OBJECTIVE -Caffeine is a central stimulant that increases the release of catecholamines. As a component of popular beverages, caffeine is widely used around the world. Its pharmacological effects are predominantly due to adenosine receptor antagonism and include release of catecholamines. We hypothesized that caffeine reduces insulin sensitivity, either due to catecholamines and/or as a result of blocking adenosine-mediated stimulation of peripheral glucose uptake.RESEARCH DESIGN AND METHODS -Hyperinsulinemic-euglycemic glucose clamps were used to assess insulin sensitivity. Caffeine or placebo was administered intravenously to 12 healthy volunteers in a randomized, double-blind, crossover design. Measurements included plasma levels of insulin, catecholamines, free fatty acids (FFAs), and hemodynamic parameters. Insulin sensitivity was calculated as whole-body glucose uptake corrected for the insulin concentration. In a second study, the adenosine reuptake inhibitor dipyridamole was tested using an identical protocol in 10 healthy subjects.RESULTS -Caffeine decreased insulin sensitivity by 15% (P Ͻ 0.05 vs. placebo). After caffeine administration, plasma FFAs increased (P Ͻ 0.05) and remained higher than during placebo. Plasma epinephrine increased fivefold (P Ͻ 0.0005), and smaller increases were recorded in plasma norepinephrine (P Ͻ 0.02) and blood pressure (P Ͻ 0.001). Dipyridamole did not alter insulin sensitivity and only increased plasma norepinephrine (P Ͻ 0.01).CONCLUSIONS -Caffeine can decrease insulin sensitivity in healthy humans, possibly as a result of elevated plasma epinephrine levels. Because dipyridamole did not affect glucose uptake, peripheral adenosine receptor antagonism does not appear to contribute to this effect. Diabetes Care 25:364 -369, 2002C affeine is one of the most widely consumed "drugs" in the world. The average daily intake per capita in the western world is ϳ300 mg (1), and most of it comes from dietary sources such as coffee, tea, cola drinks, and chocolate. Caffeine is a methylxanthine derivative and a potent adenosine receptor antagonist that exerts its effects both centrally and peripherally because it crosses the blood-brain barrier. Systemic effects of caffeine include an increase in blood pressure and stimulation of the release of catecholamines, particularly epinephrine (2). Local effects of caffeine stem from interaction with interstitial adenosine (3).Data from animal studies have indicated that methylxanthines are involved in insulin-mediated glucose handling and insulin responsiveness in adipose and muscular tissue. In obese Zucker rats, the caffeine-related adenosine receptor antagonist 1,3 dipropyl-8-(acrylic) phenylxanthine was found to inhibit glucose uptake in adipose tissue, whereas the reverse was observed in skeletal muscle (4).Both effects were attributed to adenosine receptor antagonism at the tissue site because the compound does not cross the blood-brain barrier. Studies showing that adenosine or adenosine agonists increase insulin sensitivity in adipos...

Sensitivity to beta(2)-adrenergic receptor agonist stimulation is preserved in type 1 diabetic patients with hypoglycemia unawareness.

