There are many things that could cause kidney problems. Most likely, since you have been diabetic for so long, you are experiencing a complication from diabetes.
Microalbuminuria means you are spilling small protein cells into the urine. This means the barrier between the kidneys and some of the waste products (protein) isn't properly filtering, and it is letting small protein cells slip through. Creatinine also has to do with the breakdown and filtration of protein. If your GFR (glomerular filtration rate) is normal, you can reverse the damage to your kidneys and not suffer any long term effects. Once your GFR starts to deteriorate, the damage has become permanent. No worries though--this takes a long time to happen!
I began spilling protein into my urine 11 years ago. I began taking an ACE (angiotensin converting enzyme) inhibitor drug and it reversed the damage to my kidneys (only minor damage, which would be similar in your case). ACE inhibitors are used for blood-pressure lowering. While you may not have elevated or high blood pressure, this drug will help lower the pressure running through your kidneys, in turn protecting them from further damage and helping repair the damage they have already sustained.
Kidney damage can also be caused by acute (short, severe) illness. For example, when my kidney disease came about, I had been in the hospital for several months with a very severe infection outside my lungs, resulting in 13 operations. It nearly killed me. The extra strain on all your organs, especially your kidneys, can cause them to over-exert themselves, increasing the likelihood of temporary damage. Your kidneys and your liver are your main filtration system for your entire body--they are breaking down all the medicines you take and the waste products your body creates. Typically, kidney disease caused by acute illness will be reversed on it's own with careful monitoring. If not, it can be cleared up through medications, regular testing, and careful monitoring.
For me, I did 24 hour kidney function tests once a month for 4 years (you just pee in a jug for a solid day and they record how much protein is in your urine). Then I went to every three months, then every 6 months, then once a year, and now only as needed. My kidney tests are nearly normal (still tiny amounts of protein). My blood pressure has always been normal and with careful control of my diabetes, I don't have to worry about further damaging my kidneys.
I wish you luck, Kristi! You are such a positive person. This experience will only make you stronger. Stay positive and keep us informed.