19

Diabetes and Insulin
Resistance
Food and Nutrients in
Primary Care
Mark Hyman, M.D., Jayashree Mani, M.S., and Russell Jaffe, M.D., Ph.D.

INTRODUCTION
This chapter focuses on solutions to obesity and diabetes that are cost and outcome effective, evidence based, and encouraging in their potential to improve health while lowering health care costs.
These two disorders now exceed malnutrition in global public health costs and life lost. Recent
National Health and Nutrition Examination Survey (NHANES) data of Americans 2003–8 show that nearly 75% of the US population is now overweight [1]. Childhood obesity has increased threeto fourfold since the 1960s [2]. In 1980, no states had obesity rates over 15%; by 2010, every state had an obesity rate greater than 20% [3].

EPIDEMIOLOGY AND PATHOGENESIS
Diabetes prevalence has risen sevenfold since 1983. In 2010, diabetes was diagnosed in approximately 25 million adults in the United States, including a prevalence rate of 26.9% in seniors
> 65 years [4]. Diabetes and obesity together also place an enormous economic burden on our society. The direct and indirect annual costs of obesity in the United States are $113 billion and $174 billion for diabetes, cumulatively $3 trillion over the past decade [5]. The problem is also expanding globally. In China, 92 million individuals have diabetes, 60% of whom are undiagnosed. Another
148 million have metabolic syndrome, 100% of whom are undiagnosed [6].
Overweight and obesity are, for the majority, markers of a single unifying metabolic d­ ysfunction.
Population wide, risk stratification is based on profiles of body weight associated with increased risk. Overweight is expressed as a body mass index (BMI) > 25; obesity is defined by a BMI > 30.
Health risks increase progressively with higher BMI. Clinically, this profile is less useful than considering metabolic dysfunctions as a continuum from optimal insulin sensitivity to end-stage diabetes. In childhood, both low weight and accelerated weight gain affect glucose tolerance and the risk of type 2 diabetes [7]. In adulthood, weight gain is the primary precursor to diabetes. This spectrum

373

374

Advancing Medicine with Food and Nutrients, Second Edition

has been referred to as “diabesity” and is a more useful clinical concept, focusing on mechanism rather than phenotype for obesity.

MORTALITY AND MORBIDITY
Obesity shortens lifespan by nine years of life for the average person [8]. In adolescence, obesity creates the same risk of premature death as heavy smoking [9]. Diabesity along the entire continuum of metabolic dysfunction is the primary driver of diabetes, cardiovascular disease [10], stroke, dementia [11], cancer [12], and most chronic disease mortality [13]. A recent 40-year prospective study of 4857 Pima Indian children found that the major predictor of premature death was insulin resistance, not hypertension or hyperlipidemia. Pima Indians in the highest quartile of glucose intolerance had a 73% increase in early death rate compared to those in the lowest quartile [14]. In the past, when these same Native Americans lived an active nomadic life they showed little evidence of insulin resistance. This suggests that insulin resistance is a classic epigenetic or lifestyle-acquired condition, based largely on how we eat, drink, think, and live.

MAJOR STUDIES ON LIFESTYLE FACTORS
We know from the evidence that lifestyle is an important factor in the development of insulin resistance. In one diabetes prevention trial, evidence for the importance of exercise and nutrition became so compelling that it was deemed unethical to deny exercise and good nutrition to the control group and the study was halted [15]. As a result of this type of data, we no longer take lifestyle for granted [16]. In the 27-center study cited here, researchers found that when patients at risk for diabetes lost just eight pounds through regular exercise, the incidence of type 2 diabetes was reduced by 58%.

RISK