Aim: Most people with type 2 diabetes eventually require insulin treatment because of progressive loss of beta-cell function. The most common adverse effect of insulin therapy is hypoglycemia. Recurrent hypoglycemia may lead to impaired awareness of hypoglycemia (IAH) and a consequently high risk for severe hypoglycemia. The aim of this study was to determine the prevalence of IAH and severe hypoglycemia in a large cohort of people with insulin-treated type 2 diabetes. Methods: The Dutch Diabetes Pearl is a contemporary cohort of people with type 2 diabetes from primary, secondary and tertiary medical centers in the Netherlands. We collected data from people on insulin therapy who had completed the validated Dutch version of the Clarke questionnaire on IAH, where 3 out of 5 points indicate IAH. Descriptive statistics, T-tests and Chi-square tests were performed. Results: Our study included 1923 patients of whom 59% were men. Median age was 62.1 years (interquartile range 55.1-68.3), median diabetes duration was 13.9 years (8.8-20.1) and median HbA1c was 7.6 % (7.0-8.5). 2individuals (10.8%) were classified as having IAH; these people were more likely to be non-Caucasian and have a lower educational level, and less likely to have a partner. Severe hypoglycemia was reported in 617 patients (32.1%) and severe hypoglycemia requiring medical intervention in the past year in 166 patients (8.6%). People with severe hypoglycemia were more likely to be non-Caucasian, to have a lower educational level, to have a history of cardiovascular events and neuropathic pain, and to use over 10 different types of drugs. No significant associations between HbA1c-levels and IAH or severe hypoglycemia were observed. Conclusion: IAH and severe hypoglycemia are common in people with type 2 diabetes treated with insulin. Non- Caucasian ethnicity, lower educational level, and being single may be risk factors for IAH in patients with type 2 diabetes. Disclosure L. van Meijel: None. F. de Vegt: None. C. Tack: Advisory Panel; Self; Merck Sharp & Dohme Corp., Novo Nordisk A/S, AstraZeneca. Research Support; Self; AstraZeneca. Speaker's Bureau; Self; Novo Nordisk A/S. E.J. Abbink: None. F. Rutters: None. J.M. Dekker: None. B.H. Wolffenbuttel: None. F. Holleman: Other Relationship; Self; Sanofi-Aventis, Bioton, AstraZeneca. J. DeVries: Research Support; Self; Dexcom, Inc., Medtronic, Novo Nordisk A/S. Advisory Panel; Self; Novo Nordisk A/S. Speaker's Bureau; Self; Novo Nordisk A/S, Roche Diabetes Care Health and Digital Solutions. Advisory Panel; Self; Sanofi. Research Support; Self; Senseonics. Speaker's Bureau; Self; Senseonics. Advisory Panel; Self; Zealand Pharma A/S. N. Masurel: None. H. Pijl: None. B. Ozcan: None. B. Silvius: None. B.E. de Galan: Research Support; Self; AstraZeneca, Sanofi. Advisory Panel; Self; Novo Nordisk A/S.

Background: Insulin-induced hypoglycemia, the most common adverse event in people with diabetes treated with insulin, is associated with increased risk of cardiovascular events. The effect of hypoglycemia on cardiac function has not yet been fully clarified. Our aim was to investigate the effect of hypoglycemia on left ventricular ejection fraction (LVEF) and global longitudinal strain (GLS) in people with type 1 diabetes (T1DM) and in healthy controls (HC). Methods: We enrolled 15 adults with T1DM (M/F 9/6, age 47±19 years, HbA1c 7.9±2.9%, diabetes duration 22.5±12.6 years) and 14 HCs (M/F 7/7, age 39±17 years). All participants underwent a hyperinsulinemic normoglycemic (5.3±0.4 mmol/L, 30 min) hypoglycemic (2.8±0.5 mmol/L, 60 min) glucose clamp. At baseline and approximately 30 min into the hypoglycemic phase (steady-state), a cardiac ultrasound was performed (by the same person), for later analysis. Results: All participants had sinus rhythm at baseline and none developed arrhythmias during hypoglycemia. We found no difference between T1DM and HC for LVEF measured at baseline. In response to hypoglycemia, LVEF increased from 58.1±2.6% at baseline to 63.7±4.0% in the T1DM group (p<0.0005) and from 58.0±3.8% to 64.7±2.4%, (p<0.005) in the HC group. GLS was unchanged (-20.9±1.5% to -21.3±3.5% (p=0.800)) in the T1DM group, but a numerical decrease from -19.6±3.0% to -22.0±2.7% (p=0.084) was seen in the HC. Age did not modulate the effect of hypoglycemia on LVEF or GLS. Conclusion: An event of hypoglycemia increases the LVEF significantly in people with diabetes. Presumably due to the catecholamines chronotropic, inotropic and peripheral contracting effect. The result of this would be increased cardiac output, increased oxygen consumption and metabolism and thereby increased load on the heart. This may contribute to explain the link between hypoglycemia and cardiovascular disease. Disclosure T. W. Fabricius: None. C. E. Verhulst: None. M. Wienberg: None. A. L. Duijnhouwer: None. P. L. Kristensen: Speaker’s Bureau; Self; AstraZeneca, Eli Lilly and Company. B. E. De galan: Research Support; Self; Novo Nordisk. U. Pedersen-bjergaard: Advisory Panel; Self; Novo Nordisk A/S, Sanofi-Aventis, Consultant; Self; Abbott, Speaker’s Bureau; Self; Novo Nordisk A/S. Funding Innovative Medicines Initiative 2 Joint Undertaking (777460); European Union Horizon 2020 Research and Innovation Program; European Federation of Pharmaceutical Industries and Associations; T1D Exchange; JDRF; International Diabetes Federation; The Leona M. and Harry B. Helmsley Charitable Trust