Insulin, primarily known to the medical community as the mainstay of therapy for type 1 diabetes mellitus and used commonly in the treatment of type 2 and gestational diabetes mellitus, has a different reputation in the gyms and fitness centers around the world (1,5,15,20). Owing to its ability to cause weight gain via its anabolic properties on both muscle and fat, insulin represents an attractive option for strength-trained individuals who are interested in “bulking up” (13,21).
Prior literature has documented that 5.3% to 25% of anabolic-androgenic steroid (AAS) users in the past decade have incorporated insulin into their workout routine (2,4,10,11,16,18). However, none of these studies detailed insulin misuse. The study at hand includes 41 nondiabetic insulin users and represents the largest case series focusing on insulin use among strength-trained individuals in the literature. The authors hope to alert the medical, research, and fitness communities about insulin misuse. Owing to insulin’s high-risk potential and relatively easy access as an over-the-counter medication in the United States, this misuse would seem to present a real and substantial concern. The purpose of this study was to analyze the current trends in insulin use in the strength training community.
Study Design and Population
A 99-item Web-based survey, the Anabolic 500, was administered via SurveyMonkey (Palo Alto, CA) to assess characteristics of strength-trained individuals (11). The current subanalysis of the Anabolic 500 details the demographic data of individuals using insulin for performance enhancement and describes their utilization and acquisition of insulin. Regarding utilization, types of insulin, dosing, route, timing, and frequency of insulin administrations were assessed. Subjects also were asked if they used a blood glucose meter and if they have ever experienced or were concerned about adverse effects of insulin (e.g., hypoglycemia or unconsciousness). Symptoms consistent of hypoglycemia were presented for the subjects as a blood glucose reading less than 70 mg·dL−1 or symptoms of shakiness, sweating, dizziness, rapid heart rate, or irritability after insulin use. Subjects also were questioned about their insulin and syringe acquisition.
Subjects were eligible to participate in the survey if they had Internet access, participated in regular strength training exercise, and agreed to complete the survey. Inclusion criteria for the current analysis included specifically self-reported insulin users; a comparison of AAS users and nonusers has been described previously (11). Non-insulin users and insulin users with a diagnosis of diabetes mellitus were excluded from the analysis. Data from incomplete surveys, from surveys with hoax or illogical responses, and from surveys filled out too rapidly (<5 min for a self-reported AAS user and <3 min for a nonuser of AAS) were also excluded. A pilot test of 15 strength-trained individuals demonstrated that the average AAS user and nonuser spent roughly 30 and 10 min, respectively, to complete the survey.
Data Collection and Security
Participants were recruited from 38 Internet discussion boards of various fitness, bodybuilding, weightlifting, and anabolic steroid Web sites between February 19 and June 30, 2009. The Touro 12-Step, a step-by-step approach for optimizing discussion boards for online research, was used to increase survey visibility and participation (12). A survey Web link directed potential subjects to an informed consent page providing additional information regarding the study and assuring confidentiality and anonymity. No individually identifiable data were collected, Internet provider addresses were not logged, and data transfer was encrypted. Only researchers identified in this institutional review board proposal had access to the data, and all researchers completed previously the National Institutes of Health Human Subjects training. The study received institutional review board approval from Touro University (application no. P-0308).
All statistical analyses were conducted using SAS for Windows version 9.1 (SAS Institute, Cary, NC). As the survey was primarily descriptive in nature, means and standard deviations have been reported for continuous data, and frequency and percentages have been reported for categorical data.
When the survey closed on June 30, 2009, there were 2,380 survey attempts. Of these, 861 were excluded for the following reasons: not completing the survey to its entirety (n = 842), reporting hoax/illogical responses or completing the survey too rapidly (n = 10), and not being involved in strength training (n = 9). These exclusions left 1,519 strength-trained subjects who completed and submitted a valid survey during the study time frame. Among the 1,519 subjects, 518 were self-reported AAS users (current or prior AAS users) and 1,001 were non-AAS users (no history of AAS use). There were a total of 43 insulin users. Of the 43 insulin users, 2 were excluded for having a diagnosis of diabetes mellitus, leaving a final analytical cohort of 41 nondiabetic insulin users.
The demographic data describing the insulin users are summarized in Table. Among the 41 insulin users, 40 (97.6%) were male. The average insulin user was 30.7 ± 9.2 years of age, weighed 100.6 ± 11.0 kg, and had a body mass index of 31.6 ± 3.4 kg·m−2. Most users were currently seeking to gain body weight (68.4%), while 28.2% were trying to maintain weight and 7.9% were trying to lose weight. Most were Caucasian/white (86.8%) and heterosexual (97.4%), while 36.8% were single and 31.6% were married. When asked about the highest level of education completed, 45.0% had obtained a bachelor’s degree or higher. The insulin users strength-trained 4.6 ± 1.0 d for a total of 6.3 ± 3.6 h·wk−1. Most saw their primary care physician regularly (79.0%), but only 8.1% believed that physicians were knowledgeable about AAS or performance-enhancing drugs (PEDs).
The subjects were asked to classify themselves as either a recreational exerciser, a competitive bodybuilder, a competitive powerlifter/Olympic-style weightlifter, or a competitive athlete. Recreational exerciser (47.5%) was the most commonly reported self-classification followed by competitive bodybuilder (35.0%), competitive athlete (10.0%), and competitive powerlifter/Olympic-style weightlifter (7.5%).
AAS and PEDs Utilization
The typical insulin user incorporated 16.2 ± 5.6 total PEDs in his or her routine during a 1-year period. Most insulin users (95.1%) also used AAS. Other agents that were frequently used included creatine (85.0%), protein powder (82.5%), multivitamin (72.5%), tamoxifen (67.5%), clomiphene (62.5%), clenbuterol (60.0%), caffeine (60.0%), ephedrine (60.0%), amino acids (57.5%), human chorionic gonadotropin (55.0%), anastrazole (52.5%), and human growth hormone (47.5%). The mean yearly expenditure on PEDs was U.S. $2,247.30 ± 2,045.79.
