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Published 11 April 2020
My main obstetric interest is diabetes and gestational diabetes. I was investigating the possibility of a home-test system for a glucose tolerance test, having known for many years known that huge numbers of things we bring people into hospital or a GP surgery for, could be done remotely. Indeed, my telemedicine service, Dr Morton’s – the medical helpline is built upon that principle. COVID-19 has meant that at last remote consultation will become the norm, but more pressingly, we need a way of providing our pregnant women with screening for gestational diabetes without sitting in a hospital for 2 hours, which is how long a glucose tolerance test takes.
So I was introduced to the brilliant James Jackson, founder of Digostics, who has developed a home finger-prick oral GTT system with a blue-toothed result via a down-loaded app. Genius! Sadly only in the early production stage, but definitely to be supported and funded centrally please. We can, however, do a GTT by post, processed in our lab with results back quickly to you via our doctors online if you wish.
As an obstetrician I have looked on in awe at my anaesthetic and physician colleagues who together with all the incredible nurses, ODPs, paramedics…. absolutely every member of the team, have responded with superhuman speed to the COVID-19 crisis. At my hospital I have been immensely impressed by the management team who have facilitated and rolled out a huge plan to be ready for the onslaught of COVID-19 cases, expected to reach a peak over the next 7 days in Guildford. Maternity has been prepared in a similar military fashion and as I started my weekend on call over Easter, I knew that we would provide all women and babies with the care they need, albeit from behind face masks and full PPE if needed. But the disease itself interests me from an academic point of view. It is not like any usual pneumonia or even adult respiratory distress syndrome (ARDS) nor the SARS outbreak in 2006. It seems as if this virus binds to haemoglobin, which lives inside red blood cells, causing a release of free iron, which in itself is toxic, and the haemoglobin then loses its oxygen-carrying capacity. Tissues become starved of oxygen (hypoxic). The ability of each individual to mount an appropriate immune response is also crucial, and not well understood. Indeed, it is sometimes an extraordinary immune response with a so-called ‘cytokine storm’ which worsens the situation.
So why are some people more vulnerable to serious as opposed to mild disease? It is understandable that elderly people in general would be less able to deal with any assault, but I am interested in the possible role of diabetes and as yet undiagnosed glucose intolerance, perhaps with a mildly elevated glycosylated haemoglobin (HbA1c). Maybe even other haemoglobinopathies have a role to play. Is it possible that this is why there are such racial differences in mortality? Seventy percent of the deaths in the USA are black Americans and it cannot have escaped the notice of the UK population that the majority of the tragic deaths amongst the medical and nursing profession are from Southern Asia. We certainly know that raised BMI has more impact on a wide range of pathologies in Asians compared with Caucasians, from the incidence of fetal abnormalities to the incidence of type II diabetes. Black races too have a higher incidence of diabetes compared with Caucasians and there is the additional issue of sickle cell haemoglobin. One in 365 black Americans have sickle cell disease and 1 in 13 have a sickle trait. In this situation where only one sickle gene has been inherited such that there are usually no significant day to day ill-effects, 30-40% of the haemoglobin molecules are abnormal. This could be very important in COVID-19 infection. The difference in mortality between different ethnic groups has been laid at the door of social deprivation and although this undoubtedly plays a part, maybe it is not the whole story.
The Intensive Care and National Audit and Research Centre (ICNARC) published a review of the COVID-19 ITU cases to 4pm on 9 April 2020. They looked at the characteristics of the 3883 admissions and compared them with 5782 historic admissions with viral pneumonia during 2017-19. I have highlighted the things I think are particularly interesting in the table shown above.
It is clear that the vulnerable groups are quite different in this disease compared with a typical viral pneumonia. Black and Asian men are most at risk. Women fare so much better than men. My thoughts go back to the haemoglobin molecule. The study reported in 2006 after the SARS outbreak showed that diabetics and people with ‘ambient hyperglycaemia’ had a higher mortality than those who did not. Maybe glycosylated haemoglobin is more vulnerable to COVID-19 attack? It seems to me that this could be an area where public health and indeed self-help could go a long way. Of course, diet and exercise are key, but knowing that you have glucose intolerance (call it “pre or early diabetes”) could be the driver to sorting out an improved diet, particularly if you are given the right advice. It would be of interest also to have a baseline HbA1c. So, after a great deal of thought this is a test we have decided to launch from Dr Morton’s. It in no way says you will get COVID-19 but it could be really helpful in improving your resilience and general health, and in the longer term, should you be unfortunate enough to contract COVID-19, maybe reduce the severity of your illness. Women who feed their families are key to this! Sorry if that sounds sexist. Some people may even benefit from treatment with an oral hypoglycaemic agent such as metformin. This would depend upon blood glucose profiles during a normal day.
The test is done after fasting from food and any fluid other than water for 12 hours. A tiny blood sample is taken by a simple finger prick and collected into a special vial. A glucose drink (provided as it must contain precisely 75g of glucose) is drunk and then a second test is taken precisely 2 hours later. It is easy to set a timer with your phone or Alexa!
A normal result is defined by the World Health Organisation as a fasting blood glucose of between 3.3 and 5.5 mmol/l and a two hour value of <7.8mmol/l
Haemoglobin is the iron-containing protein contained within red blood cells which is responsible for carrying oxygen to all the organs in the body. If you have too little haemoglobin you are anaemic. If you have a excess of glucose in your blood, it binds to the haemoglobin molecule. This is called ‘glycosylation’. The percentage of your haemoglobin which is glycosylated is an indicator of your blood glucose levels over the past 3 months or so.
This blog was first published on 12/04/2020