Objectives To investigate the association between having osteoarthritis (OA), hypertension, or diabetes, either alone or in combination, and receiving guideline-recommended exercise or weight-reduction advice. Design Cross-sectional study. Methods We applied logistic regression to analyse self-reported data from the 2017 Danish National Health survey (DNHS). We calculated the proportions and odds ratios of receiving exercise advice and weight-reduction advice (if BMI>30) from the general practitioner (GP) in seven patient groups: those with OA or hypertension or diabetes or any combination of these diseases. Results From the 183,372 DNHS responders, we included 71,717 patients (≥45 years) who reported consulting a GP during the previous year. Among patients with only one disease, those with OA were least likely to receive exercise advice (13%, 1441/11,024) and weight-reduction advice (27%, 504/1877), while those with diabetes were most likely to receive these advice (32%, 387/1200 and 55%, 160/289, respectively). For OA-only patients, the adjusted odds ratios of receiving exercise advice and weight-reduction advice were 1.4 (95% CI 1.3 to 1.5) and 1.6 (95% CI 1.4 to 1.8), respectively, compared with patients with none of the three diseases. For diabetes-only patients, the adjusted odds ratios were 4.2 (95% CI 3.7 to 4.7) and 5.4 (95% CI 4.2 to 7.0), respectively. Conclusion Few patients with OA self-reported having received guideline-recommended exercise advice, or weight-reduction advice if obese, from their GP. Furthermore, patients with OA were less likely to report having received these advice compared with patients with other chronic diseases.