Caffeinated Energy Drinks May Spike Insulin Levels in Teens

Man opening an energy drink can
Man opening an energy drink can
Caffeinated energy drinks can cause dangerous fluctuations in blood glucose levels in adolescents.

A new study presented at the World Diabetes Congress suggests that consuming caffeinated energy drinks can cause blood insulin levels to spike and may lead to subsequent problems controlling blood glucose levels.

“Maintaining tight glucose control is important. This could be complicated by insulin resistance caused by energy drink consumption,” said study investigator Jane Shearer, PhD, who is an associate professor in the department of biochemistry and molecular biology at the University of Calgary in Canada.

Dr Shearer and colleagues found that consumption of a caffeine-containing energy drink may result in a 20% to 30% increase in insulin and glucose levels in response to a glucose load.

The researchers believe that since caffeine persists in the system for 4 to 6 hours after consumption, continuous insulin resistance associated with regular caffeine-containing energy drink consumption in adolescents could contribute to increased metabolic risk in susceptible individuals.

The caffeine-containing energy drink market has experienced exponential growth over the past 10 years, according to the researchers. Despite warning labels stating these drinks are not recommended for children, caffeine-containing energy drinks are aggressively marketed to, and increasingly consumed by, children, adolescents, and young adults. Around 30% of adolescents regularly consume these drinks, Dr Shearer noted, and as many as 50% of college-aged athletes report use.

While energy drinks contain a myriad of ingredients, the primary ingredient of concern for adolescents is caffeine. Children and adolescents are smaller compared with adults; therefore, they are much more likely to ingest higher amounts of caffeine per kg of body mass, according to the researchers.

In adults, co-administration of a carbohydrate load in the presence of caffeine has been shown to cause insulin resistance. However, relatively little is known about the metabolic impacts of these caffeinated beverages in teenagers who represent an understudied and potentially vulnerable population.

Dr Shearer and colleagues investigated the metabolic impacts of both caffeinated and decaffeinated energy drink consumption on insulin sensitivity and whole-body glucose disposal.

The study included 10 boys and 10 girls aged 13 to 19 years (mean age, 17 years). All the volunteers arrived at the laboratory in a fasting state and had abstained from caffeine and vigorous exercise for 24 hours.

Each participant underwent 2 double-blind, randomized trials in which they consumed either a common caffeinated energy drink (5 mg caffeine per kg) or an equivalent volume of a decaffeinated energy drink (containing only vitamins and minerals).

The brand of drink used was 5-Hour Energy Original and 5-Hour Energy Decaf. Consumption of the drink was followed 40 minutes later by a standard 2-hour oral glucose tolerance test (OGTT, 75 g). Both energy drinks were sugar-free. Blood samples were collected at –40 (baseline), 0 (initiation of OGTT), 30, 45, 60, 90, and 120 minutes.

The study revealed a 25% increase in blood glucose levels over the 2-hour measurement period following consumption of the caffeine-containing energy drink compared with the control (decaffeinated version). Elevations in glucose with the caffeine-containing energy drink were accompanied by significant increases in insulin levels (26%).

Dr Shearer noted that elevated glucose and insulin responses may contribute to increased metabolic risk, including type 2 diabetes and cardiovascular disease in susceptible individuals later in life. 

“The key messages are that kids, teens, or young adults should not consume these products. Warning labels need to state an age instead of ‘not for children,’ and parents need education,” Dr Shearer told Endocrinology Advisor. “Kids need education on caffeine and its effects. Marketing to kids should be limited.”

In the next trial, Dr Shearer’s team will be administering energy drinks to adolescents that contain both caffeine and glucose. Participants will be asked to drink 2 servings of large-format energy drinks per day or a control drink each day for 3 days. Their blood glucose levels will be continuously monitored over this period.

These studies are warranted in light of the growing incidence of type 2 diabetes in the United States and in Canada, according to Dr Shearer. Experts at the World Diabetes Congress reported that much greater public health efforts and more government regulation/rules are needed to help slow the wave of new cases of type 2 diabetes.


  1. Virtanen H, Johnsen V, Gougeon C, et al. Energy drink consumption impairs oral glucose tolerance in adolescents. Presented at the World Diabetes Congress; November 30-December 4, 2015; Vancouver, Canada.