Perioperative hyperglycemia is associated with higher risk of perioperative complications, worsened neurologic outcomes, shorter survival and increased mortality in patients undergoing craniotomy and tumor resection. It has been shown that even mild hyperglycemia in the perioperative period  is associated with poorer outcomes. However, whether this is due to pre-existing diabetes mellitus or stress induced hyperglycemia has not been studied.

It is well established that perioperative hyperglycemia is common both in diabetic and non-diabetic patients undergoing craniotomy for tumor resection. Although the underlying mechanisms of perioperative hyperglycemia in the neurosurgical patients are poorly understood, several factors such as the use of corticosteroids and the stress response to brain surgery are believed to play an important contributing role.

Craniotomy is associated with multiple steps with significant stress response such as induction of anaesthesia, intubation, skull pin placement, skin incision, craniotomy, dural incision and extubation.

In the neurosurgical patient, the stress response due to autonomic, hormonal and metabolic changes induced by surgery and anaesthesia are dependent both on the extent and duration of the procedure and is not the same for each patient. 

However, there is not enough literature focusing on distinguishing between Stress induced hyperglycemia (SHG) and diabetic mellitus (DM) among this population and its effect on perioperative outcomes. Glycosylated haemoglobin (HbA1C) which is commonly used to assess pre-operative glycemic status is an estimate of chronic glycemic control and it is not affected by acute illness. Recently, we have multiple glycemic parameters to assess stress induced hyperglycemia such as glycemic gap (GG), stress hyperglycemia ratio (SHR) and Glycemic Stress Index (GSI). These measure the glycemic variability which reflects the magnitude of glycemic excursions, which are in-turn are affected by the stress of surgery and are known to be associated with poor outcomes in critical illness.

In our study, we would like to study the correlation between multiple glycemic parameters which are reflectors of stress induced hyperglycemia with post-operative and intra operative outcomes in patients undergoing elective craniotomy.