> The MSG triples the amount of insulin the pancreas creates, causing rats 
> (and perhaps humans) to become obese. They even have a name for the fat 
> rodents they create: 'MSG-Treated Rats.'

Frighteningly, there are such animals and thy do become diabetic:

http://ep.physoc.org/cgi/content/abstract/expphysiol.2007.039222v1

"Abstract
1. Rats that had been injected with monosodium glutamate (MSG) neonatally were studied for up to 70 weeks and compared with age-matched controls to study changes in glucose tolerance and sympathetic and sensory nerves. 2. At 61 and 65 weeks of age, there were significant differences in glucose tolerance between the MSG and control groups, and raised fasting blood glucose. These were not associated with changes in the number of -cells in the islets of Langerhans. In addition, the diabetic MSG-treated rats had central obesity and cataracts. 3. Hypoalgesia to thermal stimuli was present in MSG rats as early as 6 weeks and still persisted at 70 weeks. However, no differences were observed in the distribution of Substance P, the NK-1 receptor or CGRP in the dorsal horn of L3-L5 at this age. 4. Diabetic MSG-treated animals at 65 and 70 weeks of age had noradrenaline concentrations that fell significantly in the heart, tail artery, and ileum , while those in the adrenal gland and corpus cavernosum increased significantly. There was also a significant increase in adrenal adrenaline, dopamine and serotonin, largely attributable to changes of weight of the adrenal gland in the MSG animals. 5. The results indicate that MSG-treated animals develop a form of Type II diabetes by about 60 weeks of age, and that there are significant changes in amine levels in various tissues associated with these developments. "