A Phase 4 interventional study of Metformin and Placebo in Intellectual Disability, Developmental Disability and Obesity, sponsored by Centre for Addiction and Mental Health. Recruiting at 1 site in Canada. Open to participants aged 16 Years to 65 Years. Per ClinicalTrials.gov, last updated 2026-03-31.
Sponsored by Centre for Addiction and Mental Health · Phase 4, Interventional, and Treatment
People with IDD (intellectual and developmental disability) have very high rates of obesity and die prematurely from cardiometabolic disease. While antipsychotics contribute to this problem, their use is necessary and appropriate in a significant subgroup of individuals with IDD. Exercise and diet interventions have limitations and may not be sufficient, requiring effective adjunctive pharmacological approaches to target obesity and related comorbidities in IDD. However, persons with IDD treated with antipsychotics are systematically excluded from clinical trials hindering development of evidence to help guide safe and effective treatment of these comorbidities. Moreover, evidence from other disorders cannot be extrapolated to IDD given inherent biological differences between disorders. This trial will address the identified gaps, which extend beyond cardiovascular morbidity and negatively impact psychosocial outcomes, in a hugely underserviced population.This is the the first RCT (randomized control trial) to examine the efficacy of metformin in overweight or obese adults with IDD who have experienced antipsychotic-induced weight gain. By generating efficacy data for a very accessible and scalable intervention, allows for guideline and implementation strategies to address a recalcitrant health problem.
387 studies on the registry are indexed under Intellectual Disability; 105 are open to participants now.
This study's planned enrollment of 100 is above the median of 58 across 248 interventional studies indexed under Intellectual Disability.
Browse Intellectual Disability studies →Centre for Addiction and Mental Health is the lead sponsor of 339 studies on the registry; 51 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Females of child-bearing age must be on one of the following regular :
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
A blood test of average blood sugar over the past two to three months, given as a percentage or in mmol/mol. 6.5% (48 mmol/mol) or more is the usual threshold for diabetes, normally confirmed by a second test.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HbA1c
A blood test of average blood sugar over the past two to three months, given as a percentage or in mmol/mol. 6.5% (48 mmol/mol) or more is the usual threshold for diabetes, normally confirmed by a second test.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
50 participants will be administered oral metformin titrated to a maximum dose of 2000mg/day for 24 weeks.
Drug: Metformin · Behavioral: Lifestyle Intervention
50 participants will be administered an identical oral placebo for 24 weeks.
Drug: Placebo · Behavioral: Lifestyle Intervention
Metformin oral, 2000mg/day, for 24 weeks.
Oral placebo for 24 weeks
Participants from both groups will meet a dietician and a diabetes educator at the study start to obtain advice regarding healthy diet, portion size, and meal planning to improve physical health. All participants will be invited to monthly group meetings to learn skills which will help them in a variety of wellness areas such as physical exercises and diet. Attendance in these sessions will be encouraged but not mandatory, and attendance will be recorded. Fidelity with these interventions will be captured using diet and physical activity questionnaires at RCT start, midpoint and end, and end of open label phase.
Individual's percentage change in body weight
Percentage change in body weight measured in percentage change of pounds (lbs)
Time frame: Weeks 0, 4, 8, 12, 16, 10, 24
Proportion of participants who achieve body weight reduction ≥5%, and ≥10% in each arm
Percentage change in body weight measured in percentage change of pounds (lbs), expressed as a percentage
Time frame: Week 0 and week 24
Between group (metformin vs placebo) absolute change in weight
Absolute change in body weight between metformin and placebo groups measured in pounds (lbs). Calculated by the mean change in weight between the metformin and placebo groups.
Time frame: Week 24
Between group absolute change in waist circumference
Absolute change in waist circumstance measured in centimetres (cm) between metformin and placebo groups. Calculated by the mean change in waist circumstance between the metformin and placebo groups.
Time frame: Week 24
Between group absolute change in BMI
Absolute change in BMI between metformin and placebo groups. Calculated by the mean change in BMI between the metformin and placebo groups.
Time frame: Week 24
Change in whole body insulin sensitivity calculated with Matsuda Index
With the results of the oral glucose tolerance test at Week 0 and Week 24, insulin sensitivity was calculated with the Matsuda index. Insulin sensitivity was calculated with Matsuda index: \[10,000 / √glucose minute 0 x insulin minute 0) (mean glucose (OGTT) x mean insulin OGTT)\]. A higher result is better. In the formula OGTT: oral glucose tolerance test.
Time frame: Week 0 and Week 24
Change in beta-cell function, measured using the Insulin Secretion-Sensitivity Index-2 (ISSI-2)
ISSI-2 is defined as the product of (i) insulin secretion measured by the ratio of the area-under-the-insulin-curve to the area-under-the-glucose curve and (ii) insulin sensitivity measured by the Matsuda index.
Time frame: Week 0 and Week 24
Proportion in each group converting to impaired glucose tolerance, prediabetes, or type 2 diabetes
Measured through the change in HOMA-IR (Homeostatic Model Assessment for Insulin Resistance) derived from the Oral Glucose Tolerance Test (OGTT).
Time frame: Week 0 and Week 24
Change in cardiovascular risk factors assessed by change in C-reactive protein
Measured through the change in C-reactive protein (CRP) assessed at week 0 and week 24. Healthy levels: CRP: Less than 0.3 mg/dL
Time frame: Week 0 and Week 24
Change in cardiovascular risk factor assessed by change in fasting lipids profile
Change in fasting lipid profile (low-density lipoprotein cholesterol (LDL), high-density lipoprotein cholesterol (HDL), and triglycerides) assessed at week 0 and week 24. Healthy levels: LDL: less than 100mg/dL HDL: 40mg/dL or higher Triglycerides: less than 150mg/dL
Time frame: Week 0 and Week 24
Change in cardiovascular risk factor assessed by change in blood pressure
Measured through the change in blood pressure (systolic/diastolic) assessed at week 0 and week 24. A blood pressure range of 110/70 to 120/80 is considered normal.
Time frame: Week 0 and Week 24
Change in visceral and liver fat content
Change in visceral and liver fat content assessed via MRI scans at week 0 and week 24.
Time frame: Week 0 and Week 24
Medication Adherence
Measured through returning of blister pill packs, and assessing number of pills taken.
Time frame: Week 0 to Week 24
Started Feb 2023 (actual). Primary completion is estimated for Mar 2027, 48 months after the start.
How these figures are worked out, and which studies are left out of them.
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
Contact study teamGet an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
Studies of the drug tested here: Metformin
Centre for Addiction and Mental Health →