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Exams and Tests for Diabetic Feet

As a diabetic, it is important for you to be knowledgeable about practices that help decrease your risk of developing diabetic foot complications. One such practice is the comprehensive foot exam done by your healthcare provider annually and more frequently if you have neuropathy or poor circulation. You should play an active role in ensuring that important exams and tests, that can help reduce diabetes complications, are part of your diabetes care plan. Always be ready at the doctor’s office for a comprehensive foot exam by taking off your socks and shoes. And if you healthcare provider still doesn’t check your feet, ASK THEM to do so. Based on your comprehensive foot exam, your healthcare provider will determine if you need additional investigations.

1.0 Comprehensive Foot Exam:

Components of the comprehensive foot exam are:

1.1 Clinical History:

As the first step in comprehensive foot exam, your healthcare provider will review your current/past medical history with you.

  • Your doctor will ask you about symptoms of neuropathy and peripheral vascular disease (for symptoms see article “When to see your doctor”), your smoking history, changes in your foot since last exam, any footwear problems, your dietary habits and your last HbA1c level.
  • It is important for you to be very specific especially about neuropathy symptoms and not miss anything out. Best thing is to write them down before seeing your doctor.

1.2 General Physical Exam:

During the exam your healthcare provider will assess your general physical health and check your blood pressure and heart rate.

1.3 Neurological/Sensory Exam:

This is a crucial part of the foot exam. Your healthcare provider will test your nerves by checking different sensations in your feet and see how well you respond. Because different nerves are involved in transmitting different sensations, your doctor can pin point exactly which nerves are affected by diabetes. Your doctor will perform five simple tests to check your nerves.

Monofilament Test:

This test assesses the touch sensation and utilizes a flexible nylon filament also known as monofilament. Your healthcare provider will touch your feet at various locations using different thickness monofilaments and ask you if you can feel the filament touching your feet. If you can feel a thin filament, your nerves are intact and you’ll be able to feel anything touching your feet. But if you can’t feel the thicker monofilament, there is some degree of nerve damage.

Pinprick Test:

Your healthcare provider will prick your foot with a pin to see if you can perceive the touch and pain associated with pricking. If not, nerve damage is present.

Tuning Fork Test:

This test assesses your vibration sensation. In case of nerve damage, you’ll not feel the vibrating tuning fork when it‘s held against the tip of your big toe.

Vibration Sensation Test (using a Biothesiometer):

It is a hand held vibrating probe. The intensity of the vibrations can be increased by turning a dial. It is also placed against the tip of the big toe and the reading on the dial (0-50 volts) is noted when you first start feeling the vibrations. In young individuals, the reading is low whereas in older individuals and in people with nerve damage the reading is high, usually greater than 40 volts.

Ankle Reflex Test:

This is tested using a clinical hammer. In case of nerve damage, the reflex will be absent.

Temperature Sensation Test:

Your doctor will test your temperature sensation by touching your foot skin with a hot and cold object and see how well you can feel it.

1.4 Vascular Exam:

Your healthcare provider will check the blood circulation in your feet by doing these tests.

  • Checking Pulses in your Feet
    Your doctor will check two pulses in your foot- one that runs down the front of your foot called dorsalis pedis artery pulse and the other located behind the ankle on the medial side of the foot called the posterior tibial pulse.
  • Non-Invasive Vascular Tests
    In most cases, palpating the pulses is all that is required for vascular assessment. But if the pulses are weak or absent, your healthcare provider will perform non-invasive vascular tests (discussed below).

1.5 Musculoskeletal Exam:

Your healthcare provider will check your muscle strength and tone, joint mobility, bunions, any gross deformities such as claw toe, hammer toe, charcot foot etc.

1.6 Skin and Nail Exam:

Your healthcare provider will examine your skin and nails for these conditions.

  • Condition of Skin
    Sores, ulcers, maceration, swelling, redness, corns, calluses, dryness.
  • Condition of Nails
    Ingrown nail, yellow discoloration.

1.7 Footwear Assessment:

Your healthcare provider will do a footwear assessment to see if it’s a proper fit and the right shoe for your foot type. 

2.0 Investigations for Diabetic Foot:

Diagnostic tests for diabetic foot are individualized depending on your symptoms and findings on comprehensive foot exam. Let’s discuss these tests in terms of what issue they intend to clarify.

