Consider, if you will, a nightclub district. Every club is like a cell in the body, with the street outside being the bloodstream. At the door to every club is a bouncer, whose job is to keep out the riff-raff and limit the number of "average" people who get in. The bouncers (who are a bit more simple-minded than real world bouncers) will always let in the pretty people, the rich people and the famous people, but those people do need a certain leavening of schlubs to look prettier, richer or more famous than. And, of course, a mostly empty club is a boring club. Left to their own devices, the bouncers will only let in average people very rarely, and usually only when the street is absolutely flooded with them. They also occasionally let in the wrong sort, especially when bribed.

    The bouncers are the cell membranes, engaging in selective permeability. And those average people? They're glucose. The club needs some of them, but the bouncer doesn't want to let in too many. If the chamber of commerce uses advertising to drive more people to the club district, that's like eating more. Viruses and other pathogens are the scum that bribe or trick their way past the bouncers.

    Got it so far? Good. Now, in this hypothetical nightclub district, the club owners have collectively hired a bunch of guys whose job it is to mingle, gauge the mood of the room, and occasionally tell the bouncer to let in a few more average folks to keep the party from dying out. These guys are insulin. As long as they're on the job, the party will never end so long as there's anyone even remotely acceptable on the street wanting to get in. And they're also pretty good at recognizing if the street's getting too crowded, and letting in a few pity cases just to make people think they stand a chance.

    In Type 1 Diabetes, the club owners have, for some brilliant managerial pointy-headed reason, started to fire the guys who advise the bouncers. There's fewer and fewer of these facilitators keeping an eye on the same number of clubs, and some clubs end up going dead for long stretches because the bouncer's not letting enough people in. In other words, the body's started killing off its own insulin producers. The usual solution is for the chamber of commerce to hire replacements from their own budget to keep doing the job...injected insulin. They may even set up an office in the nightclub district to manage this process, taking it entirely out of the hands of the club owners (i.e. an implantable insulin pump).

    In Type 2 Diabetes, the facilitators are still out there, but they're just not doing as good of a job. Maybe the number of clubs has gone up without an increase in the facilitator staffing (you're getting fatter and your body can't keep up with insulin production). Maybe the chamber of commerce's ad campaign is too successful, the streets are always flooded with tourists, and the facilitators are being run ragged (you're eating too much). Maybe the guys are just getting burned out on the job and absenteeism is running rampant (the pancreas isn't producing as much insulin). But usually what happens is that the bouncers stop trusting the facilitators. If asked to let in five people, they only let in three. Maybe it takes longer to convince them to let in anyone at all. Your cells are becoming insulin resistant.

    In this case, there's a lot of options. The "hire more guys" solution still works, but it can be overkill, and is best used as a stopgap while other programs are put into place.

    You can try various ways to make the bouncers less conservative, maybe a bonus for every night the club is packed. You can hire pretty people to go around, grabbing average people and saying "They're with me". You can hire people to distract the bouncers while people sneak in. You can even take bouncers off the door in extreme cases. These methods all represent various drugs that directly lower the cell's defenses against glucose getting in, bypassing the need for insulin. (I'm not sure if any drugs do this very well, though.)

    Alternately, you can hire different facilitators. You can train the bouncers to better recognize the sorts of things the facilitators look for, so they're more likely to pay attention to the requests for admission. This sort of approach is like using drugs such as Metformin, that make cells more sensitive to the insulin you've got.

    Another option is at the club level, doing things to help keep the party going even with lower numbers of people. Getting the most out of the glucose that makes it into the cell, improving the metabolism of it. Drugs can do this, and so can exercising. When you're exercising more, sugar that makes it into the cell is more likely to get turned into better energy sources instead of hanging around for a while and then being excreted.

    Then, of course, you could always stop driving people into the nightclub district, reduce the crowds on the street, and make it easier for everyone to just do their job. You can also target your advertising to try to get more pretty people without simultaneously bringing in more non-pretty people. Eat less, eat better.

    And there you have it. A properly working body is like a well-run nightclub district. The parties never end, the clubs don't go out of business, and everyone's happy. Except the guys who still can't get past the bouncer and end up drunk in a gutter (even a healthy person excretes some sugars)....