 Now, let's move on to the protocol at your institution. It's going to be different for everyone, but there's some baseline research and experience that went into that, and some of that you have to understand. Now, remember, two-thirds of all patients that you will see will be on some form of oral hypoglycemic. Now, there are quite a few of them. I just want to mention two groups, the big one nights, of which we have met foreman. Now, those are sensitizers, so they'll sensitize the body tissues to insulin. And they also decrease glucose production. They have a very low risk of causing hypoglycemia, but they do have a risk of causing lactic acidosis in sensitive patients. For us, as surgeons, we might be worried about the patients with renal insufficiency and sending them to get contrast at radiology. The sulfonylureas, like the second generation gliposide, now these are secretogogs, so they're going to stimulate the release of insulin in those patients that can still produce a bit of insulin. They do have a high risk of causing hypoglycemia, so watch out for them, and their side effect really is weight gain. Now, a quarter of your patients will be on insulin, so those will be the type ones. They require insulin, but many type two diabetics are also on insulin. Now, when a patient is on an insulin regime, it's really trying to mimic the normal physiology. So they'll get a type of insulin just as a baseline. You have a normal basal metabolic rate, even if you don't eat or do much, and that requires some throughput of glucose metabolism. So there's this basal rate, then there's an increased rate of insulin just to take care of the carbohydrate intake that follows meals and to deal with that carbohydrate load. And there's also, from time to time, we also need a bit of rescue therapy, it just might be that the patient ate something abnormal, or they suffer from a bit of infection called flu or cellulitis or something like that. So the baseline insulin, you really can do that as two types. In first world setting, many patients have subcutaneous, continuous infusion pumps, but for the rest of us, there's this long-acting, peakless insulin. So they'll just be a slow, long release, so there won't be any peaks. And really 50% of the daily insulin dose should be of this type. Now for your two diabetics on auto-medication and the insulin, most of them require a bit of higher dose of insulin, because remember they are insulin resistant. And they, together with the other type ones, get a mixed dose. So they'll get a long-acting and intermediate-acting, short and rapid-acting insulin made up as a mixture, and you've got to watch out for the different types that they're on. So what can you suggest to patients or what is usually in these algorithms at your institution? Let's start with a day prior to surgery. Now on that day, they just take their normal dosing. Nothing happens on the day before. There are a few exceptions though, watch out for those. If patients do take an evening dose, remember some patients will just take a one-day dose, but most people will be on at least twice a day dose. For those patients that then take an evening dose and do suffer from nocturnal hypoglycemia. In other words, they do have to get up and eat something during the middle of the night. They can decrease their evening dose. They should actually decrease that evening dose slightly by about, say, a fifth to a third somewhere in that range, just decrease that evening dose. If they are type 2, and they are only on peak-less insulin, that baseline insulin that they take, long-acting insulin. So type 2 are all and only on long-acting. They can emit any kind of evening dose that they take. They can emit any kind of evening dose. The patients type 2, so they're an oral and some mixture of insulin, they can still take that evening dose because they will get that peak before they actually go to bed. So they can still take that evening dose. Evening mix, any type of evening mix, but the patient also suffers from hypoglycemia if their breakfast is delayed, which is going to happen. They're going to have to emit breakfast. They can also decrease their evening mixed dose. So watch out for these patients. Now we get to the operative day. Now no oral or non-insulin drugs should be taken on the day of surgery. So that gets omitted. Now remember, try to operate diabetics in the morning so they're not going to have any breakfast. We also advise patients to bring along their own medication. Now the surgical and aesthetic and nursing staff can actually confirm what the patient's on and it confuses any dosing issues that the patient's not sure of or some trade name problems. It really helps to prevent that confusion. So if it's a very short procedure, you can just emit all their morning doses. They go for the procedure, the glucose is monitored every hour and they can just eat afterwards. Now in any longer procedure or there's going to be a long wait, a long delay, either in getting to the surgery or for them to be able to start eating post-op, they always consider giving these patients intravenous glucose. A diabetic also needs glucose. So they're going to get a glucose-containing intravenous line. Now also with the longer procedures later on in the morning, Van et al worked out a beautifully easy formula, pure algebraic formula they're easy to do. Published in 2009, well worth a read. So it works the following way. So you take the normal