Brief Answer: Error in checking Detailed Answer: Hello Thanks for the query Isolated systolic hypertension is very well known however isolated diastolic hypertension is most often due to faulty checking or because of loss of calibration of the automated machines. The reason for isolated diastolic hypertension is the normal systemic hypertension itself, in your case is most likely due to sleep apnea. I advice you to re check your blood pressure using a different apparatus or at a hospital. I hope I was of help, if you have any further queries please get back to me. I wish you good health Regards

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