glycemic control

Introduction

Control of blood glucose. Also see dysglycemia.

Benefit/risk

• tight glycemic control (blood glucose 72-135 mg/dL)
  • time-to-benefit ~10 years to reduce microvascular complications
  • no benefit immediately after ischemic stroke
  • number needed to harm = 7 hypoglycemia
• tight glycemic control HgbA1c = 6.5-7.0% for 5 years for type 2 diabetes
  • no benefit for reducing risk of stroke, MI, renal failure or death
  • number needed to treat (NNT) to prevent 1 limb amputation = 250
  • number needed to harm = 6 (hospitalization for severe hypoglycemia)
• tight glycemic control < HgbA1c of 6.5% not associated with lower risks for retinopathy or microalbuminuria, but does increase risk for hypoglycemia
• tight glycemic control risky in cognitively impaired nursing home residents
• both hypoglycemia & hyperglycemia associated with cognitive impairment

* also see management

Laboratory

• screening for dysglycemia
  • oral glucose tolerance test is superior to hemoglobin A1c (HbA1c) for detecting dysglycemia in patients with coronary artery disease
  • strongest predictors of cardiovascular outcomes are 2-hour post-load glucose levels >= 9 mmol/L & HbA1c >= 5.9%
• hemoglobin A1c & blood glucose for monitoring patients with diabetes mellitus

Management

General

• avoiding episodes of hypoglycemia assume highest priority
• self glucose monitoring not recommended for patients with type 2 diabetes not on insulin or other drug associated with hypoglycemia
• outpatients with type 2 diabetes on QHS glargine or other long-acting insulin
  • target morning preprandial glucose < 150 mg/dL
• hemoglobin A1c targets:
  • < 7% healthy young adults
  • < 7.5% healthy older adults
  • < 8% older adults with with multiple chronic illnesses

hospitalized, non-critical care patients

• all patients serum glucose on admission
• hemoglobin A1c levels if not measured within 2-3 months (diabetics)
• point-of-care blood glucose testing
  • enteral or parenteral nutrition or glucocorticoids
    • before meals & QHS
    • every 4-6 hours if NPO or continuous enteral feeding
  • in patients without diabetes, discontinue testing when blood glucose <140 mg/dL without insulin for at least 24-48 hours
• insulin parenteral including basal & preprandial insulin
• discontinue oral hypoglycemic medications in hospitalized patients
• avoid hypoglycemia
• target blood glucose for hospitalized patients with diabetes mellitus is 140-200 mg/dL
• tight glycemic control (80-110 mg/dL) may increase mortality
• nutrition consult for all patients with hyperglycemia
• all diabetics treated with insulin as outpatient should receive scheduled subcutaneous insulin in the hospital
• avoid sole &/or prolonged use of insulin sliding-scale
• transition all diabetic patients to subcutaneous insulin at least 1-2 hours before discontinuation of intravenous insulin infusion
• all surgical patients with diabetes mellitus type 1 & most with diabetes mellitus type 2 should receive subcutaneous insulin or insulin infusion to prevent hyperglycemia
• at hospital discharge, provide patients, family, & caregivers with easy-to-understand written & oral instructions
• an inpatient virtual glucose management service (uses EMR) may improve glycemic control & prevent some episodes of hypoglycemia

=

• insulin infusion may be preferred
• intensive glycemic control not recommended
  • reduced mortality (15% vs 21%)*;
  • increased mortality (25% vs 27%);
  • no benefit in mortality;
  • no benefit in pediatric patients after cardiac surgery
  • reduced new cases of renal failure (3 vs 12), or need for renal replacement therapy
  • reduced need for blood transfusion (excluding GI bleed) (21% vs 25%)
  • shortened median ICU stay (1.6 vs 1.9 days); no differencs in median ICU stay
  • beneficial for ICU stays > 3 days, but may be harmful for short ICU stays < 3 days (reason unclear)
  • no difference in days of mechanical ventilation
  • increased incidence of hypoglycemia
    • incidence of severe hypoglycemia < 1%
• goal for blood glucose is 140-200 mg/dL; 140-180 mg/dL
  • ACP guidelines
  • no mortality benefit for targeting lower levels
• hypoglycemia associated with increased mortality
• tight glycemic control not indicated in pediatric patients
  • hypoglycemia associated with increased mortality
  • non-cardiac surgery patients
    • less likely to become hypoglycemic
    • may have lower costs & shorter hospital stays with tight glycemic control
    • tight glycemic control does not improve mortality
• ICUs slow to adapt to recommendations against tight glycemic control in the ICU
• tight glycemic control 80-110 mg/dL of no benefit in critically ill children
• critically ill diabetic patients not harmed by glucose targets of 180-250 mg/dL

