Clonidine as an antihypertensive drug in diabeticsSD Bhandarkar, KS Vernekar
Department of Diabetes & Endocrinology, K.E.M. Hospital, Parel, Bombay 400 012, India
Correspondence Address: Source of Support: None, Conflict of Interest: None PMID: 722616
Source of Support: None, Conflict of Interest: None
Clonidine was administered as an antihypertensive agent to 20 diabetic patients stabilized on oral hypoglycemic agents. The study lasted for three months. Sixteen patients completed the study. No patient complained of hypoglycemic symptoms. All patients showed a good control of blood pressure. Only two patients showed a rise in post lunch blood sugar level on one occasion each during treatment. There was no significant change in the blood sugar levels in the remaining patients. In conclusion, clonidine does not appear to significantly alter the diabetic control by oral hypoglycemic drugs.
Clonidine is a useful antihypertensive drug. Hypertension and diabetes are both common diseases and frequently co-exist. The following study was undertaken in the Diabetes Clinic of the K.E.M. Hospital Bombay, to determine if clonidine had any deleterious effect on the regulation of the diabetic state.
Literature on this subject is scant and comprises mostly of the experimental work in animals. Clonidine has been shown to produce the following effects: (1) hyperglycemia following an injection into the vertebral artery in cats  (2) reduction in catecholamine release in response to hypoglycemia in man  and (3) increased hepatic glycogenolysis following intravenous administration in cats. 
Twenty diabetic patients with hypertension were studied. They were selected on the following basis.
Patients with following were not considered for this study:
Only those patients who were well controlled for at least 6 months with oral hypoglycemic drugs were selected because in such patients a change in the blood sugar, if any, could possibly be attributed to the added drug, clonidine. Patients treated with insulin were excluded because many of them tend to have fluctuating blood sugars and, therefore, it would be difficult to separate the effect of clonidine on blood sugar level, if any, from the spontaneous fluctuations in the latter.
All the patients had a fasting and postlunch true blood sugar determination (Nelson Somogyi method) before commencing the study and at monthly intervals for 3 months (which was the duration of the study). They had their blood pressure in the right arm determined in the sitting position before commencing the study, and at 15 days' intervals during the entire period of study.
The patients were supplied clonidine tablets* for 8 days at a time and at every visit they were questioned by the same person (K.S.V.) about the appearance of any new symptoms since their last attendance.
Clonidine was started in the dose of 50 µg 3 times a day and the dose was gradually increased at weekly intervals to a maximum of 200 µg. 3 times a day.
[Table 1] shows the results.
Sixteen patients completed the 3 months' trial, 2 patients dropped out on their own, and the drug had to be discontinued in 2 patients because of adverse effects. The blood pressure was well controlled in all patients. The average dose of 'clonidine was 282 µg/day in 3 divided doses, the range being 150-500 µg/day.
The mean systolic blood pressure of the whole group was 168.6 mm.Hg. and the mean diastolic blood pressure, 105, mm. Hg. before the treatment. During the treatment the mean systolic blood pressure of the group was 148 mm. Hg. and the mean diastolic blood pressure, 91.5 mm. Hg Thus there was a drop of 20.6 mm. Hg. systolic and a drop of 13.9 mm. Hg. diastolic pressure in the whole group. It took an average of two weeks for blood pressure to be controlled, the range of 1 to 6 weeks.
The mean fasting blood sugar level before commencing clonidine was 99.2 mg.% and the mean post lunch blood sugar level was 110.6 mg%. While on the drug, the figures were 94.7 mg% and 112.6 mg%, respectively.
In two patients, one intra-treatment post lunch blood sugar value was higher than the pretreatment post lunch blood sugar value by 60 mg% and 32 mg% respectively.
Two patients complained of unpleasant symptoms; one had persistent giddiness and frequent vomiting, and the second had generalised weakness, malaise, muscular pains, nausea and involuntary movements of limbs. Clonidine was omitted in these two patients. No patient complained of hypoglycemic symptoms.
As diabetes and hypertension frequently coexist, it is useful to have an antihypertensive drug which does not alter the carbohydrate tolerance adversely. Thiazides  and diazoxide , have been reported to cause hyperglycemia. Propranolol  and gaunethidine , are known to potentiate the hypoglycemic effects of insulin and oral hypoglycemic agents. In this short-term study, we did not observe any deleterious effect of clonidine on the control of diabetes with oral hypoglycemic agents, except in two patients in whom elevation of single post lunch blood sugar values was seen during treatment. The blood pressure was controlled satisfactorily in all patients. Only two patients complained of unpleasant symptoms which necessitated discontinuation of clonidine.
This study was carried out under the auspices of the Seth G.S. Medical College and K.E.M. Hospital Research Society with financial assistance by M/s. Unichem Laboratories Ltd. We are grateful to both of them. We thank Mrs. K. D. Lotlikar, M.Sc., Bio-statistician, for carrying out statistical analysis of the data. Finally, we thank the Dean, Seth G.S. Medical College & K.E.M. Hospital, for permission to carry out the above study and to publish this report.