Effect of alpha-1-blockade by prazosin on blood sugar, insulin and glucagon levels in normals and non-insulin dependent diabetics

Abstract

The AA. studied the glycometabolic activity of prazosin, a hypotensive drug with an adrenergic blocking activity of alpha-1-selective type. Twenty-two moderately hypertensive subjects were studied. Their ages ranged from 37 to 57 years; 10 of the patients had non-insulin dependent diabetes mellitus. After overnight fasting every patient underwent an oral glucose test (g 100) at 09:00. Blood samples were withdrawn at 0, 30, 60, 90 and 120 minutes. Each patient was then given in randomized and double-blind fashion placebo or prazosin (4 mg, 2 pills of Minipress Pfizer per day) for the following 7 days; then another glucose load was administered. Glucose (enzymatic method), insulin and glucagon (RIA method) were measured in each blood sample. In non diabetic subjects glucose levels (60, 90, 120 min and total area) after oral glucose and prazosin were statistically higher (p less than 0.05, p less than 0.01, p less than 0.05) than after glucose only. No significant difference between the two curves was observed in the diabetic group. IRI levels in normal subjects were statistically higher after 120 min and in the total area, while no evident changes were noted in the diabetic group. The glucagon curve seen after oral glucose was not modified by prazosin in either group.

Caffeic acid phenethyl amide improves glucose homeostasis and attenuates the progression of vascular dysfunction in Streptozotocin-induced diabetic rats

“…In addition, in the present study, CAPA was found to inhibit α-adrenergic receptors on vascular tissue. Since inhibition of sympathetic α-adrenergic receptors is reported to enhance insulin release [52], the stimulation of insulin release by CAPA may be partly attributed to inhibition of α-adrenoceptors. In STZ-induced type 1 diabetic rats, CAPA lowered plasma glucose levels even though this diabetic rat model has low insulin secretion activity, suggesting that insulin-independent mechanisms may be involved.…”

Drug Treatment of Hypertension in Patients With Diabetes Mellitus

“…In patients with diabetes and hypertension, similar effects have been noted. Several investigators reported that prazosin did not alter glycemic control (229,236), and others found a significant, although small, decrease in GHb levels (76,233) and improved glucose tolerance (232).…”

META‐ANALYSIS OF STUDIES USING SELECTIVE α1‐BLOCKERS IN PATIENTS WITH HYPERTENSION AND TYPE 2 DIABETES

“…Of the 27 clinical studies evaluating the use of an α 1 ‐blocking agent in patients with type 2 diabetes, 22 were included in the analysis (Table 2). 17,18,20,29–47 In these studies (published between 1980 and 1995), the number of subjects ranged from 5 to 70, and the study duration ranged from 1 week to 21 months (mean 18.8 weeks).…”

“…Twelve studies•(Table 2: studies 1, 7, 8, 10, 11, 13, 14, 16,17,19,20,22) reported changes in HDL cholesterol: 11 with doxazosin and one with bunazosin. As shown in Table 3, for all selective a 1 -blockers and for doxazosin alone, the results showed statistically significant increases in HDL cholesterol (mean changes of0.12 and 0.13 mmol/1, respectively).…”

“…Various studies have shown that the quinazoline class of antihypertensive agents, which act by blocking the postsynaptic α 1 ‐adrenergic receptor, have advantageous effects on plasma lipid profiles and insulin sensitivity 16 . The findings have not been entirely consistent between studies, however, and questions have been raised about the metabolic safety of this class of agents in patients with diabetes 17–21 . Additionally, postural hypotension and syncope associated with the use of α‐adrenergic blocking agents have been viewed as a particularly important issue in diabetic patients, who often demonstrate autonomic neuropathy 21 .…”