The identification of higher forefoot temperatures associated with peripheral arterial disease in type 2 diabetes mellitus as detected by thermography

Aims
The purpose of this study was to investigate whether heat emitted from the feet of patients with type 2 diabetes (DM) and peripheral arterial disease (PAD) differed from those with type 2 diabetes without complications (DM).
Methods
A non-experimental, comparative prospective study design was employed in a tertiary referral hospital. Out of 223 randomly selected participants (430 limbs) who were initially tested, 62 limbs were categorized as DM + PAD and 22 limbs as DM without PAD. Subjects with evidence of peripheral neuropathy were excluded. Participants underwent thermographic imaging. Automatic segmentation of regions of interest extracted the temperature data.
Results
A significant difference in temperature in all the toes between the two groups was found (p = 0.005, p = 0.033, p = 0.015, p = 0.038 and p = 0.02 for toes 1–5 respectively). The mean forefoot temperature in DM + PAD was significantly higher than that in DM (p = .019), with DM + PAD having a higher mean temperature (28.3 °C) compared to DM (26.2 °C). Similarly, the toes of subjects with DM + PAD were significantly warmer than those of subjects with DM only.
Conclusions
Contrary to expectations the mean toe and forefoot temperatures in DM patients with PAD is higher than in those with DM only. This unexpected result could be attributed to disruption of noradrenergic vasoconstrictor thermoregulatory mechanisms with resulting increased flow through cutaneous vessels and subsequent increased heat emissivity. These results demonstrate that thermography may have potential in detecting PAD and associated temperature differences.