The relationship between fast food and diabetes is largely correlative rather than causative. Moreover, any relationship between fast food and diabetes is dependent on consumption of unhealthy foods in excess. It is not reasonable to say that a person who occasionally eats fast food or who eats fast food that is relatively healthy is at an increased danger of developing type 2 diabetes. That said, the relationship between particular eating habits concerning extremely unhealthy fast food and diabetes is clearly one of causation. If a person becomes extremely unhealthy or obese from lack of activity and an unhealthy diet, he or she is at a dramatically increased risk of developing type 2 diabetes.
It is easiest to think of the relationship between fast food and diabetes as a two-step process. First, a person eats an excessive amount of unhealthy food over a long period of time, thereby becoming obese. Then, being obese causes health problems such as diabetes. The problem with linking a particular food service with obesity is that many people manage to eat food from those institutions in moderation. Diabetes is not associated with all consumers of fast food, but merely those who fit in a particular group that, whether due to income, will power, or upbringing, eat a fully unreasonable amount of fast food.
Fast food is not related to all types of diabetes. Type 1 diabetes often appears in childhood and can be seen in individuals of all eating habits. Only type 2 diabetes has any relation to fast food.
Whether or not fast food and diabetes are related causally, there is certainly overlap between the kinds of people who eat fast food excessively and the kinds of people who develop diabetes. This may be the fault of the quality of the fast food, the size of the portions, or even the ease with which a person can get fast food. On the other hand, it could be compounded by the other foods that people who eat a lot of fast food eat and the lack of activities they pursue. Making lifestyle choices that end in serious health problems like diabetes is a social epidemic in many areas.
There is also a relationship between fast food and diabetes for people who already have the disorder. People with diabetes must avoid many of the foods available at fast food restaurants. This can be inconvenient for people who work or simply enjoy fast food. One way to overcome this problem is to read the nutrition facts available at fast food restaurants or research them online before making a food selection. By avoiding fast food that is highly unhealthy, one can often still take advantage of the convenience of fast food without any of the health risks.