respond to insulin and controlling diet to minimize the amount of insulin required in the first place.
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Type 1 diabetes, developed at age 36

The most common form of diabetes is Type 2 diabetes. It starts when the body does not correctly respond to insulin, which is a hormone that is released by the pancreas. This is a lifelong disease that is caused by high levels of sugar being present in the blood.
References :
http://diabetesmellitustreatment.com/

The cause of Diabetes is not yet known, but studies have shown certain genes to be associated with an increased risk for Diabetes.

Type 1 diabetes is characterized by a loss of 90% or more of the insulin (a hormone necessary for the uptake of glucose from blood) producing cells of the pancreas so that very little, if any, insulin is present in the body. In Type 2 Diabetes, on the other hand, insulin is present often in normal or even greater than normal levels. The issue for those with Type 2 diabetes is insulin resistance. This resistance means that the insulin present is not very effective, thus more of it is needed, and the body is unable to meet that increased demand for the hormone (insulin).
References :
I’m a Diabetic
Medical School

http://www.merck.com/mmhe/sec13/ch165/ch165a.html
http://www.diabetes.org/diabetes-basics/type-1/
http://www.jdrf.org/index.cfm?page_id=103442#hereditary

treatment:
-type 1s need insulin, although it can be injected or with a pump
-type 2s vary. Ranges from diet and exercise alone (fairly rare) to various meds to insulin.

lifestyle changes:
-for both, diet is really important.
-type 1s have to pay really close attention to diet since how much insulin is given depends upon food intake. On the other hand, type 1s can adjust insulin depending upon food so it’s easier to "cheat" by just giving extra insulin. Requires a lot of planning–testing blood sugar frequently, snacking depending upon when insulin was given, blood sugars, etc. Exercise is important, but has to be planned for to avoid/minimize low blood sugars.
-type 2s: since most are overweight, diet and exercise are very important. Weight loss should be a goal and can even help to slow down the disease process.

Check on the American Diabetes Association website for more information.
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Treatment: Type 1 - insulin + lifestyle changes + dietary strategy changes
Type 2 : first line of treatment lifestyle changes and dietary strategy changes
if the first line fails, need to go for oral blood sugar lowering drugs (Metformin, Glibenclamidum, etc.)
if the above steps fails, then it is a must to start insulin therapy.

Lifestyle changes: avoid sugar foods (those high in simple sugar which raise quickly blood sugar)
use more complex sugar foods (life fibers found in whole grain foods)
Keep exercised (at least 30 minutes per day) to control blood sugar and weight
Avoid smoking, drinking alcohol, because they raise blood sugar apart causing many other diseases and fatalities.
Try to cope with stress: this helps ameliorate your blood glucose metabolism
use more fruits and vegetables (high in fiber, less in sugar and tasty too)
drink plenty of water to help your body metabolism

More details find at http://www.all-about-beating-diabetes.com/causes-of-diabetes-info.html
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The aim of http://www.all-about-beating-diabetes.com is to bring latest news on beating diabetes naturally.