Whichever ward or department to which a patient with acute active foot disease is admitted, the process of medically stabilising the patient should be consistent. The pathway of resuscitation (airway, breathing, circulation, etc.), as well as local protocols for managing sepsis should always be available and followed. The unwell patient with diabetes and hypotension should have anti-hypertensive medication suspended where relevant, to promote more effective fluid resuscitation. Attention must also be given to aspects of diabetic control. The presence of acute hepatic or renal impairment can reduce drug metabolism, which can result in prolonged drug action. For example, reduced sulphonylurea excretion with moderate renal impairment can be associated with an increased risk of hypoglycaemia, through increased drug action itself, as well as through associated reduced insulin clearance. Other concurrent therapies that a diabetic patient may be taking may risk causing more harm and need to either be withheld or have their doses reviewed (Table 4.2). Often, in the face of acute illness and a presumed state of poor tissue perfusion, with or without a rise in serum lactate, the drug metformin is suspended. This is due to concerns of increasing the risk of lactic acidosis. Also, if it is likely that there will be a need for contrast-based investigations within the next 24–48 h, metformin should be stopped (see Chap. 6).

Whilst it is highly likely that hyperglycaemia in a patient with acute diabetic foot disease is largely as a consequence of acute sepsis, consideration should always be given to other potentially confounding issues that may need addressing (Table 4.3). In particular, the presence of the emergency states of either diabetic ketoacidosis or hyperglycaemic hyperosmolar state must be excluded, both of which can be a further consequence of acute sepsis in a diabetic patient and require specific treatment protocols to be followed.

It is not uncommon for the acute foot patient to either have their usual insulin regimen or doses adjusted or find themselves commenced on an intravenous insulin infusion (previously referred to as a ‘sliding scale’) to achieve relative normoglycaemia promptly. A variable rate intravenous insulin infusion (VRIII) is used as a means to achieve improved blood glucose control. It is indicated for use in acutely unwell patients, those anticipated to have a long fasting period (two or more meals) or in poorly-controlled diabetes. The convention is to draw up 50 units of actrapid (fast-acting insulin) in 49.5 mL of 0.9 % sodium chloride solution. This is then infused through a syringe pump, alongside a glucose-based fluid (e.g., 0.45 % saline with 5 % glucose and 0.15 % potassium chloride), which is administered using a volumetric infusion pump. The infusion rate of insulin (units/hour) is determined by bedside hourly capillary blood glucose measurement and is likely to be variable. The rate of fluid infused is set to deliver the hourly requirements of the patient. Hypoglycaemia is a common side effect of an insulin infusion. Great care must be taken with regular blood glucose monitoring for patients on an insulin infusion, so as not to cause hypoglycaemia. Local hospital protocols should be followed in all cases of hypoglycaemia in the diabetic patient. Maintaining good blood glucose control during the acute phase of infection and subsequent recovery will do much to promote immune system activity and better wound healing.