For most type two diabetics high blood pressure is part of the diabetes deal. And the standard advice from the medics is drop the salt. Salt they tell us will do our blood pressure no good at all. Excessive levels of salt does no-one any good, very much like insulin levels, but as with insulin, too low a level leads to serious problems. If you start a low carb diet and prepare all your own food and avoid added salt, you may be going too low on salt. Think about it, many of us were eating ready meals and factory made foods before low carbing and many of these foods have a very high salt content. We have quickly gone from a high salt diet to a possibly very low salt diet.
“When you cut the carbs your kidneys will release sodium. This is why people lose some water initially and why blood pressure also tends to get better on low-carb. If you are not careful to replace the lost sodium sufficiently by adding salt to your food, you will experience the effects of mild hypo-natremia. These are: headache, constipation, weakness, fatigue, low-blood pressure, othostatic hypotension and possibly leg cramps. If you get a blood test you may find that your potassium is low, too. Unfortunately, there is no reliable blood test for magnesium but it may also be low. Supplementing with salt should correct these problems. You don't need to take a potassium supplement, it will correct if you eat enough salt. Some people will have a persistent magnesium deficiency that will require supplements. This would be manifested by leg cramps and hyper-reflexia (something your doctor can check). To correct this you should take a slow-release Mg++ supplement daily.
Many people make the mistake of restricting salt and drinking lots of water when on a low carb diet. This is virtually guaranteed to cause problems. When you look carefully at the studies that report equivocal results with a low-carb diet, this is invariably one of the reasons.”