Early action starts under the skin

Chronic high blood sugar damages the lining — the endothelium — of small vessels, and the resulting microvascular dysfunction is detectable early, already in prediabetes [2]. Our focus is on providing the tools to measure how well these tiny vessels function, ensuring that when care is available, clinicians can spot early warning signs long before complications become visible.

Early action, before it shows

Diabetes affects the microcirculation long before visible problems such as foot ulcers appear. Endothelial damage gradually impairs the ability of small vessels to increase blood flow when tissue needs more oxygen and nutrients.

From the outside, a foot can look fine. The skin is intact, and pulses may be present. But underneath, the microcirculation is losing its reserve [3] — its capacity to respond to pressure, injury, or infection is shrinking.

Combined with reduced sensation from neuropathy, this is a dangerous situation. A blister, a tight shoe, or a minor cut may go unnoticed, and a wound that would heal within days in a healthy person can heal slowly, or not at all, in someone with diabetes.

Visual inspection only looks at the surface of the skin, and pulse palpation tells us whether blood reaches the foot through the larger arteries, but neither says much about the small vessels where healing occurs. Ankle-brachial index (ABI) is a valuable screening tool, but it has known blind spots in people with diabetes [4] [5].

Calcified, stiff arteries can’t be compressed properly by the cuff, which can make ABI look normal or even high. And because ABI measures pressure at the ankle, it cannot detect disease further down in the foot or in the microcirculation. Either way, the result can hide a foot that is poorly perfused where it matters: in the skin.

We explored this in more detail, with a patient case, in last year’s World Diabetes Day post, Uncovering the hidden side of diabetes.

Early action can mean measuring what the eye can’t see, while there’s still time to act. Microcirculation can be assessed noninvasively, using several guideline-recommended methods [5] [6].

• Transcutaneous oxygen pressure (TcpO2) indicates how much oxygen actually reaches the skin. It helps judge healing potential and whether a patient may need referral for revascularization.
• Skin perfusion pressure (SPP) measures the pressure needed to restore blood flow in the skin’s small vessels. It isn’t affected by calcified arteries the way ABI can be.
• Perfusion imaging shows blood flow across an area as a real-time color map. It makes perfusion differences visible.

For clinicians who treat people with diabetes, early action can start with three simple questions:

• Does this patient’s ABI tell the whole story? If the arteries may be calcified, a normal value isn’t necessarily reliable.
• Is the patient’s perfusion getting worse? A baseline microcirculation measurement reveals change between check-ups.
• Why measure if the patient has no wounds? For high-risk feet, the best time to assess perfusion is while the skin is still intact.

As I mentioned at the beginning of this post, Perimed focuses on measuring small-vessel function, building solutions that reveal early warning signs long before complications become visible. If you’d like to dig deeper into the research, I recommend watching our webinar with Professor Houben, who is part of the Maastricht study [2]: Microvascular dysfunction as an early marker of cardiometabolic diseases. The Maastricht Study includes a broad set of measurements, including skin hyperemic response, which we refer to as laser Doppler with heat. After measuring a baseline perfusion value, this protocol assesses the vasodilatory response as a thermostatic laser Doppler probe heats the skin, measured as a percentage increase from baseline or other parameters such as response time. For more on this protocol, I refer you to our blog post: The power of combining laser Doppler with TcpO2 — one protocol, multiple insights.

If you’d like to learn more about the relevant solutions we have developed to deliver insights for early action, check out PeriFlux 6000, which supports recommended SPP, TcpO2, and Laser Doppler with heat, and our perfusion imager, PeriCam PSI, which provides real-time color maps.