Based on this clinical development shortly after major surgery, sepsis due to intra-abdominal leakage was suspected, and the patient underwent an acute re-laparotomy. However, no abnormalities were found.
Further analysis of the metabolic acidosis revealed a high anion gap (29 mmol/l) and mild hyperglycaemia (13 mmol/l). Urine analysis showed the presence of ketones >5 mmol/l, in particular the 3-OH-hydroxybutyrate level was 5.2 mmol/l (N <0.3 mmol/l).
Based on these findings the diagnosis dapagliflozin-associated DKA was made, with just a mild level of hyperglycaemia. Although the mechanism of SGLT2-associated DKA is not fully understood, the clinical picture has been described previously as a complication of dapagliflozin. Dapagliflozin was discontinued immediately.
The DKA was treated according to the national guidelines with 2000 ml/24 h of intravenous glucose 10% and insulin 1 IU/h, in combination with suppletion of 10-20 ml/h of potassium chloride. Within hours, his clinical condition as well as the biochemical parameters improved. Eight hours after the initiation of the treatment, the plasma pH increased from 7.02 to 7.35. Around surgery and during the DKA, plasma glucose concentrations ranged from 9-13.5 mmol/l. After two days, the patient could be discharged in a good clinical condition.

Discussion
This case report describes a patient with DM2 and severe ‘non-classic’ DKA, which we consider a complication of the use of dapagliflozin in combination with ileus, and consequently surgery. SGLT2 inhibitors are a relatively new class of oral antihyperglycaemic agents. Recently the Dutch College of General Practitioners (NHG) standard for the treatment of DM2 was revised to the extent that the use of SGLT2 inhibitors has become even more prominent, in particular in patients with a high cardiovascular risk. Thus, an increase in the use of SGLT2 inhibitors is likely to occur.[5] SGLT2 inhibitors lower blood glucose by blocking the reabsorption of glucose in the proximal renal tubule, thereby promoting glycosuria. Thus, this process is insulin-independent since it relies purely on tubular filtration of glucose.[3] The most important side effects of dapagliflozin are hypoglycaemia if used in combination with sulfonylurea or insulin and genito-urethral infections due to glucosuria. In addition, the development of DKA has been reported before.

Although the exact mechanism of SGLT2-associated DKA is not fully understood, some postulations regarding its mechanisms have been made.[6] By reducing the plasma glucose concentration through the process of insulin-independent glucosuria, the secretion of insulin by pancreatic beta-cells is evenly reduced, thereby increasing a ketotic metabolic environment by stimulating lipolysis and ketogenesis. In addition, inhibition of SGLT2, which is present in the pancreatic alpha cells, possibly increases the concentration of glucagon, the primary counter-regulatory hormone, causing an increase in the insulin-to-glucagon ratio, inducing ketogenesis and glycogenolysis.[6] The latter process may be part of the explanation of the mild hyperglycaemia in our patient.

Furthermore, most patients with end-stage DM2 lower their exogenous insulin dose after initiation of SGLT2 inhibitors, thereby further reducing the circulating insulin levels and putting them at even more risk of ketosis.[6] Since our patient was not using exogenous insulin, this mechanism could not have played a role. Nevertheless, in the light of the significantly increased use of SGLT2 inhibitors over the past few years, the incidence of DKA is relatively low, suggesting the need for additional factors to induce DKA. Since various pathophysiological mechanisms are postulated for the development of DKA by SGLT2 inhibitors, its potential causes are evenly multifactorial. Apart from ‘spontaneous’ development of DKA, a number of triggering factors have been described, such as gastrointestinal diseases, fasting, the use of a low-carb diet or after surgery.

Whereas ‘the classic DKA’ is generally accompanied by high or even extreme hyperglycaemia, SGLT2-associated DKA is usually accompanied by euglycaemia or, as in our case, only mild hyperglycaemia. The blood glucose level observed during DKA in patients on SGLT2 inhibitors occurs as a result of the balance between endogenous glucose production and renal glucose clearance. Thus, if the blood glucose concentration tends to increase by a relative lack of insulin, the excretion of glucose can increase substantially under the use of SGLT2 inhibitors, thereby causing relatively normal blood glucose concentrations. Other factors such as the presence of physical stress due to the surgical intervention may play an additional role.

In addition to metabolic dysregulation, the use of SGLT2 inhibitors can cause haemodynamic dysregulation as well.[7] By stimulating the secretion of sodium to the distal tube, the intra-glomerular pressure decreases.[3] In combination with osmotic diuresis, a decrease of the intravascular volume, low blood pressure and a lower preload and afterload of the heart can develop, which can lead to the development of ‘shock’, as in our case.

In daily practice it is important to realise that all SGLT2 inhibitor treated patients presenting with signs or symptoms of developing DKA, such as nausea and/or vomiting, should be monitored for DKA even during euglycaemia. It can be helpful to keep close track of the fluid balance in order to prevent dehydration. Particularly in situations of gastrointestinal diseases, fasting, postoperatively or during low-carb dieting, patients are prone to develop ‘non-classic’ DKA, as in the described case. Discontinuing the use of dapagliflozin preoperatively and/or during fasting could be considered. If DKA is diagnosed, the SGLT2 inhibitor should be discontinued, and the DKA should be treated according to traditional guidelines, which are similar to the treatment of ‘classic DKA’.

In conclusion, doctors should be aware of the fact that SGLT2 inhibitors can cause DKA, even during euglycaemia, in particular in situations with low carbohydrate state such as after fasting or during severe illness, or postoperatively.

Disclosures
All authors declare no conflict of interest. No funding or financial support was received. Informed consent was obtained from the patient for the publication of this case report.