Diabetes and the Surgical Patient

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Diabetes and the Surgical Patient

• Dr. Cathy Code
• October 14, 2008

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Objectives

• Review the various agents used to treat diabetes
• Discuss the impact of surgery on diabetes
• Provide a framework for the preoperative
  assessment of a diabetic patient
• Provide a practical approach to the perioperative
  management of diabetes

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Diabetes

• Common chronic disorder
• Associated with both macrovascular and
  microvascular complications
• More surgical interventions
• A diabetic has a 50 chance of requiring a
  surgery in their lifetime
• 20 of surgical patients have diabetes

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Diabetes

• Complex interaction b/w operative procedure, type
  of anesthesia, and postoperative factors
• Diabetic patient requires careful assessment
  prior to surgery
• Increased length of hospital stay and cost
• Increased risk of periop infection and postop CVS
  morbidity and mortality

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Type 1 DM

• Primarily a result of pancreatic beta cell
  destruction
• Absolute insulin deficiency
• Prone to ketoacidosis
• Autoimmune process vs idiopathic
• Requires ongoing insulin treatment

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Type 2 DM

• Predominant abnormality is insulin resistance
• May be treated with diet, OHG and or insulin
• Others
• Diseases of pancreas
• Endocrinopathies
• Drugs

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Oral Hypoglycemics

• Acarbose
• Alpha-glucosidase inhibitor
• Sulfonylureas
• Insulin secretagogues
• ex. Glyburide (Diabeta), Gliclazide (Diamicron)
• Rapid BG lowering potential
• Meglitinides
• Insulin secretagogues
• ex. Repaglinide (GlucoNorm)

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Oral Hypoglycemics

• Metformin
• Negligible hypoglycemic risk
• CI in renal failure (GFR lt 30ml/min) and hepatic
  failure
• TZDs
• ex. Pioglitazone (Actos), Rosiglitizone (Avandia)
• Avoid in CHF
• ? Association with increased cardiovascular events

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Preoperative Assessment

• Focus on cardiopulmonary risk assessment and
  modification
• CHD more common in diabetics
• Associated conditions
• HTN
• Obesity
• CKD
• Cerebrovascular disease
• Autonomic neuropathy

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Preoperative Assessment

• Key elements
• Type of DM
• Longterm complications
• Baseline glycemic control
• Assessment of hypoglycemia
• Diabetic meds
• Other meds
• Characteristics of surgery
• Type of anesthetic

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Preoperative Testing

• Baseline ECG
• Renal Function
• Hgb A1C
• Determination of chronic glycemic control
• Elevated levels may predict a higher rate of
  postop infections
• Noninvasive cardiac testing if indicated

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Impact of Surgery

• Surgery and anesthesia lead to a neuroendocrine
  stress response
• Counterregulatory hormones
• Epinephrine
• Glucagon
• Cortisol
• Growth Hormone
• Inflammatory cytokines

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Impact of Surgery

• Leads to
• Insulin resistance
• Decreased peripheral glucose utilization
• Impaired Insulin secretion
• Increased lipolysis
• Protein catabolism
• Hyperglycemia and possibly ketosis

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Impact of Surgery

• Varies per individual
• Influenced by type of anesthesia
• GA gt spinal anesthesia
• Extent of surgery
• Major vs minor
• Postoperative factors
• Sepsis, hyperalimentation, steroid use

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Goals

• Maintenance of fluid and electrolyte balance
• uncontrolled DM leads to volume depletion from
  osmotic diuresis
• Prevention of ketoacidosis
• Type 1 diabetics are insulin deficient and
  require continuous insulin administration

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Goals

• Avoidance of marked hyperglycemia
• DKA in Type 1 diabetics
• Nonketotic hyperosmolar state in Type 2 diabetics
• Avoidance of hypoglycemia
• Potentially a life threatening complication
• Cardiac arrhythmias
• Cognitive deficits and neurologic sequelae

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Glycemic Targets

• Exact target unclear
• Limited evidence and lack of controlled trials
  except.
• Coronary bypass surgery, IV insulin to maintain
  BS 5.5-10.0, associated with less sternal wound
  infection and mortality
• Surgical ICU patients with hyperglycemia, IV
  insulin to maintain BS 4.5 6.0, reduced
  mortality and morbidity

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Glycemic Targets

• Meta-analysis of RCTs in JAMA 2008
• 29 RCTs of tight glycemic control in critically
  ill patients in an ICU setting
• No evidence of improved patient oriented outcomes
• Found increased frequency in potentially harmful
  hypoglycemia in patients treated with glucose
  control

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Glycemic Targets

• Otherwise
• Published guidelines collectively propose
  attempting to achieve reasonable normoglycemia
• 2008 CDA guidelines
• Perioperative glycemic levels should be
  maintained between 5.0 11.0
• avoid hypoglycemia
• Grade D, consensus

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Diabetes ManagementEarly perioperative phase

• Several various strategies
• No consensus on optimal therapy
• Aim to have surgery early in am to minimize
  disruption of their management while NPO

