People used to think that sugar was better then normal carbohydrates because it has a lower glycemic index but a diabetes researcher out of San Francisco has proven that your mother was probably right. Those sweets are not good for you. Although its lower glycemic sugar causes 'fatty liver' which seems to lead to both heart disease and diabetes.
Again this is not a settled question. There are medical professionals who used to buy into the Mayo Clinic's point of view. But they do not anymore.
Here is some of what Doctor Lustiq says about sugar..
"We asked the question, "What in the world's food supply explains diabetes rates, country-by-country, over the last decade?" We melded databases from the Food and Agriculture Organization (FAOSTAT), which measures food availability, the International Diabetes Federation (IDF), which measures diabetes prevalence, the World Bank World Development Economic Indicators, and the World Health Organization Global Infobase. We assessed total calories; meat (protein); oils (fat); cereals (glucose); pulses, nuts, vegetables, roots, and tubers (fiber); fruit excluding wine (natural sugar); and sugar, sugarcrops, and sweeteners (added sugar). We controlled for poverty, urbanization, aging, and most important, obesity and physical activity. "
"Bottom line -- only changes in sugar availability explained changes in diabetes prevalence worldwide; nothing else mattered. "
So again you don't HAVE to believe me. I really don't care. But don't pretend that believing sugar and diabetes is linked is some crackpot theory. Both low carb and low sugar diets are gaining credence in the medical community as being responsible for these modern maladies. As I said - in agreement with others here - the principle factor is dietary changes. It's true that people might be exercising less. But call me crazy I think the average third worlder in India does a hell of a lot more physical labor then rich movie stars here - and they are heck of a lot fatter.
I could go into why - but its kinda off topic. Diet is the key..