Amylin Pharmaceutical Inc. shares fell nearly 45% after the company said a study showed its developmental diabetes drug did not significantly improve long-term metabolic functioning in type II diabetics. Shares of San Diego-based Amylin fell $6.44 to close at $8.44 in Nasdaq trading after dropping as low as $8.13. The company reported the study results late Friday after the market closed. Though the drug, known as pramlintide, lowered blood sugar levels in type II diabetics over six months, it did not show significant benefit over a 12-month period, the company said. Pramlintide is a synthetic version of human hormone amylin that is absent in insulin-using diabetics. Amylin said the lack of long-term improvement in blood sugar control may be caused by changes in the patients' insulin dosing over the course of the study. The study, co-sponsored by Johnson & Johnson, was aimed at proving that amylin replacement therapy in insulin-using diabetics can help them control their metabolism without the common side effects of insulin therapy such as weight gain and sudden dips in blood sugar.