A Study to Evaluate the Effect of RO7204239 on Insulin Sensitivity and Muscle Composition in Participants With Type 2 Diabetes Mellitus (T2DM) and Overweight or Obesity

The main purpose of this study is to assess the effect of RO7204239 on insulin sensitivity versus placebo in participants with T2DM and obesity or overweight.

Inclusion Criteria: * Participants with T2DM for at least 6 months, treated with diet, exercise and/or metformin alone or in combination with either dipeptidyl peptidase 4 (DPP-4) inhibitor or sodium-glucose co-transporter 2 (SGLT2) at stable dose for the last 3 months prior to study entry and with a HbA1c between ≤ 6.5% and ≤ 10% * Body mass index (BMI) within the range of 27.0 to 45.0 kilogram per meter square (kg/m2) * Stable body weight for the 3 months prior to screening * Participants on lipid-lowering or antihypertensive drugs must be on stable doses for at least 3 months Exclusion Criteria: * Type 1 diabetes mellitus (DM), known latent autoimmune diabetes in adults, or people with an episode of ketoacidosis or hyperosmolar state requiring hospitalisation in 6 months prior to screening * Active proliferative diabetic retinopathy, diabetic maculopathy, or severe non-proliferative diabetic retinopathy requiring acute treatment * Uncontrolled comorbid conditions commonly associated with diabetes (for example, hypertension, hyperlipidaemia) * Severe hypoglycaemia within 6 months prior to screening visit * Current autonomic neuropathy as evidenced by neuropathic urinary retention, resting tachycardia, orthostatic hypotension, or diabetic diarrhea * Have evidence of a significant, uncontrolled endocrine abnormality (e.g., thyrotoxicosis and adrenal crises) * Are currently taking a central nervous system stimulant (e.g., Ritalin-SR), with the exception of caffeinated beverage * Have a known allergy, hypersensitivity, or intolerance to any component of the study treatment (i.e., RO7204239 / placebo) formulation * Blood donation of more than 500 milliliters (mL) within the past 3 months or blood transfusion or severe blood loss within 3 months prior to screening