Joslin Diabetes Center is known for being many things: it’s a Harvard Medical School affiliate, one of the world’s largest diabetes research centers and, in recent years, a money-losing institution that has been a revolving door for chief executives. But the diabetes clinic, in Boston’s Longwood Medical Area, has never been known as a hotbed of entrepreneurship. Its latest chief executive, John L. Brooks III, who took over in the spring, wants to make it just that. If he succeeds, it could boost the financial fortunes of Joslin - and, in the process, assure the independence of the 113-year-old institution, which has struggled amid declines in fundraising and cuts in research funding and insurance payments. The dramatic global increase in the prevalence of diabetes could present a market opening for Joslin if it is able to capitalize, Brooks said. “You need to put a more commercial package around an opportunity,’’ said Brooks, a former life sciences entrepreneur and venture capitalist. “As diabetes continues coming onto the map, we want to be involved in bringing innovation to the market.’’