NHS Tayside

Erythema is a physiological response to an insult on the skin. One such insult is ultraviolet (UV) radiation, with the resultant erythema also known as sunburn. It is a reddening of the skin as a result of increased blood flow to the area. By controlled exposure to UV radiation, a minimal erythema dose (MED) indicative of threshold erythemal sensitivity to the exposure waveband may be determined - this is determined visually by a trained clinician as the dose of light required to cause a just perceptible reddening of the skin. The MED of a specific patient on a specific skin site is an important measurement - it can allow for determination of initial dose in UV phototherapy, provides an indication of background levels of photosensitivity in diagnostic phototesting and may be influenced by exogenous factors, such as photoactive drugs.
The erythema response has been measured previously using non-invasive hand-held devices for a variety of UV exposures, including narrow-band (NB-)UVB, UVA and UVA1. Typically, the participant will be exposed in the morning (t = 0h) and have a reading taken immediately after. These readings are assessed visually by a trained clinician, or occasionally reflectance devices are used quantify erythema. The participant will then return at the end of the working day (t
8h) for another reading, and again the next morning for another reading (t
24h). This results in large gaps in the knowledge of erythemal response over time.
In this study the investigators aim to characterise the erythema response as a result of UV insult using a wearable erythema device to take continual measurements. This would allow us to more accurately determine the time point of peak erythema, which would inform and potentially change our current practice in reading MEDs. The investigators have previous experience of studies using reflectance devices to measure erythema time course at fixed intervals, however there are still gaps in the knowledge of the time course response of erythema.
There is no expected health benefit to participants in this study, however they may gain a better understanding of their responses to ultraviolet light MED testing. Controlled UV exposures are commonplace in our practice in the Photobiology Unit and it is not foreseen that there are any risks to participation in the study.
The primary objective in this study is to determine when the peak erythema index occurs in a healthy volunteer group. Success of this outcome will help fill in these gaps in the knowledge about the time course of erythema. The secondary objective is to determine if there is any difference in MED and/or peak erythema if the UV exposure is delivered in the morning vs. the afternoon. The outcomes of the research will be 20 sets (2 per participant) of continuous 48-hour erythema measurements.

Treatment of Type 1 diabetes requires daily insulin therapy given by either multiple daily injections or by continuous infusion via a pump. The insulin dose is calculated taking into consideration blood glucose levels, food intake and activity levels, aiming to avoid high and low readings.
The Tandem t:slim X2™ insulin pump has recently become available in NHS Scotland and can link with the Dexcom G6 continuous glucose monitoring (CGM) system.
The Tandem Control IQ hybrid closed loop system is made up of the Tandem insulin pump communicating wirelessly with the Dexcom G6 CGM. The algorithm within the pump then automatically controls the background (basal) insulin infusion rate. Manually delivered bolus insulin is still required for meals. This system is designed to finely tune insulin delivery and increase the amount of time that glucose is in the target range, reducing hypoglycaemia and hyperglycaemia.
Insulin pumps are funded by NHS Scotland, but the Dexcom G6 continuous glucose monitoring system is not, so this hybrid closed loop system is not currently routinely available in NHS Scotland.
The purpose of this study is to gain experience of this system and investigate how effective and acceptable the hybrid closed loop system is for people in Scotland. Participants will be provided with the Dexcom G6 CGM device to link to their current pump to create the hybrid closed loop system for the duration of the study.
30 people with Type 1 diabetes who have been using the Tandem pump for at least one month will be invited to participate.
The study will include a screening visit, a 30 day run-in period, 52 week treatment period and 12 week follow-up period. Diabetes control will be measured using HbA1c and downloaded information from the hybrid closed loop system. Participants will also complete questionnaires and a reflective diary.