High blood sugar interferes with the glomerulus filtration rate. Inside the kidney there are thousands, hundreds of thousands of tubules through which all the blood in your body is directed, these glomerulus filter out toxins such as urea a by product of protein metabolism. They also maintain through feedback loops creatinine for example, which is a by product of muscle breakdown. Diabetes that is not well controlled causes muscle breakdown. Therefore a high reading of either the GFR and or creatinine indicate the beginning of kidney disease. However what you don't give are your HbA1c although your other tests fall within normal limits. Talk to your diabetic nurse, who should repeat those tests after 12 weeks. They could be an aberration or an indication of something else. But you would need another set of tests to confirm anything.