Neuropad for detecting preclinical diabetic peripheral neuropathy

Neuropad (TRIGOcare International) is a point-of-care test for use in people with diabetes. The test detects sudomotor dysfunction (inadequate sweat production), which may indicate that a person is in the early stages of developing diabetic peripheral neuropathy (DPN). The 10‑minute test is non-invasive and involves applying a single-size plaster to the sole of the foot. The plaster contains cobalt chloride, which changes colour as it absorbs sweat. The colour changing from blue to pink indicates normal sweat production and implies preserved autonomic nerve function. If the plaster stays blue or does not turn fully pink, it is assumed that there is reduced sweating which carries with it an increased risk of diabetic foot complications. The Neuropad test can be done in a clinic by a healthcare professional during a routine foot check, or at home by the person themselves or their carer. Neuropad can be used either as a standalone test or in conjunction with other standard sensory neuropathy testing.

Neuropad is a class I diagnostic device. The cost of Neuropad stated in the company's submission is £7.28 (excluding VAT).

The summary of claimed benefits of Neuropad in the case for adoption presented by the company are that it:

• is simple and can be done at home by the person with diabetes or their carer, or in a clinic by a healthcare professional

• is non-invasive, painless and safe

• provides results in 10 minutes that are easy to interpret

• can detect DPN earlier than monofilament and vibration tests, so is useful for the early identification of people at the greatest risk of complications.

NICE's guideline on diabetic foot problems recommends that adults with diabetes should have a risk assessment for diabetic foot problems at diagnosis, at least every year thereafter, whenever foot problems arise and at the time of any admission to hospital. During the risk assessment, both feet should be examined for any risk factors, including manifestations of DPN, which should be tested using a 10 g monofilament as part of a foot sensory examination. If DPN is detected, a person's risk is classified as being moderate or high (depending on the presence or absence of other comorbidities). This should trigger referral to a foot protection service and more frequent subsequent foot assessments.

NICE's medical technologies guidance on VibraTip for testing vibration perception to detect DPN states that the technology shows potential but more research is needed.

NICE's guideline on diabetic foot problems does not refer specifically to testing for preclinical DPN using, for example, sudomotor function (on which Neuropad is based) or any other modality. Preclinical DPN refers to the early-stage development of the condition before it becomes clinically apparent (see section 4.2).