Catching the pre-diabetics or those with Impaired glucose tolerance early enough and giving them a regimen of diet, exercise and anti diabetic drugs, will increase their insulin sensitivity, preserve their β cells of the pancreas and delay the onset of diabetes.  Here is a study.

Team@CMHF

In the U.S., ∼ 21 × 10(6) individuals have type 2 diabetes, and twice as many have impaired glucose tolerance (IGT). Approximately 40-50% of individuals with IGT will progress to type 2 diabetes over their lifetime.

Therefore, treatment of high-risk individuals with IGT to prevent type 2 diabetes has important medical, economic, social, and human implications. Weight loss, although effective in reducing the conversion of IGT to type 2 diabetes, is difficult to achieve and maintain. In contrast, pharmacological treatment of IGT with oral antidiabetic agents that improve insulin sensitivity and preserve β-cell function uniformly have been shown to prevent progression of IGT to type 2 diabetes.

The most consistent results have been observed with the thiazolidinediones (Troglitazone in the Prevention of Diabetes [TRIPOD], Pioglitazone in the Prevention of Diabetes [PIPOD], Diabetes Reduction Assessment with Ramipril and Rosiglitazone Medication [DREAM], and Actos Now for the Prevention of Diabetes [ACT NOW]), with a 50-70% reduction in IGT conversion to diabetes. Because individuals in the upper tertile of IGT are maximally/near-maximally insulin resistant, have lost 70-80% of their β-cell function, and have an ∼ 10% incidence of diabetic retinopathy, pharmacological intervention, in combination with diet plus exercise, should be instituted.

Ref: http://www.docguide.com/type-2-diabetes-can-be-prevented-early-pharmacological-intervention?hash=80445d1a&eid=19996&alrhash=2efbb8-880279c42369cc2f8adcb48a6daaf3d2