Diabetes is emerging as one of the most significant diseases to threaten human health in modern times. Type 2 diabetes mellitus is predicted to affect more than 300 million people by 2025, and currently, 1 in 10 children worldwide are obese, or grossly overweight. The huge increase in the numbers of individuals affected by type 2 diabetes is associated with poor diet, high calorie food intake and a collapse in physical activity in many populations throughout the world. The concept of the ‘thrifty gene’ hypothesis has emerged to explain this phenomenon. 1 Simply stated, humans have evolved to be able to cope with the alternating periods of starvation and plenty that regularlyconfronted out ancestors. We therefore have evolved to rapidly and efficiently store energy in the form of lipid in adipose tissue to enable us to survive periods of famine. Clearly, until recent times, this conferred an evolutionary advantage. In the modern era of widely available and abundant food, this genetic make up is no longer advantageous, but instead results in obesity and predisposes to diseases such as type 2 diabetes. The term ‘malnourished’ used to refer exclusively to people who had inadequate food intake, but now can equally well be applied to individuals who have excessive and inappropriate food intake. Dentists have long been aware of the importance of a diagnosis of diabetes in their patients. Various oral conditions are associated with diabetes, including dry mouth, candidal infections, delayed wound healing and periodontal disease. Periodontitis was described as the sixth complication of diabetes in 1993, together with retinopathy, nephropathy, neuropathy, macrovascular disease and altered wound healing. 2 The links between periodontal disease and diabetes were not so well recognised by the medical community until rather more recently. Thus, in 2003, the American Diabetes Association stated that ‘hypertension, abnormalities of lipid metabolism, and periodontal disease are often found in people with diabetes’. 3 Much of the prevalence data linking periodontal disease and diabetes was gathered in studies of the Pima Indians. This population of native Americans in Arizona has an unusually high prevalence of diabetes. The reason for this may be linked to the thrifty gene hypothesis. 1 The rivers that this population depended upon for crop irrigation were diverted by European settlers to the region, leading to crop failure and widespread starvation among the Pima Indians. Those who survived would be more likely to possess the thrifty genotype, leading to the enrichment of this genotype in the modern day Pima population. In present times of plenty, this has resulted in a hugely increased prevalence of type 2 diabetes in this population, with more than half the individuals affected. EarlystudiesofdiabetesandperiodontaldiseaseinthePima