Prediabetes is a remarkably common health problem that has been vastly underdiagnosed. The Centers for Disease Control and Prevention (CDC) estimate that 38% of the adult population in the United States has prediabetes, with 48.8% of adults 65 years of age and older having blood glucose values that meet the criteria [3]. About one in five adolescents and one in four young adults (19 to 34 years of age) in the United States has prediabetes [4]. In spite of the high prevalence of prediabetes, only 19% of people with this condition are told of their diagnosis [3].

Although it is underdiagnosed, prediabetes is a serious condition that significantly increases the risk for major health problems. People with prediabetes are approximately 5 to 15 times more likely to develop diabetes than those who have normal blood glucose levels [5]. Furthermore, the harmful effects of high blood glucose begin to occur at much lower levels than currently define diabetes. In other words, complications of diabetes begin early in the course of glucose intolerance, often before diabetes is diagnosed. Studies suggest that when blood glucose is higher than normal and remains untreated, patients have a greater risk for developing the microvascular and macrovascular complications associated with diabetes [6,7,8]. For example, characteristics of diabetic retinopathy may be detected in people with no history of diabetes who have elevated fasting blood glucose or impaired glucose tolerance (IGT) [9]. Impaired glucose tolerance is also common in nondiabetic patients with peripheral neuropathy [10]. This data emphasize the importance of prompt detection and intervention of prediabetes. In fact, research suggests that restoring blood glucose levels to normal, rather than maintaining prediabetic levels, is necessary to prevent complications [7,8]. When preventive efforts delay the onset of diabetes, there is less disease exposure and lower risk for the adverse consequences of high blood glucose over time. This results in better quality of life for the individual and lower healthcare costs for society.

There are many tests available to assess patients suspected of having diabetes or prediabetes. These include [13]:

There are many tests available to assess patients suspected of having diabetes or prediabetes. These include [13]:

A diagnosis of diabetes is established when a person has any or all of the following blood glucose values [13]:

Evidence suggests that the microvascular damage from high blood glucose begins early in the progression from normal glucose tolerance to frank diabetes. Studies of people with prediabetes indicate that risk for retinopathy, nephropathy, and neuropathy are all increased [6]. Retinal microaneurysms and microalbuminuria, the hallmarks of diabetic retinopathy and nephropathy respectively, have been detected in a significant number of nondiabetic people with IGT [9]. IGT is common in patients with peripheral neuropathy, and a causal relationship has been assumed, though not adequately studied. The risk for retinopathy and nephropathy may begin to increase when two-hour postprandial blood glucose levels reach 162 mg/dL [10].

Risk factors for diabetes and prediabetes include [6]:

Insulin resistance, or the impairment of the body to effectively utilize available insulin, is the hallmark of both metabolic syndrome and type 2 diabetes. In people with early stage type 2 diabetes, insulin resistance reduces glucose uptake by 35% to 40%. With insulin resistance, the pancreas may produce normal or greater than normal amounts of insulin, but receptor sites for it are not available. For some people, the pancreas is temporarily able to make enough additional insulin to overcome the insulin resistance and produce normal blood glucose levels. Hyperinsulinemia is usually the case in early stages of type 2 diabetes and is associated with macrovascular risk factors of the metabolic syndrome, such as dyslipidemia and hypertension. High levels of insulin in the blood increase sympathetic activity that can raise blood pressure.

The chronic complications of diabetes have an immense effect on the healthcare system, society, and the individual. While the economic costs of diabetic complications are enormous, their affect upon quality of life for the individual and family can be equally devastating. The CDC reports the impact of chronic complications upon Americans with diabetes as [3]:

The DPP was a landmark study on the prevention of diabetes. The results, published in the New England Journal of Medicine in 2002, reported that diabetes could be prevented or delayed in people with IFG and IGT [2]. Using subjects with prediabetes who were overweight, the study compared the results of treatment with the diabetes medication metformin versus lifestyle changes that led to weight loss. Importantly, the DPP showed that the greatest reduction in diabetes risk was associated with lifestyle changes that resulted in a 5% to 7% loss of body weight. Ten-year follow-up of DPP subjects has shown that diet and exercise, resulting in weight loss, could keep diabetes at bay for at least a decade in those at high risk [34].

