Insulin sensitivity decreases with obesity, and lean cats with low insulin sensitivity are at greatest risk of glucose intolerance with weight gain

Abstract

This study quantifies the effects of marked weight gain on glucose and insulin metabolism in 16 cats which increased their weight by an average of 44.2% over 10 months. Significantly, the development of feline obesity was accompanied by a 52% decrease in tissue sensitivity to insulin and diminished glucose effectiveness. In addition, glucose intolerance and abnormal insulin response occurred in some cats. An important finding was that normal weight cats with low insulin sensitivity and glucose effectiveness were at increased risk of developing impaired glucose tolerance with obesity. High basal insulin concentrations or low acute insulin response to glucose also independently increased the risk for developing impaired glucose tolerance. Male cats gained more weight relative to females and this, combined with their tendency to lower insulin sensitivity and higher insulin concentrations, may explain why male cats are at greater risk for diabetes. Results suggest an underlying predisposition for glucose intolerance in some cats, which is exacerbated by obesity. These cats may be more at risk of progressing to overt type 2 diabetes mellitus.

Fig 1.

Mean plasma glucose (1A) and insulin (1B) concentrations during a glucose tolerance test in 16 cats before and after becoming obese. Values in obese cats (—□—) are significantly (^* P <0.05 and ^** P <0.001, respectively) different from values in lean cats (—♦—).

Fig 2.

Mean area under the insulin response curve during the first 10 min, the first hour and the second hour after clucose administration in 16 cats before and after becoming obese. Values in obese cats (▪) are significantly (^* P<0.05) different from values in lean cats (□).

Fig 3.

Mean plasma glucose (3A) and insulin (3B) concentrations in 16 lean cats (—♦—), in nine obese cats which maintained normal glucose tolerance after weight gain (NGT; —□—), and in seven obese cats which developed impaired glucose tolerance after weight gain (IGT; —▴—). Values which do not have a common superscript letter differ significantly.

Fig 4.

Mean plasma glucose (4A) and insulin (4B) concentrations during a meal response test in obese cats with normal glucose tolerance (NGT;——) and in obese cats with impaired glucose tolerance (IGT; —□—). †Values in cats with impaired glucose tolerance are significantly (P<0.05) different from values in cats with normal glucose tolerance. ^*Values significantly different from baseline.

Fig 5.

Mean plasma glucose (5A) and insulin (5B) concentrations during a meal response test in obese male and female cats. Values in obese male cats (—♦—) are significantly (^* P<0.05) different from values in obese females (—□—).