Diabetes encompasses a group of complex, chronic, and progressive diseases that are primarily defined on the basis of hyperglycemia.
Two major types of diabetes are recognized and include Type 1 diabetes and Type 2 diabetes. Type 1 diabetes, which accounts
for ∼5% of diabetes cases, is caused mainly by immune-mediated pancreatic B-cell destruction leading to absolute insulin deficiency.
Type 2 diabetes, which accounts for the majority of patients (90–95%), features a multifactorial pathogenesis involving defects
in both insulin action and insulin secretion as a result of a complex interaction of genetic and environmental influences.
Key Points • The overlapping syndromes of prediabetes and metabolic syndrome place individuals at increased risk of Type 2 diabetes and
cardiovascular disease, and in aggregate, these disorders comprise the spectrum of cardiometabolic disease. Treatment of these
prediabetic states is critical for reducing patient suffering and social costs attributable to the increasing prevalence of
diabetes worldwide.
• Insulin resistance is central to the pathophysiology of Type 2 diabetes and metabolic syndrome. While obesity can exacerbate
insulin resistance, it is abnormal lipid accumulation in visceral adipose tissue, and in skeletal muscle cells and hepatocytes,
that appear to be more potent and independent mediators of cardiometabolic disease.
• Cardiometabolic disease can be effectively treated or prevented using nutrition as a component of lifestyle therapy, which,
given the underlying pathophysiology, will need to augment insulin sensitivity, enhance insulin secretion, and/or ameliorate
cardiovascular risk factors. This can be accomplished via hypocaloric feeding or altered macronutrient composition of the
diet.
• Hypocaloric diets resulting in 5–10% weight loss are effective over a wide spectrum of caloric composition ranging from
low carbohydrate to low fat.
• Isocaloric diets can also improve insulin sensitivity and cardiovascular risk factors particularly if enriched in monounsaturated
fat or fiber with reduced intake of saturated fat.
• Genome-wide association studies have confirmed multiple susceptibility loci (i.e., gene-based single nucleotide polymorphisms—SNPs)
for Type 2 diabetes and obesity and present a powerful paradigm for the identification and study of nutrient–gene interactions,
provided that investigators measure diet as an environmental variable.