The results of the DPP also showed that diabetes could be prevented with the use of metformin in people with prediabetes, with risk reduction of about 31% [35]. Risk reduction with use of metformin was found to be most effective for people 25 to 44 years of age and in those who had a body mass index of 35 or higher [35]. After 10 years, the incidence of type 2 diabetes was decreased by 18% in the metformin group as compared to placebo [34].

General evidence-based dietary guidelines for the prevention and treatment of diabetes are to:

Reducing calories and increasing physical activity are the cornerstones of healthy weight loss [51]. Successful weight management to improve overall health requires a lifelong commitment to a healthful lifestyle that emphasizes sustainable and enjoyable eating practices and daily physical activity [49,51]. For safe weight loss, the Academy of Nutrition and Dietetics and the ADA recommend a reduction of 500 to 1,000 calories per day to achieve a target weight-loss rate of 1 to 2 pounds per week [51].

Excess waist circumference with associated health risk is identified as greater than 40 inches in men or greater than 35 inches in nonpregnant women [57]. The proper way to measure abdominal circumference is to place a tape measure around the bare abdomen, just above the hipbone. The tape should be parallel to the floor and snug, but not compressing the skin. Instruct the patient to exhale and relax for the measurement [57].

Studies indicate that portion control is a valid component of a healthy and effective weight loss plan. Based on these studies, the Academy of Nutrition and Dietetics recommends that portion control be integrated into the weight-loss plan. To help patients with portion control, advise them to [61]:

The Academy of Nutrition and Dietetics recommends that for weight loss and maintenance a registered dietician nutritionist "should individualize the meal pattern to distribute calories at meals and snacks throughout the day, including breakfast" [51]. Earlier recommendations maintained that eating small meals at regular intervals (four to six meals/snacks per day) could help maintain glucose levels; however, recent studies have not shown that higher eating frequency produces greater weight loss, and, for some, three meals per day leads to a significant reduction in A1c, appetite, and overall glycemia, with a decrease in daily insulin and improved glucose metabolism [51,66,67]. The most important counseling strategy is to help the person find a meal pattern that prevents times of heightened hunger, particularly in situations in which high-calorie food choices are readily available. For example, helping the patient plan healthy sack lunches and snacks may prevent overeating at vending machines or fast food establishments during working hours. Consuming a greater proportion of calories early in the day, as opposed to in the evening, may also prove to be beneficial to patients' weight loss goals [51].

Instruct patients to consider the following when reading Nutrition Facts labels [74,76]:

Instruct patients to consider the following when reading Nutrition Facts labels [74,76]:

Polyunsaturated fatty acids, such as omega-3 fatty acids, improve insulin sensitivity and may help reduce risk for cardiovascular disease by reducing triglycerides, increasing HDL cholesterol, and lowering blood pressure [21]. Good sources include salmon, sardines, herring, trout, and other fatty fish, as well as fish oil supplements. The ADA recommends an eating plan that is rich in monounsaturated and polyunsaturated fats to improve glucose metabolism [13]. Dietary guidelines recommend consuming at least two servings of non-fried fatty fish per week [68]. Linolenic acid is another type of polyunsaturated fatty acid and one of the three main omega-3 fatty acids that is believed to decrease blood clotting and inflammatory processes in the body. Because it cannot be synthesized by humans, it is considered essential in the diet [60]. Primary sources are canola oil, soybean oil, walnuts, flaxseed, and olive oil. Keep in mind that unsaturated fats contain the same amount of calories as saturated fat and that the diet should consist of no more than 10% of calories from fat [60].

