Type 1 diabetes mellitus (T1DM) is characterized by an increased prevalence of polycystic ovary syndrome (PCOS) with its negative metabolic consequences, including increased cardiovascular risk. Both diseases affect patients, significantly deteriorating the quality of life. During the treatment of patients with T1DM and PCOS, lifestyle modification and increased physical activity resulting in weight reduction should always be recommended. Pharmacological treatment should be applied in accordance with the current standards. In most of these patients metformin alone or with combined oral contraceptive pills could be considered for cycle regulation. In obese patients with T1DM and PCOS glucagon-like peptide-1 receptor agonists (GLP-1 Ras) (liraglutide, semaglutide) and dual glucose-dependent insulinotropic polypeptides (GIP)/GLP-1 RAs (tirzepatide) are regarded as a safe approach. Anti-androgens could also be considered especially to treat hirsutism and hyperandrogenism in women with PCOS. There are relatively limited evidence on anti-androgens in PCOS and we should consider use them in only selected cases. Some other substances may have a positive effect on patients with T1DM and PCOS include inositol, alpha-lipoic acid, folic acid, vitamins (B1, B6, B12, D, K, E, A), chromium and selenium compounds, as well as omega-3 fatty acids. The gut microbiome is also considered as a critical modulator of the predisposition to PCOS and T1DM and may be the future goal of the treatment. The proper treatment of PCOS will translate into a reduction in the severity of typical symptoms and also into the improvement in the metabolic control of diabetes and the patients' quality of life.