1. Causes of type 2 diabetes: The main mechanisms of type 2 diabetes include insulin resistance and relative insulin deficiency. Unhealthy diets with excessive consumption of low-quality carbohydrates, such as rice and flour-based foods, and insufficient intake of high-quality carbohydrates like whole grains and vegetables, can lead to insulin resistance. Additionally, a preference for high-salt, high-fat, high-sugar, and spicy foods can damage pancreatic cells.

2. Snacks that can "destroy" your pancreas: 
a. Nuts: Excessive consumption of high-calorie and high-fat nut snacks like peanuts, melon seeds, and walnuts indirectly increases blood sugar levels and impairs pancreatic function. 

b. Carbonated drinks: Regular consumption of carbonated beverages, even those labeled as sugar-free, can still contain hidden sugars that can lead to insulin resistance and type 2 diabetes. 
c. Spicy snacks: Snacks like spicy noodles and fish fillets may contain hidden sugars, which contribute to insulin resistance. 
d. Deep-fried snacks: Popular fried foods like scallion pancakes, fried dough sticks, and twisted doughnuts are high in fat and can lead to weight gain, indirectly impairing pancreatic function and contributing to insulin resistance.

3. Friendly foods for your pancreas: 
a. Whole grains: Foods like oats, quinoa, and whole wheat bread are rich in dietary fiber, can increase satiety, reduce main carbohydrate intake, and promote insulin secretion or enhance insulin sensitivity. 

b. Bitter melon: Bitter melon is a common food for controlling blood sugar levels and is high in dietary fiber, making it popular among diabetes patients. 
c. Cucumber: Cucumbers have low sugar content and a low glycemic index, making them a good substitute for some main carbohydrates. 
d. Black fungus: Black fungus contains polysaccharides that can reduce total cholesterol, triglycerides, and low-density lipoprotein cholesterol.

It also protects pancreatic cells from damage. 
e. Grapefruit: The compound called naringin in grapefruit can increase insulin sensitivity. It functions similarly to lipid-lowering drugs and glucose-lowering drugs, making it suitable for people with abnormal blood sugar levels. However, individuals taking statins should avoid consuming grapefruit due to potential interactions.

In conclusion, adopting a healthy diet, maintaining a normal weight, and adopting regular lifestyle habits are important for preventing type 2 diabetes. Additionally, incorporating friendly foods into your diet, such as whole grains, bitter melon, cucumber, black fungus, and grapefruit, can support pancreatic health.