Pre-exercise medical clearance is not necessary for asymptomatic individuals receiving diabetes care consistent with guidelines who wish to begin low- or moderate-intensity physical activity not exceeding the demands of brisk walking or everyday living. Individuals who plan to increase their exercise intensity or who meet certain higher-risk criteria may benefit from referral to a healthcare provider for a checkup and possible exercise stress test before starting such activities [88].

As noted, for the prevention of type 2 diabetes, the ADA recommends a minimum of 150 minutes of moderate-to-vigorous intensity aerobic activity per week, along with a healthful diet and modest calorie restriction. Aerobic exercise is defined as "rhythmic, repeated, and continuous movements of the same large muscle groups for at least 10 minutes at a time" [37]. Examples include walking, bicycling, dancing, water aerobics, and many sports [37]. Because the effect of exercise on insulin sensitivity does not last longer than 72 hours, patients will experience the most benefit to blood glucose if aerobic sessions are no more than two days apart [37,89].

Experts recommend resistance exercise be a component of the complete fitness program for healthy adults. Resistance exercise is defined as, "activities that use muscular strength to move a weight or work against a resistive load" [37]. Examples include weightlifting, working with resistance bands, and using weight machines.

It is also important to help patients select a program that will have the greatest chance for long-term maintenance. The ACSM has identified factors that influence maintenance of exercise behavior [89]:

After barriers to exercise have been identified, steps can be taken to help patients overcome them. For each barrier, ask the patient what he or she thinks could help; this will allow the patient to be actively involved in resolving the barriers. Then, provide suggestions to supplement the patient's problem-solving activity. Common barriers to exercise and suggestions for helping patients overcome them include:

The dominant theory describes a five-factor model that accounts for a majority of individual differences between people based on five personality traits and correlated exercise program considerations [100]:

As of 2023, no drug is approved by the FDA to prevent diabetes or treat insulin resistance. However, the ADA recommends that metformin therapy be considered for the prevention of diabetes in certain patients, including [13]:

As of 2023, no drug is approved by the FDA to prevent diabetes or treat insulin resistance. However, the ADA recommends that metformin therapy be considered for the prevention of diabetes in certain patients, including [13]:

Another drug, acarbose, was found to reduce the progression of IGT to type 2 diabetes by 25% over 3.3 years in one study [109]. Because this medication can cause significant gastrointestinal side effects, many subjects discontinued the study medication [105]. This raises questions about the efficacy and practicality of using acarbose to prevent type 2 diabetes in actual clinical practice [109].

Reviews and meta-analyses of publications concerning metabolic surgery have consistently found improvement or resolution of diabetes in the majority of patients. A 2010 study demonstrated that gastric banding surgery could induce a remission of existing type 2 diabetes, with 73% of the study group returning to normal glycemia. Another study indicated that gastric banding induced prolonged satiety and resulted in improved glycemic control. Of those who did not achieve euglycemia, glycemic control was improved [109]. This suggests that surgical intervention may be an appropriate approach for preventing diabetes in select patients who are unable to lose weight by other means. The ADA recommends metabolic surgery as an option to treat type 2 diabetes in screened surgical candidates with a BMI of 40 or greater (37.5 or greater in Asian Americans) and in adults with a BMI of 35.0–39.0 (32.5–37.4 in Asian Americans) who have type 2 diabetes and who do not achieve durable weight loss and improvement in comorbidities (including hyperglycemia) with nonsurgical methods [13]. Metabolic surgery may be considered as an option for adults with diabetes and BMI 30.0–34.9 (27.5–32.4 in Asian Americans) who do not achieve durable weight loss and improvement in comorbidities (including hyperglycemia) with tested efficacious nonsurgical methods [13]. After metabolic surgery, patients must receive ongoing lifestyle support and monitoring of micronutrient and nutritional status [13].

