The spectrum of plasma insulin responses in middle-aged and old non-obese diabetics with various degrees of metabolic derangement.

Abstract

Abstract. The plasma insulin responses of newly diagnosed, untreated, non‐obese, middle‐aged and old diabetics constitute a wide spectrum of responses varying with the metabolic state. The insulin response pattern after oral glucose in the mildest degree of glucose intolerance is characterized by a sustained rise in the plasma insulin concentration and a delayed decline towards the fasting level with a plasma insulin level higher than normal during the later part of the oral tests. The initial plasma insulin release in the mildest degree of glucose intolerance is, however, quite normal. In patients with more pronounced glucose intolerance the initial insulin response is proportionally more sluggish, and in severe glucose intolerance an overall diminishing of the insulin response obtains. After i.v. glucose and tolbutamide largely the same pattern is seen. The initial plasma insulin release in the mildest degree of glucose intolerance is normal. In patients with more pronounced glucose intolerance the initial insulin response is delayed, while only small changes occur during the later part of the insulin response. In the diabetics a significant positive correlation is found between the fasting plasma insulin and the fasting blood glucose concentration. A significant negative correlation is found in the diabetics between the fasting blood glucose and the increment from fasting to 15‐min and 2‐hour plasma insulin concentration in the oral tests and the increment from fasting to the 10‐min insulin value in the i.v. tests. There is, however, no correlation between the fasting plasma insulin and the 2‐hour plasma insulin concentrations in the oral tests in the diabetics. In the i.v. glucose tolerance test a significant inverse correlation exists in the diabetics between the fasting plasma insulin concentration and the increment from fasting to the 10‐min plasma insulin value, while such a correlation between the same parameters does not exist in the i.v. tolbutamide test.