Limiting Salt Lowers Blood Pressure and Health Risks in Diabetes

For patients living with diabetes, reducing the amount of salt in their daily diet is key to warding off serious threats to their health, a new review of studies finds.

In the Cochrane review, the authors evaluated 13 studies with 254 adults who had either type 1 or type 2 diabetes. For an average duration of one week, participants were restricted to large reduction in their daily salt intake to see how the change would affect their blood pressure.

“We were surprised to find so few studies of modest, practical salt reduction in diabetes where patients are at high cardiovascular risk and stand much to gain from interventions that reduce blood pressure,” said lead reviewer Rebecca Suckling. “However, despite this, there was a consistent reduction in blood pressure when salt intake was reduced.”

Suckling is part of the Blood Pressure Unit at St. George’s Hospital Medical School, in London.

The review appears in the current issue of The Cochrane Library, a publication of The Cochrane Collaboration, an international organization that evaluates research in all aspects of health care. Systematic reviews draw evidence-based conclusions about medical practice after considering both the content and quality of existing trials on a topic.

Patients with diabetes need to be extra cautious to maintain their blood pressure at an acceptable range of less than 130/80 mmHg. However, in the 2003-2004 period, 75 percent of adults with diabetes had blood pressure greater than or equal to 130/80 mmHg or used prescription hypertension medications, according to the American Diabetes Association (ADA).

High salt intake is a major cause for increased blood pressure and, in those with diabetes, elevated blood pressure can lead to more serious health problems, including stroke, heart attack and diabetic kidney disease. The ADA also reports that diabetic kidney disease is the leading cause of chronic kidney disease, accounting for 44 percent of new cases in 2005.

In the Cochrane review, the participants’ average salt intake was restricted by 11.9 grams a day for those with type 1 diabetes and by 7.3 grams a day for those with type 2.

The reviewers wrote that reducing salt intake by 8.5 grams a day could lower patients’ blood pressure by 7/3 mmHg. This was true for patients with both type 1 and type 2 diabetes. The reviewers noted that this reduction in blood pressure is similar to that found from taking blood pressure medication.

Suckling acknowledged that studies in the review only lasted for a week and that the type of salt restriction probably would not be manageable for longer periods.

“The majority of studies were small and only of a short duration with large changes in salt intake,” she said. “These studies are easy to perform and give information on the short-term effects of salt reduction.”

However, Suckling said, the review also found that in studies greater than two weeks, where salt was reduced by a more achievable and sustainable amount of 4.5 grams a day, blood pressure was reduced by 6/4 mmHg.

Diabetes specialist Todd Brown, M.D., of the Division of Endocrinology and Metabolism at Johns Hopkins University, said that practicing low-salt diets of these types is quite challenging for most patients with diabetes even though they know the health risks.

“The effects of salt on blood pressure are well known to health professionals and most patients, but what is less well known is where the salt comes from in our diet,” Brown said.

“The overwhelming majority comes from the processed foods that we eat,” he said. “If we are going to realize the benefits of sodium reduction on blood pressure and other health outcomes, we should focus less on the salt shaker and more on what we buy in the supermarket and at chain restaurants.”

Thank you Health Behavior News Service

Blood Sugar Management: Estimated Average Glucose

What Is Estimated Average Glucose?
Diabetes patients may be walking away from their medical appointments armed with new information to help them better improve and manage their diabetes. Like the familiar A1C test, the estimated average glucose, or eAG, is derived from glucose values taken over the course of three months.

The eAG, however, is not reported as a percentage but in the same values seen via daily self-monitoring – mg/dl or mmol/L. The formula for determining average glucose is 28.7xA1C-46.7 = eAG.

The following chart translates A1C percentages into eAG:

If your A1C is this:	eAG (Estimated Average Glucose) is this:
%	mg/dl	mmol/l
10.0%	240	13.4
9.0%	212	11.8
8.0%	183	10.1
7.0%	154	8.6
6.0%	126	7

The new eAG term was introduced to help stem confusion after a new worldwide standardization of A1C analyses was set. The new values are 1.5 to 2 percentages points lower than the current standard. In addition, the new values were reported in millimoles per mole (mmol/L), whereas A1C results were always reported as percentages.

