Diabetes Care, Vol 23, Issue 4 455-459, Copyright © 2000 by American Diabetes Association
Influence of caffeine on the frequency and perception of hypoglycemia in free-living patients with type 1 diabetes
JM Watson, EJ Jenkins, P Hamilton, MJ Lunt and D Kerr
Bournemouth Diabetes and Endocrine Centre, Royal Bournemouth Hospital, U.K.
OBJECTIVE: To examine the influence of caffeine on the frequency and
perception of hypoglycemia in "free-living" patients with type 1 diabetes.
RESEARCH DESIGN AND 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.