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Effect of Sulphonylurea Therapy on Plasma Insulin, Intact and 32/33 Split Proinsulin in Subjects with Type 2 Diabetes Mellitus
Author(s) -
Davies M. J.,
Metcalfe J.,
Day J. L.,
Grenfell A.,
Hales C. N.,
Gray I. P.
Publication year - 1994
Publication title -
diabetic medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.474
H-Index - 145
eISSN - 1464-5491
pISSN - 0742-3071
DOI - 10.1111/j.1464-5491.1994.tb00274.x
Subject(s) - proinsulin , medicine , endocrinology , insulin , diabetes mellitus , type 2 diabetes mellitus
This study was undertaken to clarify the effect of sulphonylurea therapy on beta cell function in 27 subjects with newly diagnosed Type 2 diabetes mellitus. Plasma glucose, insulin, intact and 32/33 split proinsulin were measured at diagnostic OGTT. After 8–12 weeks on a conventional diet, subjects with a fasting glucose > 9 mmol I −1 ( n = 12) were commenced on sulphonylurea therapy. At diagnosis, the sulphonylurea requiring group were more hyperglycaemic ( p < 0.0001), less obese ( p <0.05) and more insulin deficient with a lower 30 min insulin ( p < 0.0002) than the diet group. Following dietary intervention in the sulphonylurea group, weight remained unchanged but there was a reduction in fasting glucose ( p < 0.009). Fasting insulin, intact proinsulin, and 32/33 split proinsulin remained unchanged. After 12 weeks of sulphonylurea therapy there was a weight gain of 1.5 kg ( p < 0.01), but a reduction in fasting glucose ( p < 0.0001). Fasting insulin and intact proinsulin increased ( p < 0.004) but 32/33 split proinsulin remained unchanged. There was a significant increase in both the fasting insulin to glucose ratio ( p < 0.005), and the intact to 32/33 split proinsulin ratio ( p < 0.02). Final fasting glucose following sulphonylurea therapy was positively correlated with the initial intact and 32/33 split proinsulin and the fasting glucose following dietary treatment. It is clear from this work that sulphonylureas have a complex effect on beta cell physiology and as well as stimulating release of insulin they increase the release of intact proinsulin but not that of 32/33 split proinsulin, hence they increase the intact to 32/33 split proinsulin ratio.