It turn out that not all sugar is bad. Put another way, not everything in sugar is bad for diabetics. Sugar (sucrose) consists of one glucose and one fructose molecule, or 50% glucose and 50% fructose. The body does different things with glucose vs fructose.
There are several studies which tease out the differences between glucose and fructose. Here’s one of the studies (Kimber L. Stanhope, et.al. Consuming fructose-sweetened, not glucose-sweetened, beverages increases visceral adiposity and lipids and decreases insulin sensitivity in overweight/obese humans. The Journal of Clinical Investigation, 2009;5:119, pp 1322-1334). The study:
To assess the relative effects of these dietary sugars during sustained consumption in humans, overweight and obese subjects consumed glucose- or fructose-sweetened beverages providing 25% of energy requirements for 10 weeks.
Switching out between the two sugars sounds like a fairly easy test and should have resulted in identical results. And the results were the same for weight gain so both parts of sugar can make you fatter.
There was a very important difference, though, where the fat was located. In the group eating fructose the visceral adipose volume was significantly increased only in subjects consuming fructose.
Fasting plasma triglyceride concentrations increased by approximately 10% during 10 weeks of glucose consumption but not after fructose consumption.
In contrast, hepatic de novo lipogenesis (DNL) and the 23-hour postprandial triglyceride AUC were increased specifically during fructose consumption. Similarly, markers of altered lipid metabolism and lipoprotein remodeling, including fasting apoB, LDL, small dense LDL, oxidized LDL, and postprandial concentrations of remnant-like particle–triglyceride and –cholesterol significantly increased during fructose but not glucose consumption.
In addition, fasting plasma glucose and insulin levels increased and insulin sensitivity decreased in subjects consuming fructose but not in those consuming glucose.
These data suggest that dietary fructose specifically increases DNL, promotes dyslipidemia, decreases insulin sensitivity, and increases visceral adiposity in overweight/obese adults.
Interesting results. For a newer paper which summarized other studies on the subject see this (Stanhope KL, Schwarz J-M, Havel PJ. Adverse metabolic effects of dietary fructose: Results from recent epidemiological, clinical, and mechanistic studies. Current Opinion in Lipidology. 2013;24(3):198-206.)