Most insulin users used short-acting (regular insulin) or rapid-acting insulins (aspart or lispro). Lispro (51.2%) was the most commonly used insulin followed by regular insulin (36.6%) and then aspart (4.9%). No subjects used glargine (a long-acting insulin), and only one subject used NPH insulin (an intermediate-acting insulin). Lispro, regular insulin, and aspart were administered at 7.0 ± 4.2, 11.5 ± 6.8, and 7.0 ± 4.2 U per dose, respectively. Insulin was most frequently dosed once per day (61.0%) and was most often administered only before a postworkout meal (54.3%). No subjects administered their insulin after a meal or at bedtime.
The most common site and technique of the insulin administration was subcutaneously in the abdomen (56.1%) followed by intramuscularly in the arm/deltoid (29.3%). Internet Web site discussion boards (44.1%), Internet Web site articles (35.3%), local sources (friends, training partner, gym member/dealer) (23.5%), and health care professionals (20.6%) were the most likely sources for determining insulin dosing. Most insulin users (64.9%) did not use a blood glucose meter when using insulin.
Adverse Physical Effects of Insulin
Hypoglycemia was reported by most insulin users (56.8%). One subject (2.9%) also reported becoming unconscious as a result of insulin-induced hypoglycemia. Most users were concerned about possible adverse effects of insulin (56.8%).
Insulin and Syringe Acquisition
Insulins were most commonly obtained from local sources (friends, training partners, gym member/dealer; 40.5%) and community pharmacies (37.8%) followed by Internet-registered pharmacies (13.5%) and Internet suppliers (8.1%). Regarding difficulty (easy, moderate, or difficult) in obtaining their insulin, 80.6% found it easy, 16.7% found it moderate, and only 2.8% found it difficult.
Insulin syringes were most commonly obtained from community pharmacies (47.1%) and Internet suppliers (35.3%) followed by local sources (17.6%) and needle exchange programs (5.9%). Regarding difficulty in obtaining their insulin syringes, 90.9% found it easy, 9.1% found it moderate, and no one found it difficult.
The trend in insulin misuse over the past two decades is summarized in the Figure. In a 1992 survey by Perry et al. (17), no mention of insulin use was reported among British AAS users. In 1997, Evans (7) revealed that 2% of British AAS users used insulin. Since then, insulin utilization among AAS users has increased and peaked to a high of 25% in 2004 (2,4,10,11,16,18). The current study confirms the presence of insulin misuse among AAS users (39/518, 7.5%). Insulin may have decreased in popularity perhaps because of the high-risk nature of insulin compared with other anabolic agents. Regardless, its continued use remains prevalent.
The most common insulins being used are rapid- and short-acting insulins, which have a faster onset and shorter duration of action than basal insulins (NPH, detemir, glargine). Insulins with shorter durations are likely being used to prevent hypoglycemia. Despite this, it is concerning that most insulin users report potentially experiencing hypoglycemia, and one user in the current study reported an episode of unconsciousness secondary to insulin-induced hypoglycemia.
In addition, three case reports in the literature have described insulin-induced hypoglycemia among insulin misusers resulting in unconsciousness (6,8,19). Elkin et al. (6) illustrated a 21-year-old male AAS-using bodybuilder who experienced severe brain damage after administering excessive insulin. Reverter et al. (19) reported a 19-year-old male AAS-using bodybuilder who was admitted to the emergency department after experiencing generalized convulsions due to hypoglycemia after administering 320 U of regular insulin. Evans and Lynch (8) reported a 31-year-old AAS-using male who presented to the emergency department after being found unconscious at his home.
Regarding acquisition, it is disturbing that most insulin misusers find it “easy” to obtain their insulin and insulin syringes. Local sources (e.g., friends, training partners, gym member/dealer) and community pharmacies are the top two sources where insulin is acquired. As such, fitness trainers or gym owners who are more likely to encounter these individuals on a more frequent basis may be potential targets of education and intervention. In U.S. pharmacies, various insulins such as regular insulin and NPH are available as over-the-counter products and can be purchased “behind-the-counter” without a prescription in multiple states (9). This also may be contributing to the lack of difficulty in obtaining insulin. By increasing awareness, pharmacists may potentially educate individuals misusing insulin. Lastly, physicians should be aware that a percentage of patients using AAS also use insulin and that many of these individuals visit their primary care physicians regularly. Continuing medical education programs may be ideal venues to promote awareness to physicians and pharmacists.
There are limitations to our research, which must be considered. First, surveys, by nature, lead to information bias based on the participant’s recall of experiences. Second, the Internet was used for all subject recruitment and survey administration. Using an Internet-based survey results in a potential selection bias, and the results may not be generalizable to all populations. However, the Internet provides a broader and geographically diverse population than traditional surveys (i.e., paper-and-pencil or telephone survey), and various sources have demonstrated the reliability and validity of Internet-based data collection for research when compared with traditional methods (3,14).
Insulin misuse remains prevalent in the strength training community, particularly among AAS users. It is worrisome that insulin misusers obtain their insulin and syringe supply from local sources (e.g., friends, training partners, gym member/dealer) and community pharmacies with relative ease, administer insulin without measuring their blood glucose levels, and have reported episodes of hypoglycemia and even unconsciousness. Because of the potential and sometimes severe complications of insulin misuse, the medical, research, and fitness communities should be made aware of the trends in abuse and encourage education among those at risk.
The authors declare no conflict of interest and do not have any financial disclosures.
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