More research is necessary to determine how to address prediabetes in children. It is unknown whether children with prediabetes have the same degree of risk for developing type 2 diabetes as adults with prediabetes, or if the predictors for long-term risks of diabetes are the same for children [119,120]. The ADA recommends that risk-based screening for prediabetes and/or type 2 diabetes be considered after the onset of puberty or after 10 years of age, whichever occurs earlier, in children and adolescents with overweight (BMI 85th percentile or greater) or obesity (BMI 95th percentile or greater) and who have one or more of the following risk factors for diabetes [13]:

The CDC recommends that children and adolescents participate in at least 60 minutes of physical activity every day [122]. A study presented at the 2010 ADA annual meeting revealed that obese boys who engaged in aerobic and resistance exercise decreased their total body fat, visceral fat, and insulin resistance, even without any changes in diet [123]. The study also indicated that resistance exercise training is appealing to boys and that it expends similar energy to aerobic training in this population.

Tips for the family working to become more active include:

Diabetes is an urgent issue in the Latin American/Hispanic communities. Hispanic adults are 70% more likely than non-Hispanic White adults to be diagnosed with diabetes [131]. Rates of complications of diabetes are also higher among this group. Abdominal obesity and insulin resistance greatly increase the risk for metabolic syndrome in this population.

The traditional Hispanic diet is high in fruits, vegetables, and fiber, and low in fat. However, acculturation to the American diet has changed traditional preferences and practices to a less healthy style of eating. Healthy choices most likely to appeal to this population include [128]:

African Americans have a high prevalence of cardiovascular risk factors that may be reduced with lifestyle modification. These include obesity, hypertension, sedentary lifestyle, and tobacco use [127]. Unfortunately, studies have indicated that African Americans are less likely to participate in health screening programs. This is due in part to poor access, but may also stem from cultural and historical factors, such as mistrust of the healthcare system stemming from a history of inequitable treatment [127].

The incidence of diabetes among Asian Americans has increased more rapidly among those who have lived in the United States for a longer period of time than among new immigrants or those living in Asia [127]. Japanese individuals living in Seattle have diabetes prevalence four to five times that of those living in Tokyo [127]. Use of BMI is not as reliable a tool for predicting diabetes risk in Asian populations, as they tend to develop insulin resistance and type 2 diabetes at much lower indices [13,135]. The International Diabetes Federation has determined lower measures of waist circumference for determining health risk in Asian populations [135]. A systematic review of dietary self-management of diabetes among Asian Americans identified themes, including cultural beliefs about food, that characterize the cultural perspectives and experiences that influence diabetes self-management [136]. Patients reported receiving dietary recommendations that did not align with their beliefs about food as medicine and a source of balance in life and that recommendations to remove refined carbohydrates (e.g., rice) from their diets caused them to feel isolated from familiar and shared food habits and practices [136].

Perceived susceptibility is the first construct of the HBM. This may be reflected by the patient considering "What is the likelihood that I will get diabetes?" Patients who believe the risk is low will be less likely to make changes to prevent diabetes. Educating patients about the risk factors for diabetes will help them understand their susceptibility.

The U.S. Preventive Services Task Force has developed the Five A's protocol, a widely used framework for supporting behavior change in clinical settings [147]. The Five A's protocol can help structure an approach to help patients make health behavior changes. The Five A's are [147]:

The contemplation stage begins when a patient becomes less resistant to the idea of behavior change. However, he or she remains acutely ambivalent about change and continues to procrastinate. At this time, the person acknowledges the need for change but is held back by his or her reasons for staying the same. A typical contemplative statement would be, "I would really like to exercise, but I just don't have the time." Although the prospect of change within the next six months is characteristic of this stage, people can remain in contemplation for an extended period of time. Patients may be assisted through this stage by promoting their self-efficacy and supporting their efforts to gather information. Specific interventions include reflective listening, providing empathic feedback, and offering information and resources as appropriate. Motivational interviewing, to be discussed in more detail later, is a powerful method for helping precontemplative and contemplative people move further along in the process of change.

Topics included in diabetes prevention programs include [72,162]: