Since impaired glucose tolerance (IGT) is a major risk factor for 
non-insulin-dependent diabetes mellitus (NIDDM), some kinds of intervention 
aiming to prevent or to delay the onset of NIDDM in subjects with IGT might be 
considered. Besides life style modification, drug therapy which could correct 
insulin deficiency and insulin resistance, might prevent progression to NIDDM. 
One agent is an alpha-glucosidase inhibitor, which delays the absorption of 
glucose from the intestine. The resulting decrease in postprandial hyperglycemia 
and hyperinsulinemia could theoretically decrease insulin resistance in IGT 
subjects and, it is hoped, prevent or delay progression to NIDDM. Metformin, an 
antihyperglycemic drug of the biguanide class, may be effective in subjects with 
IGT by reducing hepatic glucose output, enhancing insulin sensitivity, or 
through other mechanisms such as weight loss. New insulin sensitizers, such as 
troglitazone and pioglitazone, improve insulin-mediated glucose disposal by 
enhancing tissue sensitivity to the actions of insulin and reversing the insulin 
resistance, characteristic of NIDDM. Sulfonylureas might be another candidates 
of drug intervention to IGT whose insulin secretory abilities are markedly 
reduced. As far as the question, "Can NIDDM be prevented or delayed?" is 
concerned, a prospective study using life style modification or above-mentioned 
drugs, should be performed on long-term basis.