From Harvard: Sweeteners, obesity, and diabetes

http://www.ncbi.nlm.nih.gov/pubmed/22289979

Curr Diab Rep. 2012 Jan 31. [Epub ahead of print]
Sweeteners and Risk of Obesity and Type 2 Diabetes: The Role of Sugar-Sweetened Beverages.
Malik VS, Hu FB.
Source
Department of Nutrition, Harvard School of Public Health, 665 Huntington Avenue, Boston, MA, 02115, USA.

Abstract
Temporal patterns over the past three to four decades have shown a close parallel between the rise in added sugar intake and the global obesity and type 2 diabetes (T2D) epidemics. Sugar-sweetened beverages (SSBs), which include the full spectrum of soft drinks, fruit drinks, energy and vitamin water drinks, are composed of naturally derived caloric sweeteners such as sucrose, high fructose corn syrup, or fruit juice concentrates. Collectively they are the largest contributor to added sugar intake in the US diet. Over the past 10 years a number of large observational studies have found positive associations between SSB consumption and long-term weight gain and development of T2D and related metabolic conditions. Experimental studies provide insight into potential biological mechanisms and illustrate that intake of SSBs increases T2D and cardiovascular risk factors. SSBs promote weight gain by incomplete compensation of liquid calories and contribute to increased risk of T2D not only through weight gain, but also independently through glycemic effects of consuming large amounts of rapidly absorbable sugars and metabolic effects of fructose.