2.1 Assessment of Diabetic Peripheral Neuropathy:

Your healthcare provider will usually establish the diagnosis of diabetic neuropathy based on your symptoms and foot exam findings. Special tests are sometimes done to confirm this diagnosis. Most commonly used are Nerve Conduction Study and Electromyography. Before going for the tests, make sure you don’t put any lotions or oils on your arms and legs.

Nerve Conduction Study

measures the electrical activity of your nerves. It determines how well and how quickly the nerves conduct electrical impulses. Small electrodes are placed on the skin of your hands or feet near the area of the nerve and a machine delivers a gentle electrical impulse. The impulse produces a visual signal on a computer monitor and when analyzed, it can provide information about the condition of your nerves.

Electromyography (EMG)

This test is often conducted along with Nerve conduction study. A very small needle is inserted in the muscle which then measures the electrical activity of that muscle. This might be a little uncomfortable for some people but is tolerable. If nerves are damaged and not sending signals to the muscles, that would show up on the EMG.

2.2 Assessment of Peripheral Arterial Disease:

Your healthcare provider will perform special tests for peripheral arterial disease if you’re having symptoms such as calf pain while walking (claudication), rest/night pain and absent/decreased foot and leg pulses on physical exam.

Non-invasive Vascular Tests:

This includes ankle/brachial index (ABI), Duplex Ultrasound and transcutaneous tissue oxygen studies.

Ankle/Brachial Index (ABI):

ABI is the ratio of blood pressure in the ankle to the blood pressure in the arm (measured in brachial artery). Normally blood pressure in your ankle and arm should be almost equal. In peripheral arterial disease, due to narrowing of arteries, the blood pressure in the ankle is almost half of that in the arm (or lower).

Duplex Ultrasound/Scan:

After determining the presence of vascular disease, a Duplex scan is done to locate the blockage and assess its severity by measuring the speed of blood flow. It is done using a hand held Doppler device placed on the skin over the artery.

Transcutaneous Tissue Oxygen Studies:

Your doctor will place a patch on your skin which will measure the amount of oxygen in your blood. This test can be used as a predictor of healing of foot ulcers. Value less than 30 mmHg is associated with poor healing of wounds.

Conventional Angiography:

This is an invasive vascular test that is mainly done to plan intervention. Angiogram is done in preparation of surgery to improve circulation. A catheter is inserted through the artery in groin and contrast material injected which highlights the blood vessels on an x-ray image. It allows the vascular surgeon to see the exact location of the blockage and plan the bypass procedure accordingly. Major risks associated with Angiography are related to the puncture of artery in the groin and use of contrast material.

2.3 Assessment of Infection:

When infection is suspected in a diabetic foot, your healthcare provider will always do a blood test and wound culture and sensitivity testing.

Blood Tests:

such as complete blood count (CBC). In case of severe and serious infections, white blood cell count can be very low or very high. Depending on the severity and spread of infection, your healthcare provider may also order kidney function test, liver function test, blood electrolytes, erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). ESR and CRP are usually increased in the presence on an infection but can be normal. Blood glucose control generally deteriorates during an infection causing high blood sugar levels.

Wound Culture:

If an infection is suspected, your healthcare provider will send cultures from the deep part of the wound to determine the type of infection and the organisms causing it. Sensitivity testing is done along with cultures to see which antibiotics are best for eradicating that infection.

Imaging:

such as X-rays, CT Scans and MRI. X-rays are done to determine the presence of bone infection (osteomyelitis), foreign bodies and gas in soft tissue. If the X-ray is negative but infection is suspected clinically, your healthcare provider will order a Bone Scan, MRI or CT. These test modalities are much more sensitive than a plain X-ray in diagnosing infections.

2.4 Assessment of Charcot Arthropathy:

Imaging:
X-rays will show abnormalities in all stages of Charcot Arthropathy. But sometimes, it is normal in Stage 1. In that case, your healthcare provider will order a MRI or nuclear medicine scan which is more sensitive that a plain X-ray.

2.5 Assessment of Metabolic Status:

This includes:

  • Fasting and Random Blood glucose level
  • HbA1c- to assess average blood glucose level over the preceding 3 months.
  • Blood urea and creatinine- to assess kidney function.
  • Blood Electrolytes

In conclusion, as a diabetic it is very important for you to learn as much as possible about routine diabetic foot care as it plays the biggest role in preventing foot ulcers.

Diabetes and Foot Care … read more:

By |2019-02-03T18:47:22+00:00July 30th, 2013|Diabetes Health|0 Comments

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