interval that the patient takes the regular dose at. Some people, as I mentioned, take an insulin once a day so their dosage interval would be 24 hours. Some patients take insulin twice a day so their dosing schedule is 12 hours. You subtract from that, 24 or 12 or whatever, the estimated fasting interval. So say for instance the patient usually takes their morning dose at eight o'clock. They are only expected to be able to eat by one this afternoon. Their case is at about 11 and they're going to come out of the theater and buy about one o'clock they should be able to eat. So what you would do is this eight to one o'clock, that's five hours. That five, you subtract from that interval time, 24 or 12, just subtract that from the normal interval and divide it by that normal interval. And that gives you the fraction of the morning dose that they should then have. So let's be clear, if they're coming in for a short procedure, first thing in the morning and within an hour or two they'll be able to take, you can just estimate all their glucose. If it's going to be longer before they can eat or longer procedure or longer delay before they get to, you have to give them some insulin in the morning together with putting up a drip for them so that they can get intravenous glucose and for them you are going to give a certain dose and you can work out the fraction of the dose that they would usually take in the morning. So that little algebraic formula there, you'll use that and that works out the fraction of the morning dose which is then given usually as an intermediate acting insular. Now if there's any longer delay or patient has a type of procedure which they are going to be null past afterwards, some abdominal procedure like a colectomy, now we really have to consider putting them on a sliding scale from the get go. Now the sliding scale is very individualized, we usually have these written up as a protocol but there's something that underpins that protocol or algorithm that you have in your unit. It works like this, take about 1800 or 1500 in patients who are more insulin sensitive and you divide into that the total daily dose of insulin. So if they get 35 units per day or 40 units per day, divide that, that becomes the denominator, divide that into your 1800 and that will give you, in milligrams per deciliter, the amount that their blood glucose level will be lowered by giving them one unit of fast acting or rapid acting insulin. Okay I'll say that again. So you take 1800 divided by the total daily units of insulin and that will give you the lowering capacity in milligrams per deciliter, the amount that their blood glucose levels will fall if you give them one unit of act rapid. That is what underpins, because it's different for every patient, underpins a generic sliding scale. Once again you can multiply that value by 0.0555 and that will give you the millimoles per liter. So you can work out by how much you want to decrease that and by that you can work out how much insulin to give them. That is what underpins and that is where you get this generic sliding scale from. Now remember in all these surgical patients you have to regularly check their blood glucose levels, at least every hour. These patients demand more resources, you have to watch them pre-operatively, intra-operatively, post-operatively. Never forget hypoglycemia though in these patients. We know that very tight control patients do suffer from hypoglycemia if they were switched to just normal saline in the IV line. They continue to get some form of insulin. They can get hypoglycemic. Watch out for those. Be ready with 50% dextrose water as a small bolus dose or then just switching over to glucose containing 5% dextrose water for instance. Watch out for fluid shifts. Surgery causes fluid shifts. If patients have high blood glucose levels they're going to have an osmotic diuresis so be on top of their fluid requirements. Be on top of their electrolyte disturbances. Glucose plus insulin will give you a movement of potassium into the intercellular space. So watch out for those disturbances. Very lastly just a few words on hypoglycemia. Now different patients experience hypoglycemia differently at different levels and in each patient different levels on different days might cause hypoglycemia. So it's not this absolute cut off. First of all they'll get this energy response. They'll get hungry, they'll get tremors, they'll get palpitations and then the more important neuronal deficits as the neurons are starved of glucose. And remember your neurons can only burn glucose as an energy source and they can become comatose, delirious, they can get convulsions. Usually all starts off by fatigue though and this does carry morbidity. They can develop damage to the neuronal tissue and even mortality. So if they're awake and they can take early, give them a sugary drink, don't give them tablets containing sugar so you might have a solution creating a solution problem or they might be precipitation. So give them a sugary drink or if they can't take give them intravenous fluid and then monitor the blood glucose levels at least every 15 minutes. So the diabetic patient is important, takes a lot of effort and resources but put that into your diabetic patient and understand why that algorithm works the way it does in your patient and if you have to change it slightly to individualize care, remember these things that I've mentioned in this lecture.