Diabetic complications are leading causes of blindness, amputations and kidney failure. Most diabetics develop a complication within 16 years of being diagnosed. Diabetologist's waiting rooms seem to be filled with people with white canes, overweight people, amputees in wheelchairs - people suffering the agonies of the darned.
A recent study I found called The Diabetes Control and Complications Trial followed two groups of insulin dependent diabetics, one following a casual regime of blood sugar control, the other attempting much tighter control with more frequent insulin injections. The results showed beyond doubt that high blood sugar is associated with neuropathies and microvascular (small blood vessel) complications, but does not lessen the macrovascular (large blood vessel) complications. In other words, tight control reduces the chance of kidney failure, foot problems, leg ulcers, blindness, amputation and neuropathy, but actually worsens weight gain, causes more and more severe hypoglycemia and increased risk of coronary artery disease (on the ADA-style high carbohydrate diet used in the DCCT).
The so-called microvascular complications are caused by high blood sugar and damage the capillaries and the organs dependent on them such as the kidneys (nephropathy), eyes (retinopathy), and the extremities which can lead to diabetic leg ulcers, gangrene and amputation. The neuropathies (nerve damage) include: itching, burning, numbness, and eventually the failure of organ systems to perform properly, as in delayed stomach emptying from damage to the vagus nerve, and eventually the progressive failure of the digestion.
The macrovascular complications - heart disease - are associated with and likely caused by high insulin levels: the so-called syndrome X. In this trial, the researchers acknowledge that high insulin levels are the price of tight control; and some of the tight control group gained weight and had increases in blood pressure and cholesterol, so they came to have an increased risk of vascular complications.. The larger vessels become blocked, like the coronary arteries which feed the heart muscle (setting the stage for heart attack), and the carotid artery which feeds the brain (setting the stage for a stroke). These conditions are shared with people without diabetes, but in diabetics they progress six times faster. Further, diabetics' blood has a greater tendency to clot, so that heart attacks and strokes are more common among them. The combination of numbness in the feet and poor circulation make diabetic feet and legs terribly vulnerable - even too-hot bath water can damage them - and wounds are slow to heal and may ulcerate.
So what can we as diabetics do about all this. Is it all just a "fait au compleat"?
All that really matters about complications is knowing how to avoid them. Our meds seem to mitigate the microvasular problems but I feel that giving up the high carb diet in place of something that promotes ketogenisis (low carb higher protein diet) is the answer to solving the macrovascular problem. This is something that not just diabetics can benefit from but that they happen to benefit from more than most.
So the long winded answer to your question is, NO, complications are not inevitable if you eat correctly and take the appropriate medications. AND of course get some exercise to help get your body into its proper metabolic state!!