How does the diabetes symptom polyphagia occur? Something that stimulates our hunger center? What’s its mechanism?

I don’t think that polyphagia [increased hunger] in the sense of inappropriate excessive intake of food is a necessary part of the clinical syndrome of any form of diabetes.

Certainly though there are circumstances where this can happen temporarily. Insulin itself seems to be a potent appetite stimulant and this can be observed when insulin is started in the new onset diabetic. It can also be a cause of excessive weight gain when maintenance doses of insulin are too high. The converse of this is the practise, particularly in teen age girls of reducing their insulin dose in order to lose weight. Hypoglycemia does not seem to be a factor.

Of special interest in the last few years has been the relationship between obesity, diabetes and leptin. The latter is a protein linked to the OB gene which is generated in fat cells. Its action in both animal and man is to effect a reduction in appetite through the brain’s hypothalamus. Blood levels are stimulated by insulin. This immediately raises the puzzle as to why, if insulin increases Leptin levels which should then depress appetite, does insulin in fact seem to have reverse effect in clinical situations. This contradiction between clinical and laboratory observation has so far not been explained nor has the link between obesity and Type 2 Diabetes, although it looks as though the mechanism may be an association between leptin and insulin resistance.

DOB