Impaired β‐cell function in the presence of reduced insulin sensitivity determines glucose tolerance status in acromegalic patients

Abstract

We conclude that insulin sensitivity is reduced to a similar extent in acromegalic patients with normal glucose tolerance and those with impaired glucose tolerance or diabetes. Compensatory hyperfunction of beta-cells appears to counterbalance the reduced insulin sensitivity in the acromegalic patients with normal glucose tolerance but not in those with impaired glucose tolerance or diabetes.

Impact of successful transsphenoidal surgery on cardiovascular risk factors in acromegaly

“…Normalization of glucose tolerance in the present study was accompanied by an impressive improvement in insulin sensitivity, as shown by significant changes in both HOMA ISI and OGTT ISI . This is in agreement with the findings of studies based on the euglycaemic clamp (26,27) and with recent data on short-term postoperative HOMA ISI (30). Taken together, these results suggest that insulin sensitivity can improve quite quickly after surgery, whereas normalization of glucose tolerance in patients with acromegaly requires a sustained improvement of GH/IGF-I hypersecretion and insulin sensitivity.…”

“…In the present study, preoperative insulin sensitivity was impaired compared with that in controls regardless of BMI, and no significant difference in insulin sensitivity could be found between patients with NGT and IGT, supporting the view that insulin resistance is a common event in patients with acromegaly and that only those who fail to counterbalance the reduced insulin sensitivity with increased b-cell function develop IGT and diabetes mellitus (30). Interestingly, the marked postoperative improvement in insulin sensitivity observed in cured patients occurred without significant changes in BMI.…”

“…In contrast, IGT and diabetes mellitus, which were present in about 33% of the patients with active disease, were found to normalize in all cases of successful surgery. Although it extends our previous findings in a smaller series of elderly patients with acromegaly (23), this point is in apparent contrast with data in a recent report of a short-term postoperative study -7 -14 days after surgery -in which glucose tolerance was normalized only in a subset of successfully operated patients (30). Normalization of glucose tolerance in the present study was accompanied by an impressive improvement in insulin sensitivity, as shown by significant changes in both HOMA ISI and OGTT ISI .…”

“…The difficulty of assessing insulin sensitivity with such sophisticated techniques, which hampers the study of large series, can be overcome by the use of variable indexes of insulin sensitivity (ISI), which can be simply deduced from measurements of plasma glycaemia and insulinaemia, obtained either in fasting conditions according to the homeostatic model assessment (HOMA) (28) or during an oral glucose tolerance test (OGTT) (29) -the latter index correlating best with data obtained by euglycaemic clamp (29). These parameters are also applicable to patients with acromegaly, and a recent study based on the use of the HOMA index has suggested that insulin resistance is reduced in these patients, regardless of their glucose tolerance status, patients who fail to counterbalance insulin resistance with an increased b-cell function developing glucose intolerance or diabetes (30).…”

Management of Hyperglycemia in a Patient with Acromegaly Treated with Pasireotide LAR: A Case Study

“…However, treatment with pasireotide had minimal effects on hepatic or peripheral insulin sensitivity. In addition to drug-related effects, prolonged exposure to excess GH and IGF-1 in patients with acromegaly is associated with decreased insulin sensitivity (8).…”