The Pre-DICTED (Pre-Diabetes Intervention and Continued Tracking to Ease-out Diabetes) program is a community-based diabetes prevention program. This study aims to test the effectiveness of structured, group-based lifestyle interventions with stepwise addition of metformin, if required, among subjects with pre-diabetes in multi-ethnic Singapore.

The Pre-DICTED program is designed as a randomized, controlled, pragmatic trial. The program targets to recruit up to 846 overweight/obese (BMI ≥23.0) adults (age 18-64) with isolated impaired fasting glucose (IFG), isolated impaired glucose tolerance (IGT), or IFG + IGT in Singapore. The follow-up period will be 3 years.

Eligible subjects will be identified through community, primary care clinics and hospital-based diabetes screening program. Following informed consent, eligible participants will be randomised into the control or the treatment arm.

Participants in the control arm will receive the current standard of care for pre-diabetes which includes counseling on lifestyle modifications and follow up by primary care physicians.

Participants in the treatment arm will undergo a 3-month, locally tailored, group-based lifestyle intervention program (consisting of nutrition workshops, exercise sessions and goal-setting workshop) plus subsequent stepwise addition of metformin for selected participants at the highest risk of progression to diabetes at ≥ 6 months of follow-up. Financial incentives will be awarded to participants who achieve weight lost of ≥5% of baseline weight during follow-up period.

The primary outcome of diabetes incidence will be assessed bi-annually and compared across the study arms. Secondary outcomes will include weight, waist circumference, fasting plasma glucose (FPG), 2-h glucose, HbA1c, physical activity, diet and metformin adherence.

Inclusion Criteria:

1. Singapore citizens or permanent residents

2. Age between 18 and 64

3. Body mass index (BMI) ≥ 23.0 kg/m2

4. Pre-diabetes diagnosed based on:

   1. fasting plasma glucose 6.1 - 6.9 mmol/L (Impaired fasting glucose; IFG) and/or
   2. 2-hr plasma glucose in 75g oral glucose tolerance test (OGTT) 7.8 - 11.0 mmol/L (Impaired glucose tolerance; IGT) (Laboratory tests to be done within 6 months of enrolment)

Exclusion Criteria:

1. Individuals with diabetes mellitus
2. Health conditions impeding participation in lifestyle change programme (e.g. active cancer, recent myocardial event within 6 months, heart failure, chronic kidney disease)
3. Current pregnancy or breast feeding
4. Treatment with medications known to alter glucose tolerance
5. Known allergic reaction to metformin