* Re-evaluation suggests hyperglycemia a risk factor for ICU mortality only in previously unrecognized diabetics

Notes

Continuous glucose monitoring may be useful for resolving inconsistencies in plasma glucose & hemoglobin A1c

Postprandial plasma glucose may be useful for

• preprandial plasma glucose - HgbA1c discrepancies
  • preprandial plasma glucose at target, but HgbA1c not at goal
  • preprandial plasma glucose at not at target, but HgbA1c at goal
• measure post postprandial glucose to adjust mealtime insulin rather than increase long-acting insulin

Patients undergoing CABG (& presumably other surgery)

• tight glycemic control (serum glucose 90-120 mg/dL) increases the incidence of hypoglycemic events & does not result in any significant improvement in clinical outcomes relative to moderate glycemic control (serum glucose 120-180 mg/dL)

no relation between perioperative mortality & HbA1c

intensive glycemic control in patients with type 1 diabetes may not be apparent in patients with type 2 diabetes

• intensive glycemic control reduces need for eye surgery in patients with type 1 diabetes

No benefit for intensive glucose control in patients with long-standing diabetes mellitus type 2 (see VADT trial), & ACCORD trial

• no benefit in preventing cardiovascular events
  • fewer non-fatal acute coronary events despite higher cardiovascular & all-cause mortality
  • higher mortality with intensive glycemic control seen primarily in patients with chronic kidney disease
• no benefit in preventing microvascular complications (diabetic nephropathy, diabetic retinopathy ..)
• no benefit in preventing diabetic nephropathy
• no benefit in life expectancy
• no benefit in quality of life

Meta-analysis of 13 trials fails to show benefit of intensive glycemic control, finds reduction in non-fatal MI (HR-0.85) & microalbuminuria (HR-0.90) with intensive glucose control, but not stroke, congestive heart failure, diabetic retinopathy, peripheral vascular disease or mortality

6 years of intensive glycemic control in veterans with long-standing type 2 diabetes is not associated with cardiovascular benefit, but after an additional 4 years of standard glycemic control, cardiovascular events were reduced 0.86% in the intensive glycemic control group (NNT to prevent 1 cardiovascular event = 116); no mortality benefit

Intensive glycemic control (Hgb A1c < 6.5%) in patients with type 2 diabetes lowers risk of end-stage renal disease (ESRD)

• number needed to treat to prevent one case of ESRD = 430

Intensive glycemic control is common among elderly with type 2 diabetes is common & associated with increased risk of hypoglycemia

better glycemic control, even within the normal range, is correlated with better memory & hippocampal structure in the elderly

A low glycemic diet supplemented with canola oil is associated with slightly better glycemic control that a diet rich in whole grains in patients with diabetes mellitus type 2

fasting until noon associated with higher blood glucose after lunch & dinner in patients with type 2 diabetes

white wine (150 mL daily) associated with reduced fasting plasma glucose (17.2 mg/dL) in patients with type 2 diabetes

• only slow ethanol metabolizers benefit

extra virgin olive oil

• lowers post-prandial serum glucose & LDL cholesterol
• no change in serum glucose or lipid profile

brief interruptions of prolonged sitting with standing or light exercise improves postprandial glycemic control in prediabetic postmenopausal women

gut microbiome influences glycemic control

indoor light environment modulates postprandial substrate handling, energy expenditure & thermoregulation of insulin-resistant diabetics in a time-of-day-dependent manner

• evening plasma glucose pre- & post-prandial lower by ~ 5 mg/dL after exposure to bright light during the daytime

a text message based, self management support program may result in modest improvements in glycemic control in adults with poorly controlled diabetes

More specific terms

• impaired glycemic control

Additional terms

• continuous glucose monitor (Dexcom G5 CGM; G4 Platinum CGM System with Dexcom Share system, Flash glucose monitoring system, Eversense)
• diabetes mellitus
• glucose in serum/plasma
• glucose monitor
• hemoglobin A1c in red blood cells (Tina-quant HbA1cDx)
• hyperglycemia
• hypoglycemia