The hypothesis is, in subjects with persistent impaired glucose tolerance(IGT) , sitagliptin will decrease the conversion rate to diabetes as compared to a placebo in three years.

The DPP-4 inhibitor Sitagliptin may be a suitable preventive agent in subjects with IGT or IFG on account of observed functional improvements in islet cell function and potential protective effect on beta cell mass.

Objectives of the study

1. Primary objectives :

   - To test whether the DPP4 inhibitor Sitagliptin is effective in preventing conversion of IGT to diabetes when compared with a placebo.

2. Secondary objectives:

   • To assess rates of reversal from IGT to Normal Glucose Tolerance (NGT) in IGT patients administered Sitagliptin
   • To assess the effect of Sitagliptin on measure of beta cell function and insulin resistance in patients with IGT.

Study design

Double blind placebo controlled, parallel group study - three years follow up .

Subjects with IGT in the age group of 30-55 years (n=900) will be identified by screening with a standard OGTT. Selected subjects will be randomized to the control arm using placebo and the two study arms using Sitagliptin. At baseline all group will receive a standard advice on lifestyle modification. The dose of sitagliptin will be 100 mg/d. The subjects will be reviewed at 6 monthly intervals and repeat OGTT will be done annually.

Proforma containing details of anthropometry, occupation, physical activity, diet habits, details of medications, regularity of treatment and biochemical investigations will be filled up at each interview.

Investigations:

Initial Screening

1. Demographic data
2. Height, weight, waist and hip measurements.
3. Details of family history of diabetes, hypertension and cardiovascular diseases.
4. History of any other major illness.
5. History of blood pressure and measurements.
6. Details of education and occupation.
7. Diet habits will be analyzed by dietician.
8. Details of physical activity will be assessed by a questionnaire.

Laboratory investigations:

1. Initial OGTT
2. Plasma glucose and HbA1c.
3. Lipid profile
4. Liver function tests
5. Serum amylase and serum lipase
6. Plasma insulin
7. 12 lead ECG.

Review analysis:

1. Review will be done with all clinical and biochemical assessment annually.
2. Evaluation of adherence to prescription will be done at 6 monthly intervals.

Inclusion Criteria:

Subjects with IGT in the age group of 30-55 years (n=900) will be identified by screening with a standard OGTT.

Exclusion Criteria:

1. Known diabetes
2. Pregnant women
3. Alcohol abuse
4. Transferable jobs.
5. Subjects with major illness like cancer, hepatic or cardiac diseases.