Aims To investigate whether small nerve fibre degeneration detected using corneal confocal microscopy is associated with cardiac autonomic neuropathy in people with Type 1 diabetes. Methods Thirty‐six people with Type 1 diabetes and 20 age‐ and sex‐matched healthy control subjects were enrolled. Tests to determine heart rate response to deep‐breathing (expiratory‐to‐inspiratory ratio), heart rate response to lying‐to‐stand test (30:15 ratio) and blood pressure response to standing were performed to detect cardiac autonomic neuropathy. Corneal confocal microscopy was performed to assess: corneal nerve density and corneal nerve beadings; branching pattern; and nerve fibre tortuosity. Results Compared with control participants, participants with Type 1 diabetes had fewer (mean ± sd 45.4 ± 20.2 vs 92.0 ± 22.7 fibres/mm2; P < 0.001) and more tortuous corneal nerve fibres (20 participants with Type 1 diabetes vs four control participants had nerve tortuosity grade 2/3; P = 0.022) and fewer beadings (mean ± sd 15.1 ± 3.5 vs 20.6 ± 5.0; P < 0.001). Of the participants with Type 1 diabetes, 11 met the criteria for the diagnosis of cardiac autonomic neuropathy. Corneal nerve density was significantly lower in participants with cardiac autonomic neuropathy than in those without (mean ± sd 32.8 ± 16.4 vs 51.7 ± 18.9 fibres/mm2; P = 0.008). This difference remained significant after adjustment for age (P = 0.02), gender (P = 0.04), disease duration (P = 0.005), insulin requirement (P = 0.02) and neuropathy disability score (P = 0.04). Conclusion This study suggests that corneal confocal microscopy could represent a new and non‐invasive tool to investigate cardiac autonomic neuropathy in people with Type 1 diabetes. Larger studies are required to define the role of corneal confocal microscopy in the assessment of cardiac autonomic neuropathy. What's new? Cardiac autonomic neuropathy is one of the most overlooked but life‐threatening complications of diabetes mellitus. It is possible to improve impaired cardiac autonomic function, especially in the earlier stages of cardiac autonomic neuropathy but, unfortunately, tests currently available for the investigation of cardiac autonomic neuropathy are invasive and/or inaccurate, difficult to perform and time‐consuming. New techniques that allow easier screening for cardiac autonomic neuropathy are therefore required. We show, for the first time, that corneal confocal microscopy can be an effective tool for the clinical diagnosis of cardiac autonomic neuropathy.