This recent study of 245 women over 60 found that those eating proportionally more protein and less carbohydrate in their diets had a reduced chance of having Metabolic Syndrome. This is a syndrome in which the combined effect of a number of health issues, including Insulin Resistance, create significant health risk to individuals, so it's a good thing to avoid.
It's worth remembering that there could be many reasons beyond just the food choices made that contributed to a reduced risk of Metabolic Syndrome: maybe people eating more protein were also more health conscious and doing more physical activity. Another possibility is that those eating more carbohydrate were getting that from high sugar foods and drinks. In older people sugar in foods is not always a problem in itself, but the most nutrient dense carbohydrate foods are things like potatoes and other starchy vegetables, grain foods and dairy foods - all of which also offer lots of important nutrients that are lacking in high sugar convenience foods, beverages or confectionery: so that could be part of the picture also.
What is clear is that this is more support for a protein food at the centre of every meal - surround that with plenty of colour from veges, salad, fruits, nuts, seeds and grains and you cant go wrong!