title: Do high fasting glucose levels suggest nocturnal hypoglycaemia? The Somogyi effect-more fiction than fact?
abstract: OBJECTIVE
  The Somogyi effect postulates that nocturnal hypoglycaemia causes fasting hyperglycaemia attributable to counter-regulatory hormone release. Although most published evidence has failed to support this hypothesis, this concept remains firmly embedded in clinical practice and often prevents patients and professionals from optimizing overnight insulin. Previous observational data found lower fasting glucose was associated with nocturnal hypoglycaemia, but did not assess the probability of infrequent individual episodes of rebound hypoglycaemia. We analysed continuous glucose monitoring data to explore its prevalence.
  
  
  METHODS
  We analysed data from 89 patients with Type 1 diabetes who participated in the UK Hypoglycaemia study. We compared fasting capillary glucose following nights with and without nocturnal hypoglycaemia (sensor glucose < 3.5 mmol/l).
  
  
  RESULTS
  Fasting capillary blood glucose was lower after nights with hypoglycaemia than without [5.5 (3.0) vs. 14.5 (4.5) mmol/l, P < 0.0001], and was lower on nights with more severe nocturnal hypoglycaemia [5.5 (3.0) vs. 8.2 (2.3) mmol/l; P = 0.018 on nights with nadir sensor glucose of < 2.2 mmol/l vs. 3.5 mmol/l]. There were only two instances of fasting capillary blood glucose > 10 mmol/l after nocturnal hypoglycaemia, both after likely treatment of the episode. When fasting capillary blood glucose is < 5 mmol/l, there was evidence of nocturnal hypoglycaemia on 94% of nights.
  
  
  CONCLUSIONS
  Our data indicate that, in clinical practice, the Somogyi effect is rare. Fasting capillary blood glucose ≤ 5 mmol/l appears an important indicator of preceding silent nocturnal hypoglycaemia.
authors.affiliation: Academic Unit of Diabetes, Endocrinology and Metabolism, University of Sheffield, Sheffield, UK. pratik.choudhary@kcl.ac.uk
authors.forename: P
authors.initials: P
authors.lastname: Choudhary
authors.forename: C
authors.initials: C
authors.lastname: Davies
authors.forename: C J
authors.initials: CJ
authors.lastname: Emery
authors.forename: S R
authors.initials: SR
authors.lastname: Heller
mesh_terms: D000328:Adult; D061265:Biphasic Insulins / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use; D001786:Blood Glucose / Q000032:analysis*; D015190:Blood Glucose Self-Monitoring; D002940:Circadian Rhythm; D015331:Cohort Studies; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000188:drug therapy*; D016903:Drug Monitoring; D006801:Humans; D006943:Hyperglycemia / Q000139:chemically induced / Q000453:epidemiology; D007003:Hypoglycemia / Q000139:chemically induced* / Q000453:epidemiology / Q000503:physiopathology; D007004:Hypoglycemic Agents / Q000008:administration & dosage / Q000009:adverse effects* / Q000627:therapeutic use; D007328:Insulin / Q000008:administration & dosage / Q000009:adverse effects* / Q000627:therapeutic use; D000069036:Insulin Glargine; D007336:Insulin, Isophane / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use; D049528:Insulin, Long-Acting / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use; D008875:Middle Aged; D018670:Monitoring, Ambulatory; D015995:Prevalence; D012720:Severity of Illness Index; D006113:United Kingdom / Q000453:epidemiology
chemical_list: D061265:Biphasic Insulins; D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin; D049528:Insulin, Long-Acting; D000069036:Insulin Glargine; D007336:Insulin, Isophane