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Diabetes ManagementEarly perioperative phase

• T2DM, diet alone
• Usually do not require any therapy periop
• Supplemental short acting insulin (regular,
  humalog, novorapid) may be given by sliding scale
  if levels above target
• Check BS preop and postop
• IV dextrose not required unless insulin is
  administered and patient NPO

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Diabetes ManagementEarly perioperative phase

• T2DM on OHG
• Hold OHG am of OR
• Most patients with good control will not require
  insulin for short surgical procedures
• Short-acting supplemental insulin by sliding
  scale can be used for hyperglycemia
• Restart OHG when patients resume eating
• Hold metformin is patient has developed renal
  impairment

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Diabetes ManagementEarly perioperative phase

• Type 1 DM or insulin treated Type 2 DM
• For short, non complex procedures patients can
  usually continue SC insulin
• Continue long-acting insulin while NPO and on IV
  dextrose
• For patients with tight control or prone to
  hypoglycemia, reduce evening/hs insulin night
  before surgery

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Diabetes ManagementTiming of Procedure

• Minor, early morning procedures, breakfast only
  delayed
• patients can take their insulin after surgery
• Procedures where breakfast and lunch missed
• Omit short-acting insulin and give 1/2 to 2/3 of
  long-acting insulin OR
• Take 1/3 to 1/2 of total morning dose as
  long-acting only OR
• SC insulin pump, continue basal rate OR
• Start dextrose containing IV solution

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Diabetes ManagementTiming of Procedure

• Long and complex procedures
• IV insulin is required for Type 1 diabetics and
  Insulin requiring Type 2 diabetics
• Safe
• Easily titrated with a short ½ life (5 10
  minutes)
• Usually started morning prior to surgery
• IV insulin infusion algorithms

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Diabetes ManagementLate postoperative phase

• Preoperative diabetes treatment can be reinstated
  once the patient is eating well
• Metformin should not restart in renal insuff
• Sulfonylureas should only be started after
  patient eating well, consider stepwise approach
• Avoid TZDs in CHF or problematic fluid retention

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Diabetes ManagementLate postoperative phase

• Insulin infusions should be continued until
  solids well tolerated then switch to SC insulin
• For patients on SC insulin, continue IV dextrose
  until patient eating well

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Sliding Scales

• Often used to correct elevated levels
• Problematic if used as the sole method of
  diabetic treatment
• Reactive process, causes wide fluctuation in
  serum glucose
• Should never be the sole method of treatment in
  T1DM due to risk of ketosis

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Example - standard

• Regular, Humalog, Novorapid Insulin, TID, ac
  meals

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Example Insulin sensitive

• Elderly, lean patients or individuals with renal
  or liver dysfunction

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Example Insulin resistant

• Obesity, treatment with glucocorticoids

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Special Considerations

• Glucocorticoids
• Used to treat many disorders, given in stress
  doses perioperatively
• Can worsen existing DM and trigger hyperglycemia
  in others
• Augment hepatic gluconeogenesis, inhibit glucose
  uptake, and alter receptor function
• 2 to 3 fold increase in total daily insulin can
  be required with stress doses

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Special Considerations

• Hyperalimentation
• TPN
• increase blood glucose
• Increase basal insulin, add insulin to TPN
• NG feeds
• Either a IV insulin infusion or BID long-acting
  insulin sliding scale
• Make sure to change insulin if feeds changes to
  bolus

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Case examples

• Case 1
• Mr S, 58 yr old man with newly dxd colorectal Ca
  
• Scheduled for Right Hemicolectomy
• Hx of T2DM maintained on metformin and Novolin
  NPH 16u SC qam and 10u SC qpm
• Hx of controlled HTN, stable angina
• How should this patient be managed?

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Case 1 cont.

• Preop
• Bowel prep and NPO at midnight
• Hold Metformin morning of OR
• Give 8u of NPH insulin am of OR
• Provide IV dextrose during OR
• Postop
• Hold metformin until eating well
• Give 16u of NPH qam and 10u of NPH qpm
• Continue IV dextrose until eating well
• Insulin sliding scale TID prn with meals

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Case examples

• Case 2
• Ms P, 36 yr old female with perforated DU
  awaiting in ER for urgent OR
• Type 1 DM for 15 yrs complicated by retinopathy,
  neuropathy, and gastroparesis
• On Levemir 20u BID and Novorapid sliding scale
  with meals by carb counting, average 4-6u per
  meal
• How should this patient be managed?

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Case 2 cont..

• Preop
• NPO, frequent glucoscans
• IV regular insulin starting at 2u/hr
• IV dextrose
• Postop
• Continue IV insulin and dextrose until eating
  well and overlap with SC insulin
• Watch for nausea and vomiting given hx of
  gastroparesis

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Take Home Message

• Common chronic health problem
• Needs to be managed closely perioperatively
• Associated with increased perioperative risk
• Not aiming for perfect glucose measurements but
  instead safe measurements