You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Chemical"].

Please return the output as a JSON object of the format: {"Chemical": ["Arsenic", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

Gender and body mass index modify the effect of increasing amounts of caffeinated coffee on postprandial glucose and insulin concentrations; a randomized, controlled, clinical trial. OBJECTIVE: To examine the effects of different coffee amounts on blood glucose and insulin concentrations of healthy volunteers, and to assess potential effect modification by sex and body mass index category. MATERIALS/METHODS: Thirty-three volunteers [16♀/17♂, 16 normal-weight and 17 overweight/obese, 27.3±7.2 (19-44) y] took part in this randomized, crossover study. Ιn the morning of each experimental day volunteers received a standardized meal along with 200mL of water or instant coffee containing either 3 or 6mg of caffeine/kg body weight. Blood samples were obtained and analyzed for glucose and insulin concentrations in the fasting state, immediately after meal/drink consumption and at standard time points for the next 3h thereafter. RESULTS: Coffee delayed the rise of insulin in response to the standardized meal and the fall of glucose concentrations from its maximum levels in the entire study sample. Glucose incremental area under the curve (IAUC) was significantly different between interventions (P=.009) with both coffee amounts inducing a greater area compared to water. Secondary, subgroup analysis at the nominal level showed that this might be more evident among females (PIAUC=.05) and overweight/obese participants (PIAUC=.03). Furthermore, coffee, mainly the 6mg dose, could be lowering insulin concentrations the first 30min after its consumption compared to water in men and overweight/obese participants. CONCLUSIONS: Coffee exerts an acute effect on postprandial glucose and insulin concentrations. This effect may be modified by sex and overweight/obese status. Future research is necessary to elucidate underlying mechanisms.
{"Chemical": ["caffeine", "Glucose", "glucose"]}