Chugging more than one sugar-sweetened soft drink a day appears to significantly increase a woman's chances of developing diabetes, says a Harvard study that found the extra sugar does more than just add pounds. Women in the study who drank at least one sugar-sweetened soda a day were 85 percent more likely to develop type 2 diabetes than those who drank less, said Matthias B. Schulze, who presented the Harvard School of Public Health research at the American Diabetes Association's 64th scientific sessions.