To beat your diabetes you need to eat food that is low in sugar, low in fat, low in salt, high in fibre and has low GI values, ie it releases glucose into your bloodstream relatively slowly. Some kinds of bread fit this bill; others do not.
Sourdough Bread is made from flour, ie grain that has been ground into powder. Common wheat is usually used because its flour has high levels of gluten, which gives the dough sponginess and elasticity. But bread is also made from other species of wheat (eg, durum and spelt) and other grains such as rye, barley, corn (maize) and oats. The non-wheat grains usually have wheat flour mixed into the flour.
The quality of bread depends largely on the protein content of the flour. The best breads use flour with 12 to 14% protein rather than all-purpose wheat flour which only contains 9 to 12% protein.
Whole grains or refined grains?
When cereal grains such as wheat are harvested they are surrounded by a tough protective coating called a husk. Before you can eat the grains, the husk has to be removed. This is done by threshing (beating the grains) and winnowing (blowing away the chaff, ie the broken off bits of husk).
The grain without its husk is called a groat. It consists of three main parts: the endosperm, germ and bran. The endosperm is the main tissue inside the grain and provides nutrition in the form of starch, protein and oils.
The germ is the embryo, the reproductive part that germinates and grows into a plant. It is surrounded by the endosperm. The germ contains several essential nutrients. Wheat germ, for example, is a concentrated source of vitamin E, folate, phosphorus, thiamine, zinc and magnesium, essential fatty acids and fatty alcohols.
Bran is the hard outer layer of grain. It is rich in dietary fibre and essential fatty acids and contains starch, protein, vitamins and minerals. As you can see, the germ and bran contain lots of healthy stuff that is not found in the endosperm.
Whole grains are cereal grains in their natural state, ie they contain all three main parts, endosperm, bran and germ. Refined grains are groats from which the bran and germ have been removed by grinding and sifting.
Refining causes the grains to lose some of their nutritional value. Sometimes nutrients such as vitamins are added back. But, as these represent a small fraction of the nutrients removed, refined grains are nutritionally inferior to whole grains.
Removing the bran and grinding the grains into a fine powder increases the glycemic index value (GI) of the grain, ie you digest glucose from refined grains quicker than glucose from whole grains which, as a diabetic, is not what you want. It is the high fibre in the bran of the whole grains which slows the release of glucose.
Whole grains are great for our health in many other ways, thanks to their high levels of vitamins and minerals. Most whole grains are particularly rich in B vitamins. Whole grains also have plenty of protein.
One of these proteins is gluten. Gluten makes dough elastic, which helps it to rise and keep its shape. It constitutes about 80% of the protein in wheat seed, which is one reason why wheat is popular for bread-making. It is also found in barley and rye.
Bread is made by mixing up dough, a paste of flour and water (or other liquid). The dough is usually leavened (see below), allowed to rise, and then cooked.
Breads may also contain extra ingredients, such as salt or butter, to improve taste. Improvers are additives used to quicken the rising time, increase volume and enhance texture. Salt is one of the most common improvers; it is used to enhance flavour and the crumb (the inside of the bread) by strengthening the gluten. Improvers may include ascorbic acid and ammonium chloride.