Whilst at a population level there is very strong correlation between obesity and Type 2 Diabetes (T2D), this is far from predictable at an individual level. Irrespective of definition used, a significant proportion of obese individuals are non-diabetic. These individuals have no clear clinical phenotype, and are not necessarily free of other metabolic abnormalities. Aside from glycaemic parameters, detailed investigations are, again, not particularly illuminating. For example, adipose distribution, fitness or routine biochemical parameters are not accurate predictors. From a genetic perspective, genome wide association studies show surprisingly little overlap between obesity and T2D “genes”, and much more work remains to be done to identify genetic characteristics of the obese non diabetic. The clinical issue presented by the obese non diabetic is whether or not there is increased mortality risk? With regards cardiovascular risk obesity per se is not a strong risk predictor, and there is little information regarding cancer risk. Logically, obese non diabetics should be at increased risk of orthopaedic, respiratory and sleep abnormalities but this also is not clear, not least because the underlying pathophysiology of these obesity “complications” is yet to be fully elucidated.