Besides myotonia, which clinical feature is commonly seen in DM1 and DM2?

• A. Distal and proximal muscle weakness, facial weakness, early cataracts, endocrine issues
• B. Cardiac arrhythmias and diabetes
• C. Severe spasticity
• D. Pure sensory neuropathy

Answer: (B)

DM1 and DM2 affect multiple body systems beyond the muscles. A frequent nonmuscle finding in both is involvement of the heart’s conduction system, which can lead to arrhythmias or conduction blocks. At the same time, disturbances in glucose metabolism are common: diabetes mellitus is classically seen in DM1 and is also a familiar metabolic feature in DM2 due to insulin resistance. This combination of cardiac rhythm problems with diabetes reflects the widespread systemic nature of both DM types, making cardiac arrhythmias and diabetes the most consistently seen features beside myotonia. The other options highlight features that don’t occur as reliably across both forms (for example, cataracts are more characteristic of DM1, severe spasticity isn’t typical, and pure sensory neuropathy isn’t a defining feature).