Our society is currently facing an epidemic of diabetes and heart failure. Historically, certain cardiology treatments, mainly beta-blockers, have been considered ‘dangerous’ in diabetic patients, but the time has come for personalized medicine to be applied in the field of cardiology, especially in heart failure (HF). To determine whether HF treatment should be individualized according to diabetes status, this review of the available randomized evidence was carried out, with special emphasis on treatment-effect modification in relation to diabetes. Based on a large body of evidence in the literature, our review concludes that HF treatment should be the same for diabetic and non-diabetic patients. In concurrence, international guidelines now strongly advocate the use of HF drugs, including beta-blockers, in diabetic HF patients. The benefit of HF treatment is at least as favourable in such patients as in non-diabetic patients on a relative basis. Given the higher risk of events in diabetics, this could translate to an even greater absolute impact of HF treatment in these patients, which should further encourage caregivers to more aggressively manage HF in diabetic patients. To this end, non-cardiologists, including general practitioners and endocrinologists/diabetologists who treat diabetic HF patients, should be considered part of the HF drug optimalization process, including the referral of patients to specialized centres for possible implantable cardiac defibrillators and/or cardiac resynchronization indication assessment.