Here is the design of a clinical trial:

Official Title: A Randomised Controlled International Multicentre Study Evaluating Changes in Metabolic Syndrome in Smokers With Type 2 Diabetes Mellitus After Switching From Tobacco Cigarettes to Combustion-Free Nicotine Delivery Systems: DIASMOKE Study

Included conditions:
- Cardiovascular Risk Factor
- Diabetes Mellitus, Type 2

Study Armgroups:
- {'label': 'Standard Arm (Arm A)', 'type': 'ACTIVE_COMPARATOR', 'description': 'Participant continues smoking their own cigarette brand.', 'interventionNames': ['Other: TOBACCO CIGARETTES']}
- {'label': 'Intervention Arm (Arm B)', 'type': 'ACTIVE_COMPARATOR', 'description': 'Participant switches to using C-F NDS', 'interventionNames': ['Other: COMBUSTION-FREE NICOTINE DELIVERY SYSTEMS (C-F NDS)']}

Interventions:
- {'type': 'OTHER', 'name': 'TOBACCO CIGARETTES', 'description': 'Participants in Arm A will continue smoking their own cigarette brand as usual.', 'armGroupLabels': ['Standard Arm (Arm A)']}
- {'type': 'OTHER', 'name': 'COMBUSTION-FREE NICOTINE DELIVERY SYSTEMS (C-F NDS)', 'description': 'Participants in Arm B will trial and familiarize with their allocated products to select the C-F NDS of their preference. They will be trained and counselled on the chosen C-F NDS; participants will also have the option to try and choose among a selection of either 3 e-liquids or 3 tobacco sticks (depending on the C-F NDS they have chosen). Participants wishing to use a heated tobacco device (HTD) will receive one kit and a full 1 week supply of tobacco sticks of their choice (they will receive a number of tobacco sticks/day corresponding to the number of cigarettes smoked at baseline); those wishing to use a vaping product will receive one vaping kit and a full 1 week supply of e-liquids of their choice (they will receive 4 x 10 ml refill containers).', 'armGroupLabels': ['Intervention Arm (Arm B)']}

Primary Outcomes:
- {'measure': 'Change in Metabolic Syndrome Prevalence', 'description': 'Percentage (%) change in Metabolic Syndrome Prevalence', 'timeFrame': 'Changes in the prevalence of Metabolic Syndrome from baseline will be assessed at 3 months, 6 months, 1 year, and 2 years'}

Please estimate the sample size based on the assumption: 
Significance level was set at 5% (α=0.05), with a power of 80% (β=0.20). An estimated 50% proportion of patients randomised to C-F NDS are expected to achieve sustained reduction in cigarette consumption of at least 80%. The expected number of patients in both arms withdrawing from the trial over 2 years is estimated at 20%.
Powering and sample size calculation
          For this study, the following input assumptions were considered:
          
            
              The absolute reduction in MetS prevalence following substantial smoking cessation is expected to be 15%, based on the results of a range of lifestyle modification interventions.24â28

            
            
              The baseline prevalence of MetS in T2DM is expected to be 70%.29â32

            
          
          Sample size was calculated on the basis of demonstration of superiority, using an assumption of normal distribution, as described by Pocock.33 Significance level was set at 5% (Î±=0.05), with a power of 80% (Î²=0.20). On this basis, the minimum number of patients with analysable data required is 160 per treatment arm (N).
          Further assumptions at the planning stage included an estimated 50% proportion of patients randomised to C-F NDS who are expected to achieve sustained reduction in cigarette consumption of at least 80% for the duration of the study (%SusRed).34â38

          The adjusted number of patients in the intervention arm (N2) was therefore increased to 320:
          N2=N/%SusRed=320 (N2 indicating the final number of patients required after taking into consideration the 50% sustained reduction figure).
          Additionally, the expected number of patients in both arms withdrawing from the trial over 2 years is estimated at 20%.39â41 The total number of patients recruited to each treatment arm was therefore increased by this amount:
          Intervention arm: 320Ã1.2=384.
          Control arm: 160Ã1.2=192.
          Total patients both arms=576.
          In order to reach the target sample size patients with diabetes will be informed about the potential benefits of switching to C-F NDS as well as the ability to report their health problems to their site investigator via a mobile application.