The Finger-Prick Sign of Diabetes: An Observational Study Including Dermatoscopic Features

This study aimed to define the clinical features and prevalence of the finger-prick sign in a cohort of persons with diabetes mellitus (DM). One hundred and five consecutive persons with DM attending a hospital diabetes clinic (n = 44) or a dermatology out-patients clinic (n = 61) who performed self-monitoring of blood glucose (SMBG) at least once daily and 105 age- and sex-matched controls were examined for typical prick marks on any of their fingers. The sign was positive (two or more prick marks visible) in 88 participants (84%), with strong positive correlation between the stated daily SMBG frequency and the number of prick marks observed, r = 0.723, P < 0.0001. Prick mark numbers were highest for the ring followed by the little, middle, and index fingers and lowest for the thumb, and varied significantly between the different fingers (P < 0.0001). Overall, prick marks were commoner on the non-dominant hand compared to the dominant hand (P < 0.0001). None of the controls had any visible finger-prick marks. The finger-prick sign is positive in most persons with DM who perform SMBG, particularly in those who test more frequently. It is a pointer to DM that can be clinically useful, particularly in emergencies when a person's medical history is unobtainable.