Effects of Coffee Consumption on Metabolic Markers in Adults With Prediabetes and Obesity

Continuous glucose monitoring parameters,glucose from a 75 g-oral glucose tolerance test （mmol/L）,insulin from a 75 g-oral glucose tolerance test （pmol/L）,C-peptide from a 75 g-oral glucose tolerance test (ng/ml),glucagon from a 75 g-oral glucose tolerance test（pmol/L）,Glycated hemoglobin (HbA1c) ( % ),Fasting total cholesterol (mmol/L),Fasting high-density lipoprotein-cholesterol (mmol/L),Fasting low-density lipoprotein-cholesterol (mmol/L),Fasting triglycerides (mmol/L)

Epidemiological studies have shown an inverse association between coffee consumption and risk
 of type 2 diabetes. However, the randomized controlled trials in prediabetes are limited to
 evaluate the effects of coffee. The purpose of this study is to investigate the effects of
 coffee on metabolic factors and inflammation in individuals with prediabetes and obesity. A
 double-blind, randomized controlled trial is designed to explore the effects of coffee
 consumption on participants with prediabetes and obesity. A total of 100 eligible
 participants with prediabetes and obesity will be recruited from the Health Management Center
 of Nanjing First Hospital. These participants are randomly assigned in a 1:1 ratio to either
 the coffee capsule group or the control group. The coffee capsule group will be instructed to
 consume 3.6 g of coffee capsules per day (0.3 g per capsule, 6 capsules per serving, twice a
 day, once in the morning and once in the middle of the day). The control group will be asked
 to consume 3.6 g of cornstarch capsules (0.3 g per capsule, 6 capsules per serving, twice a
 day, once in the morning and once in the middle of the day). 75 g oral glucose tolerance
 test, 2-week blinded continuous glucose measurement and others will be performed before and
 after the 3-month intervention. During the three months of intervention, the information on
 dietary intake, physical activity and sleep of participants will be systematically collected.
 To comprehensively assess the impact of coffee intake on prediabetes and obesity, we will
 analyze the effects of coffee capsules on various metabolic and inflammatory markers,
 including glucose metabolism, lipid profiles, blood pressure, adiponectin, high sensitivity
 C-reactive protein, interleukin-6, body mass index, body composition, the degree of hepatic
 steatosis and so on. We will further adjust for potential confounding factors such as
 lifestyle factors to better understand the underlying biological mechanisms driving this
 association.