An international study was then conducted to look at the relationship between HbA1c and average glucose. The A1C-Derived Average Glucose Study revealed a close relationship between HbA1C and AG (average glucose). This relationship is the eAG, which applies to patients with both type 1 and type 2 diabetes. This new terminology now focuses on a single set of values for both daily glucose checks and long-term control.  

SOURCE: American Diabetes Association. Estimated Average Glucose.
http://professional.diabetes.org/glucosecalculator.aspx

Diabetes: What Is The Ideal Insulin Injection-Meal Interval?

I have always asked doctors what is the ideal interval between taking an insulin injection and starting a meal. Because regular insulin does not lower blood glucose immediately after injection many physicians recommend an injection-meal interval (IMI).

By asking patients to inject well before beginning a meal, these physicians hope to compensate for the lag time between the injection of insulin and its onset of action. 

Hubert Overmann, Lutz Heinemann tried to find out what physicians recommend to their patients with respect to the IMI when prescribing intensive insulin therapy. A total of 58 diabetologists were surveyed by means of a structured questionnaire.

A fixed IMI of 15 (0–30) min [median (range)] was recommended by 29% of the 58 diabetologists, and a flexible IMI was recommended by 71%. The minimal interval for the suggested flexible IMI was 0 min and the maximal interval 45 min (median 23 min).

The researchers compared these results with findings of 192 patients with type 1 diabetes from a population based study. In this study patients were asked by questionnaire about their daily life handling of the IMI.

Among the group of 134 patients reporting use of a flexible IMI, 62% used an IMI of ≤15 min, 16% one of 20–25 min, and 21% one of ≥30 min. There were 12 patients using a flexible IMI who adapted it so frequently that they could not state a typical interval. A total of 58 patients (30%) used a fixed IMI (67% used an IMI of ≤15 min, 7% one of 20–25 min, 26% one of ≥30 min).

The surveys showed that diabetologists advocating intensive insulin therapy usually recommend an IMI shorter than 30 min. The majority of patients (75%) with type 1 diabetes use an IMI of <30 min in daily life.

In sum, most doctors say the interval should be between 15 to 30 minutes. However, some recommend that a patient must wait till the action of the insulin is at its optimum (determined by taking a reading at 15-minute intervals) before starting a meal.

But such recommendations just cause more confusion. Still, for good BS control, an insulin-dependent diabetic would be better off knowing when to start eating.

I came across this oft-cited article by ME Lean, LL Ng, and BR Tennison and its summary in the British Medical Journal that sheds some light on the subject. Though no clear-cut answers are provided, it's good to know what researchers have discovered. 

In a survey of 225 diabetics treated with insulin, 24 (10.6%) claimed never to have received advice concerning the interval between insulin injection and eating. Of the remainder, 67 (33%) admitted disregarding advice and using shorter intervals.

There was a significant (p less than 0.01) difference between the reported frequencies of clinical hypoglycaemia in patients using different intervals.

The effects on glucose control of intervals between insulin injection and breakfast of zero, 15, 30, and 45 minutes were studied for periods of one week in 11 patients with type I diabetes who were receiving twice daily injections of monocomponent porcine insulins and high fibre, high carbohydrate diets, using standard home blood glucose monitoring techniques to measure blood glucose concentrations each morning.

The delay of 45 minutes resulted in the lowest frequency of hypoglycaemia and the most acceptable pattern of glucose concentrations measured one and two hours after breakfast and before lunch. Combining results obtained at these three times, the mean increment in blood glucose concentration was smaller after allowing a delay of 45 minutes than after delays of zero (p less than 0.001), 15 (p less than 0.03), and 30 (NS) minutes.

A delay of 30 minutes resulted in smaller mean increments in blood glucose concentration than did delays of zero (p less than 0.001) and 15 (NS) minutes. These results suggest that this aspect of diabetic management may be neglected, with important consequences for blood glucose control.

An increase in delay between insulin injection and eating to 45 minutes would be a simple and safe way of improving blood glucose control in at least the 37% of the diabetic population surveyed in this study who currently allow less than 15 minutes.