title: Influence of caffeine on the frequency and perception of hypoglycemia in free-living patients with type 1 diabetes.
abstract: OBJECTIVE
  To examine the influence of caffeine on the frequency and perception of hypoglycemia in "free-living" patients with type 1 diabetes.
  
  
  METHODS
  A total of 34 patients with type 1 diabetes were recruited for a prospective randomized placebo-controlled double-blind study. After a lead-in phase and while adhering to a low-caffeine diet, subjects were randomized to capsules containing either 200 mg caffeine or matched placebo with crossover at 3 months. Hypoglycemic episodes were monitored throughout with capillary blood glucose readings and a symptom questionnaire. During the study, measurements of blood pressure, middle cerebral artery blood velocity (a surrogate measure of cerebral blood flow), cognitive function (via a four-choice reaction time test), HbAlc levels, and lipid profiles were taken at the beginning and end of each phase.
  
  
  RESULTS
  Throughout the study, no changes were evident regarding glycemic control or lipid profile. The number of symptomatic episodes was greater with caffeine (1.3 vs. 0.9 episodes/week; P < 0.03) and was associated with more intense warning symptoms (29 vs. 26 total symptom score; P < 0.05). For women, caffeine ingestion caused a modest pressor response (115 vs. 110 mmHg; P < 0.01). Four-choice reaction time improved slightly with caffeine supplementation (P < 0.05).
  
  
  CONCLUSIONS
  Ingestion of modest amounts of caffeine enhances the intensity of hypoglycemia warning symptoms in patients with type 1 diabetes without altering the prevailing standard of glycemic control or increasing the incidence of severe hypoglycemic episodes.
authors.affiliation: Bournemouth Diabetes and Endocrine Centre, Royal Bournemouth Hospital, U.K.
authors.forename: J M
authors.initials: JM
authors.lastname: Watson
authors.forename: E J
authors.initials: EJ
authors.lastname: Jenkins
authors.forename: P
authors.initials: P
authors.lastname: Hamilton
authors.forename: M J
authors.initials: MJ
authors.lastname: Lunt
authors.forename: D
authors.initials: D
authors.lastname: Kerr
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000032:analysis; D001794:Blood Pressure / Q000187:drug effects; D002110:Caffeine / Q000494:pharmacology*; D002560:Cerebrovascular Circulation; D003071:Cognition / Q000187:drug effects; D018592:Cross-Over Studies; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000503:physiopathology*; D004311:Double-Blind Method; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007003:Hypoglycemia / Q000453:epidemiology* / Q000503:physiopathology* / Q000523:psychology; D008297:Male; D010465:Perception / Q000187:drug effects*; D010919:Placebos; D012727:Sex Characteristics; D011795:Surveys and Questionnaires
chemical_list: D001786:Blood Glucose; D010919:Placebos; D002110:Caffeine